Using WebLogic jDriver for Oracle
Implementing with WebLogic jDriver for Oracle
Oracle client library versions, URLs, and Driver class names
Connecting using a DataSource object
Setting properties for WebLogic JDBC use
Inserting, updating, and deleting records
Creating and using stored procedures and functions
Disconnecting and closing objects
Working with ResultSets from stored procedures
WebLogic jDriver for Oracle and Oracle's NUMBER column
Using Oracle Long raw data types
Support for Oracle array fetches
Binding a parameter to an Oracle cursor
Notes on using CallableStatement
Notes on DatabaseMetaData methods
Writing Unicode data to a CLOB
Introduction
WebLogic jDriver for Oracle is a new name for the product previously known as jdbcKona/Oracle.
What's in this document
This document covers using the WebLogic jDriver for Oracle JDBC driver for the Oracle Database management system (DBMS). This driver is a Type-2 JDBC driver and requires the installation of Oracle client libraries on the machine accessing the Oracle Server.
This document also includes general notes and an implementation guide for using JDBC, and information on using Oracle-specific features with WebLogic jDriver for Oracle. The discussions and examples in this document assume that the reader is familiar with Java, general DBMS concepts, and Structured Query Language (SQL).
This document also covers recent updates to WebLogic jDriver for Oracle, as of version 5, that include new JDBC 2.0 for Oracle features such as Blob and Clob support and Batch updates.
If you are using WebLogic JDBC, BEA's multitier JDBC implementation, you should also refer to the Developers Guide Using WebLogic JDBC for more information.
Overview of BEA jDrivers
The BEA WebLogic jDrivers include a Type-2 native JDBC driver for Oracle and Type 4 JDBC drivers for Informix and Microsoft SQL Server. The Type-2 driver employs client libraries supplied by the database vendor while the Type-4 drivers are 100% pure Java; they connect to the database server at the wire level without vendor-supplied client libraries.
For more information, see WebLogic JDBC Options.
Software requirements
For details on the platforms, operating systems, JVMs, DBMS versions, and client libraries supported by the WebLogic jDrivers see Platform support for Weblogic jDrivers.
Installation
For installation instructions, see Installing WebLogic jDriver for Oracle.
Implementing with WebLogic jDriver for Oracle
This example follows a simple application through the basic steps:
The classes that you import into your application should include:
import java.sql.*;
import java.util.Properties; // required only if using a Properties
// object to set connection parameters
import weblogic.common.*;
The WebLogic jDriver for Oracle driver implements the java.sql interface. You write your application using the java.sql classes. You do not need to import the JDBC driver class; instead, you load the driver inside the application. This allows you to select an appropriate driver at runtime. You can even decide what DBMS to connect to after the program is compiled.
Setting CLASSPATH
When running a WebLogic jDriver for Oracle client using the driver provided with WebLogic Server you must put the following directory in your CLASSPATH:
weblogic/classes
(where weblogic is the directory containing your WebLogic Server installation)
If you are running a stand-alone version of WebLogic jDriver for Oracle, place the following directory in your classpath:
weblogic/oci/classes
(where weblogic is the directory containing your WebLogic jDriver for Oracle installation)
For more information on setting your CLASSPATH and other environment issues, see Setting your development environment
Oracle client library versions, URLs, and Driver class names
Depending on your platform, which version of the Oracle client libraries you are using, and whether or not you require access to JDBC 2.0 features (Blobs, Clobs, Batch updates), you need to use a different driver class name and URL.
You must also specify the correct driver version in your system's path. For more information, see Setting your path and client libraries.
JDBC 1.x
Driver class: weblogic.jdbc.oci.Driver
JDBC 2.0
Driver class: weblogic.jdbc20.oci.Driver
Connecting to an Oracle DBMS
These steps explain how to set up your application to connect to your Oracle DBMS using WebLogic jDriver for Oracle. In general, connecting happens in three steps:
Driver myDriver = (Driver)Class.forName
("weblogic.jdbc.oci.Driver").newInstance();
Properties props = new Properties();
props.put("user", "scott");
props.put("password", "secret");
props.put("server", "DEMO");
The server name ("DEMO" in the example above) refers to an entry in the tnsnames.ora file, which is located in your Oracle client installation and defines host names and other information about an Oracle database. If you do not supply a server name, the system will look for an environment variable (ORACLE_SID in the case of Oracle). You may also choose to add the server name to the URL, with this format:
"jdbc:weblogic:oracle:DEMO"
in which case you do not need to provide a "server" property.
You can also set properties in a single URL, for use with products like PowerSoft's PowerJ. For details, see Using URLs with WebLogic products.
Connection conn =
myDriver.connect("jdbc:weblogic:oracle", props);
In steps 1 and 3, you are describing the JDBC driver: in the first step, you use the full package name of the driver. Note that it is dot-delimited. In the third step, you identify the driver with its URL, which is colon-delimited. The URL must include at least weblogic:jdbc:mssqlserver4, and may include other information, including the server host name and the database name.
Note: The examples in this document use the driver name weblogic.jdbc.oci.Driver and the URL jdbc:weblogic:oracle. These are intended for use where JDBC 2.0 features are not required. You may also use the driver name weblogic.jdbc20.oci.Driver and the URL jdbc20:weblogic:oracle if you need to use JDBC 2.0 features. For more information on JDBC 2.0, see JDBC 2.0 for Oracle
There are additional restrictions regarding the use of JDBC 2.0. For more information, see Oracle client library versions, URLs, and Driver class names
Connection example
This example shows how to use a Properties object to connect to a database named "myDB."
Properties props = new Properties();
props.put("user", "scott");
props.put("password", "secret");
props.put("db", "myDB");
Driver myDriver = (Driver)
Class.forName("weblogic.jdbc.oci.Driver").newInstance();
Connection conn =
myDriver.connect("jdbc:weblogic:oracle", props);
Connecting using a DataSource object
If you are using WebLogic jDriver for Oracle as a middle-tier driver with WebLogic Server, you can also obtain a connection by using a DataSource object. For more information, see Using a DataSource object to get a connection.
Setting properties for WebLogic JDBC use
If you are using WebLogic JDBC in a multitier environment with the WebLogic jDriver for Oracle driver, you will set connection properties in a slightly different way. See Using WebLogic JDBC for more information.
About the Connection object
The Connection object is an important part of the application. The Connection class has constructors for many fundamental database objects that you will use throughout the application, and in the examples that follow, you will see the Connection object conn used frequently. Connecting to the database completes the initial portion of the application.
You should call the close() method on the Connection object as soon as you finish working with it, usually at the end of a class.
Setting Autocommit
The default transaction mode for JDBC assumes autocommit to be true. With WebLogic jDriver for Oracle, setting autocommit to false will improve performance.
Making a simple SQL query
The most fundamental task in database access is to retrieve data. With WebLogic jDriver for Oracle, this is a three-step process:
Statement stmt = conn.createStatement();
stmt.execute("select * from emp");
ResultSet rs = stmt.getResultSet();
while (rs.next()) {
System.out.println(rs.getString("empid") + " - " +
rs.getString("name") + " - " +
rs.getString("dept"));
}
ResultSetMetaData md = rs.getMetaData();
System.out.println("Number of columns: " +
md.getColumnCount());
for (int i = 1; i <= md.getColumnCount(); i++) {
System.out.println("Column Name: " +
md.getColumnName(i));
System.out.println("Nullable: " +
md.isNullable(i));
System.out.println("Precision: " +
md.getPrecision(i));
System.out.println("Scale: " +
md.getScale(i));
System.out.println("Size: " +
md.getColumnDisplaySize(i));
System.out.println("Column Type: " +
md.getColumnType(i));
System.out.println("Column Type Name: "+
md.getColumnTypeName(i));
System.out.println("");
}
stmt.close();
JDBC ResultSets have a basic functionality for dealing with data on the record level. You may find managing data easier with BEA's dbKona, which features a higher level of abstraction. dbKona's objects, like TableDataSet, QueryDataSet, and Record, as well as other features like automatic SQL generation and client-side results management, sit on top of JDBC. Check the Developers Guide Using dbKona, for more information.
Inserting, updating, and deleting records
We illustrate three common database tasks in this step: inserting, updating, and deleting records from a database table. We use a JDBC PreparedStatement for these operations; we create the PreparedStatement, then execute it and close it.
A PreparedStatement (subclassed from JDBC Statement) allows you to execute the same SQL over and over again with different values. PreparedStatements use the JDBC "?" syntax.
String inssql =
"insert into emp(empid, name, dept) values (?, ?, ?)";
PreparedStatement pstmt = conn.prepareStatement(inssql);
for (int i = 0; i < 100; i++) {
pstmt.setInt(1, i);
pstmt.setString(2, "Person " + i);
pstmt.setInt(3, i);
pstmt.execute():
}
pstmt.close();
We also use a PreparedStatement to update records. In this example, we add the value of the counter "i" to the current value of the "dept" field.
String updsql =
"update emp set dept = dept + ? where empid = ?";
PreparedStatement pstmt2 = conn.prepareStatement(updsql);
for (int i = 0; i < 100; i++) {
pstmt2.setInt(1, i);
pstmt2.setInt(2, i);
pstmt2.execute();
}
pstmt2.close();
Finally, we use a PreparedStatement to delete the records that added and then updated.
String delsql = "delete from emp where empid = ?";
PreparedStatement pstmt3 = conn.prepareStatement(delsql);
for (int i = 0; i < 100; i++) {
pstmt3.setInt(1, i);
pstmt3.execute();
}
pstmt3.close();
Creating and using stored procedures and functions
You can use WebLogic jDriver for Oracle to create, use, and drop stored procedures and functions. First, we execute a series of Statements to drop a set of stored procedures and functions from the database.
Statement stmt = conn.createStatement();
try {stmt.execute("drop procedure proc_squareInt");}
catch (SQLException e) {//code to handle the exception goes here;}
try {stmt.execute("drop procedure func_squareInt");}
catch (SQLException e) {//code to handle the exception goes here;}
try {stmt.execute("drop procedure proc_getresults");}
catch (SQLException e) {//code to handle the exception goes here;}
stmt.close();
We use a JDBC Statement to create a stored procedure or function, and then we use a JDBC CallableStatement (subclassed from Statement) with the JDBC "?" syntax to set IN and OUT parameters.
Note that Oracle does not natively support binding to "?" values in a SQL statement. Instead it uses ":1", ":2", etc. You can use either syntax in your SQL with WebLogic jDriver for Oracle.
Stored procedure input parameters are mapped to JDBC IN parameters, using the CallableStatement.setXXX() methods, like setInt(), and the JDBC PreparedStatement "?" syntax. Stored procedure output parameters are mapped to JDBC OUT parameters, using the CallableStatement.registerOutParameter() methods and JDBC PreparedStatement "?" syntax. A parameter may be both IN and OUT, which requires both a setXXX() and a registerOutParameter() call to be done on the same parameter number.
In this example, we use a JDBC Statement to create an Oracle stored procedure; then we execute the stored procedure with a CallableStatement. We use the registerOutParameter() method to set an output parameter for the squared value.
Statement stmt1 = conn.createStatement();
stmt1.execute
("CREATE OR REPLACE PROCEDURE proc_squareInt " +
"(field1 IN OUT INTEGER, field2 OUT INTEGER) IS " +
"BEGIN field2 := field1 * field1; field1 := " +
"field1 * field1; END proc_squareInt;");
stmt1.close();
// Native Oracle SQL is commented out here
// String sql = "BEGIN proc_squareInt(?, ?); END;";
// This is the correct syntax as specified by JDBC
String sql = "{call proc_squareInt(?, ?)}";
CallableStatement cstmt1 = conn.prepareCall(sql);
// Register out parameters
cstmt1.registerOutParameter(2, java.sql.Types.INTEGER);
for (int i = 0; i < 5; i++) {
cstmt1.setInt(1, i);
cstmt1.execute();
System.out.println(i + " " + cstmt1.getInt(1) + " "
+ cstmt1.getInt(2));
} cstmt1.close();
In the next example, we use similar code to create and execute a stored function that squares an integer.
Statement stmt2 = conn.createStatement();
stmt2.execute("CREATE OR REPLACE FUNCTION func_squareInt " +
"(field1 IN INTEGER) RETURN INTEGER IS " +
"BEGIN return field1 * field1; " +
"END func_squareInt;");
stmt2.close();
// Native Oracle SQL is commented out here
// sql = "BEGIN ? := func_squareInt(?); END;";
// This is the correct syntax specified by JDBC
sql = "{ ? = call func_squareInt(?)}";
CallableStatement cstmt2 = conn.prepareCall(sql);
cstmt2.registerOutParameter(1, Types.INTEGER);
for (int i = 0; i < 5; i++) {
cstmt2.setInt(2, i);
cstmt2.execute();
System.out.println(i + " " + cstmt2.getInt(1) +
" " + cstmt2.getInt(2));
}
cstmt2.close();
This next example uses a stored procedure named sp_getmessages (the code for this stored procedure is not included with this example) This stored procedure takes a message number as an input parameter, looks up the message number in a table containing the message text and returns the message text in a ResultSet as an output parameter. Note that you must process all ResultSets returned by a stored procedure using the Statement.execute() and Statement.getResult() methods before OUT parameters and return status are available.
First, we set up the three parameters to the CallableStatement:
String sql = "{ ? = call sp_getmessage(?, ?)}";
CallableStatement stmt = conn.prepareCall(sql);
stmt.registerOutParameter(1, java.sql.Types.INTEGER);
stmt.setInt(2, 18000); // msgno 18000
stmt.registerOutParameter(3, java.sql.Types.VARCHAR);
We execute the stored procedure and check the return value to see if the ResultSet is empty. If it is not, we use a loop to retrieve and display its contents.
boolean hasResultSet = stmt.execute();
while (true)
{
ResultSet rs = stmt.getResultSet();
int updateCount = stmt.getUpdateCount();
if (rs == null && updateCount == -1) // no more results
break;
if (rs != null) {
// Process the ResultSet until it is empty
while (rs.next()) {
System.out.println
("Get first col by id:" + rs.getString(1));
}
} else {
// we have an update count
System.out.println("Update count = " +
stmt.getUpdateCount());
}
stmt.getMoreResults();
}
Once we finish processing the ResultSet, the OUT parameters and return status are available.
int retstat = stmt.getInt(1);
String msg = stmt.getString(3);
System.out.println("sp_getmessage: status = " +
retstat + " msg = " + msg);
stmt.close();
Disconnecting and closing objects
There are occasions on which you will want to call the commit() method to commit changes you've made to the database before you close the connection.
When autocommit is set to true (the default JDBC transaction mode) each SQL statement is its own transaction. After we created the Connection for these examples, however, we set autocommit to false; in this mode, the Connection always has an implicit transaction associated with it, and any call to the rollback() or commit() methods will end the current transaction and start a new one. Calling commit() before close() ensures that all of the transactions are completed before closing the Connection.
Just as you close Statements, PreparedStatements, and CallableStatements when you have finished working with them, you should always call the close() method on the connection as final cleanup in your application, in a try {} block, and you should catch exceptions and deal with them appropriately. The final two lines of this example include a call to commit and then a call to close the connection.
conn.commit();
conn.close();
Code example
Here are selected portions of the code used in these examples to give you an overall idea of structure for a JDBC application. The code example shown here includes retrieving data, displaying metadata, inserting, deleting, and updating data, and stored procedures and functions. Note the explicit calls to close() for each JDBC-related object, and note also that we close the Connection itself in a finally {} block, with the call to close() wrapped in a try {} block.
package examples.jdbc.oracle;
import java.sql.*;
import java.util.Properties;
import weblogic.common.*;
public class test {
static int i;
Statement stmt = null;
public static void main(String[] argv) {
try {
Properties props = new Properties();
props.put("user", "scott");
props.put("password", "tiger");
props.put("server", "DEMO");
Driver myDriver = (Driver) Class.forName
("weblogic.jdbc.oci.Driver").newInstance();
Connection conn =
myDriver.connect("jdbc:weblogic:oracle", props);
}
catch (Exception e)
e.printStackTrace();
}
try {
// This will improve performance in Oracle
// You'll need an explicit commit() call later
conn.setAutoCommit(false);
stmt = conn.createStatement();
stmt.execute("select * from emp");
ResultSet rs = stmt.getResultSet();
while (rs.next()) {
System.out.println(rs.getString("empid") + " - " +
rs.getString("name") + " - " +
rs.getString("dept"));
}
ResultSetMetaData md = rs.getMetaData();
System.out.println("Number of Columns: " +
md.getColumnCount());
for (i = 1; i <= md.getColumnCount(); i++) {
System.out.println("Column Name: " +
md.getColumnName(i));
System.out.println("Nullable: " +
md.isNullable(i));
System.out.println("Precision: " +
md.getPrecision(i));
System.out.println("Scale: " +
md.getScale(i));
System.out.println("Size: " +
md.getColumnDisplaySize(i));
System.out.println("Column Type: " +
md.getColumnType(i));
System.out.println("Column Type Name: "+
md.getColumnTypeName(i));
System.out.println("");
}
rs.close();
stmt.close();
Statement stmtdrop = conn.createStatement();
try {stmtdrop.execute("drop procedure proc_squareInt");}
catch (SQLException e) {;}
try {stmtdrop.execute("drop procedure func_squareInt"); }
catch (SQLException e) {;}
try {stmtdrop.execute("drop procedure proc_getresults"); }
catch (SQLException e) {;}
stmtdrop.close();
// Create a stored procedure
Statement stmt1 = conn.createStatement();
stmt1.execute
("CREATE OR REPLACE PROCEDURE proc_squareInt " +
"(field1 IN OUT INTEGER, " +
"field2 OUT INTEGER) IS " +
"BEGIN field2 := field1 * field1; " +
"field1 := field1 * field1; " +
"END proc_squareInt;");
stmt1.close();
CallableStatement cstmt1 =
conn.prepareCall("BEGIN proc_squareInt(?, ?); END;");
cstmt1.registerOutParameter(2, Types.INTEGER);
for (i = 0; i < 100; i++) {
cstmt1.setInt(1, i);
cstmt1.execute();
System.out.println(i + " " + cstmt1.getInt(1) +
" " + cstmt1.getInt(2));
}
cstmt1.close();
// Create a stored function
Statement stmt2 = conn.createStatement();
stmt2.execute
("CREATE OR REPLACE FUNCTION func_squareInt " +
"(field1 IN INTEGER) RETURN INTEGER IS " +
"BEGIN return field1 * field1; END func_squareInt;");
stmt2.close();
CallableStatement cstmt2 =
conn.prepareCall("BEGIN ? := func_squareInt(?); END;");
cstmt2.registerOutParameter(1, Types.INTEGER);
for (i = 0; i < 100; i++) {
cstmt2.setInt(2, i);
cstmt2.execute();
System.out.println(i + " " + cstmt2.getInt(1) +
" " + cstmt2.getInt(2));
}
cstmt2.close();
// Insert 100 records
System.out.println("Inserting 100 records...");
String inssql =
"insert into emp(empid, name, dept) values (?, ?, ?)";
PreparedStatement pstmt = conn.prepareStatement(inssql);
for (i = 0; i < 100; i++) {
pstmt.setInt(1, i);
pstmt.setString(2, "Person " + i);
pstmt.setInt(3, i);
pstmt.execute();
}
pstmt.close();
// Update 100 records
System.out.println("Updating 100 records...");
String updsql =
"update emp set dept = dept + ? where empid = ?";
PreparedStatement pstmt2 = conn.prepareStatement(updsql);
for (i = 0; i < 100; i++) {
pstmt2.setInt(1, i);
pstmt2.setInt(2, i);
pstmt2.execute();
}
pstmt2.close();
// Delete 100 records
System.out.println("Deleting 100 records...");
String delsql = "delete from emp where empid = ?";
PreparedStatement pstmt3 = conn.prepareStatement(delsql);
for (i = 0; i < 100; i++) {
pstmt3.setInt(1, i);
pstmt3.execute();
}
pstmt3.close();
conn.commit();
}
catch (Exception e) {
// Deal with failures appropriately
}
finally {
try {conn.close();}
catch (Exception e) {
// Catch and deal with exception
}
}
}
}
Working with ResultSets from stored procedures
Executing stored procedures may return multiple ResultSets. When you process ResultSets returned by a stored procedure, using Statement.execute() and Statement.getResultSet() methods, you must process all ResultSets returned before any of the OUT parameters or the return status codes are available.
Support for JDBC Extended SQL
The JavaSoft JDBC specification includes SQL Extensions, also called SQL Escape Syntax. All WebLogic jDrivers support Extended SQL. Extended SQL provides access to common SQL extensions in a way that is portable between DBMSs.
For example, the function to extract the day name from a date is not defined by the SQL standards. For Oracle, the SQL is:
select to_char(date_column, 'DAY') from table_with_dates
The equivalent function for Sybase and Microsoft SQL Server is:
select datename(dw, date_column) from table_with_dates
Using Extended SQL, you can retrieve the day name for both DBMSs as follows:
select {fn dayname(date_column)} from table_with_dates
Here's an example that demonstrates several features of Extended SQL:
String query =
"-- This SQL includes comments and " +
"JDBC extended SQL syntax.\n" +
"select into date_table values( \n" +
" {fn now()}, -- current time \n" +
" {d '1997-05-24'}, -- a date \n" +
" {t '10:30:29' }, -- a time \n" +
" {ts '1997-05-24 10:30:29.123'}, -- a timestamp\n" +
" '{string data with { or } will not be altered}'\n" +
"-- Also note that you can safely include" +
" { and } in comments or\n" +
"-- string data.";
Statement stmt = conn.createStatement();
stmt.executeUpdate(query);
Extended SQL is delimited with curly braces ("{}") to differentiate it from common SQL. Comments are preceded by two hyphens, and are ended by a new line ("\n"). The entire Extended SQL sequence, including comments, SQL, and Extended SQL, is placed within double quotes and passed to the execute() method of a Statement object. Here is Extended SQL used as part of a CallableStatement:
CallableStatement cstmt =
conn.prepareCall("{ ? = call func_squareInt(?)}");
This example shows that you can nest extended SQL expressions:
select {fn dayname({fn now()})}
You can retrieve lists of supported Extended SQL functions from a DatabaseMetaData object. This example shows how to list all the functions a JDBC driver supports:
DatabaseMetaData md = conn.getMetaData();
System.out.println("Numeric functions: " +
md.getNumericFunctions());
System.out.println("\nString functions: " +
md.getStringFunctions());
System.out.println("\nTime/date functions: " +
md.getTimeDateFunctions());
System.out.println("\nSystem functions: " +
md.getSystemFunctions());
conn.close();
Refer to chapter 11 of the JDBC 1.2 specification at JavaSoft for a description of Extended SQL.
Additional Oracle features
Allowing mixed case metadata
WebLogic jDriver for Oracle also allows setting the property allowMixedCaseMetaData. When set to the boolean true, this property sets up the Connection to use mixed case in calls to DatabaseMetaData methods. If this property is set to false, Oracle defaults to UPPERCASE for database metadata. Here is an example of setting up the properties to include this feature:
Properties props = new Properties();
props.put("user", "scott");
props.put("password", "tiger");
props.put("server", "DEMO");
props.put("allowMixedCaseMetaData", "true");
Driver myDriver = (Driver)
Class.for.Name(weblogic.jdbc.oci.Driver).newInstance();
Connection conn =
myDriver.connect("jdbc:weblogic:oracle", props);
If you do not set this property, WebLogic jDriver for Oracle defaults to the Oracle default, which uses UPPERCASE for database metadata.
The table below shows the recommended mapping between Oracle data types and Java types. There are additional possibilities for representing Oracle data types in Java. Calling the getObject() method when processing result sets will return the default Java data type for the Oracle column being queried.
Figure 2-1 Mapping of types between Oracle and WebLogic jDriver for Oracle.
Oracle |
WebLogic jDriver for Oracle |
Varchar |
String |
Number |
Tinyint |
Number |
Smallint |
Number |
Integer |
Number |
Long |
Number |
Float |
Number |
Numeric |
Number |
Double |
Long |
Longvarchar |
RowID |
String |
Date |
Timestamp |
Raw |
(var)Binary |
Long raw |
Longvarbinary |
Char |
(var)Char |
Boolean* |
Number OR Varchar |
MLS label |
String |
Blob |
Blob |
Clob |
Clob |
*Note that when PreparedStatement.setBoolean() is called, it will convert a VARCHAR type to "1" or "0" (string), and it will convert a NUMBER type to 1 or 0 (number).
WebLogic jDriver for Oracle and Oracle's NUMBER column
Oracle provides a column type called NUMBER, which can be optionally specified with a precision and a scale, in the forms NUMBER(P) and NUMBER(P,S). Even in the simple unqualified NUMBER form, this column can hold all number types from small integer values to very large floating point numbers, with high precision.
WebLogic jDriver for Oracle reliably converts the values in a column to the Java type requested when a WebLogic jDriver for Oracle application asks for a value from such a column. Of course, if a value of 123.456 is asked for with getInt(), the value will be rounded.
The method getObject(), however, poses a little more complexity. WebLogic jDriver for Oracle guarantees to return a Java object which will represent any value in a NUMBER column with no loss in precision. This means that a value of 1 can be returned in an Integer, but a value like 123434567890.123456789 can only be returned in a BigDecimal.
There is no metadata from Oracle to report the maximum precision of the values in the column, so WebLogic jDriver for Oracle must decide what sort of object to return based on each value. This means that one ResultSet may return multiple Java types from getObject() for a given NUMBER column. A table full of integer values may all be returned as Integer from getObject(), whereas a table of floating point measurements may be returned primarily as Double, with some Integer if any value happens to be something like "123.00". Oracle does not provide any information to distinguish between a NUMBER value of "1" and a NUMBER of "1.0000000000".
There is some more reliable behavior with qualified NUMBER columns, that is, those defined with a specific precision. Oracle's metadata provides these parameters to the driver so WebLogic jDriver for Oracle will always return a Java object appropriate for the given precision and scale, regardless of the values in the table.
Column definition |
Returned by getObject() |
NUMBER(P <= 9) |
Integer |
NUMBER(P <= 18) |
Long |
NUMBER(P = 19) |
BigDecimal |
NUMBER(P <=16, S 0) |
Double |
NUMBER(P = 17, S 0) |
BigDecimal |
Using Oracle Long raw data types
There are two properties available for use with WebLogic jDriver for Oracle in support of Oracle's chunking of Blobs, Clobs, Long, and Long raw data types. Although Blob and Clob data types are only supported with Oracle Version 8 and JDBC 2.0, these properties also apply to Oracle's Long raw datatype, which is available in Oracle Version 7 and JDBC 1.x. For more information on theses properties, see Connection properties in the JDBC 2.0 section
Waiting on Oracle resources
Note: The waitOnResources() method is not supported when using the Oracle 8 API. (For more information on your Oracle client, server, and API versions, see Setting your path and client libraries.)
The WebLogic jDriver for Oracle driver supports Oracle's oopt() C functionality, which allows a client to wait until resources become available. The Oracle C function sets options in cases where requested resources are not available; for example, whether to wait for locks.
The developer can set whether a client will wait for DBMS resources, or will receive an immediate exception. Here's an example from the example examples/jdbc/oracle/waiton.java:
java.util.Properties props = new java.util.Properties();
props.put("user", "scott");
props.put("password", "tiger");
props.put("server", "myserver");
Driver myDriver = (Driver)
Class.forName("weblogic.jdbc.oci.Driver").newInstance();
// You must cast the Connection as a weblogic.jdbc.oci.Connection
// to take advantage of this extension
Connection conn =(weblogic.jdbc.oci.Connection)
myDriver.connect("jdbc:weblogic:oracle", props);
// After constructing the Connection object, immediately call
// the waitOnResources method
conn.waitOnResources(true);
Note that use of this method can cause several error return codes while waiting for internal resources that are locked for short durations.
To take advantage of this feature, you must first cast your Connection object as a weblogic.jdbc.oci.Connection, and then call the waitOnResources() method.
This functionality is described in section 4-97 of The OCI Functions for C.
Autocommit
The default transaction mode for JDBC WebLogic jDriver for Oracle assumes autocommit to be true. You will improve the performance of your programs by setting autocommit to false after creating a Connection object with the statement:
Connection.setAutoCommit(false);
Transaction isolation levels
WebLogic jDriver for Oracle supports the following transaction isolation levels:
The Oracle DBMS only supports these two isolation levels. Unlike other JDBC drivers, WebLogic jDriver for Oracle throws an exception if you try to use an isolation level that is unsupported. Some drivers silently ignore attempts to set an unsupported isolation level.
The READ_UNCOMMITTED transaction isolation level is not supported.
JDBC and your WebLogic jDriver for Oracle driver handle character strings in Java as Unicode strings. Since the Oracle DBMS uses a different codeset, the driver must convert character strings from Unicode to the codeset used by Oracle. The WebLogic jDriver for Oracle will examine the value stored in the Oracle environment variable NLS_LANG and select a codeset for the JDK to use for the conversion, using the mapping shown in the table below. If the NLS_LANG variable is not set, or is set to a codeset not recognized by the JDK, the driver will not be able to determine the correct codeset. (Consult your Oracle documentation for information on the correct syntax for setting NLS_LANG.)
If you are converting codesets, you should pass the following property to the WebLogic jDriver for Oracle with the Driver.connect() method when you establish the connection in your code:
props.put("weblogic.oci.min_bind_size", 660);
This property defines the minimum size of buffers to be bound. The default is 2000 bytes, which is also the maximum value. If you are converting codesets, you should use this property to reduce the bind size to a maximum of 660, one-third of the maximum 2000 bytes, since Oracle codeset conversion triples the buffer to allow for expansion.
WebLogic jDriver for Oracle provides a way to set the codeset from within your Java code. By setting a connection property, weblogic.codeset, you can override the value stored in the NLS_LANG environment variable. For example, to use the cp932 codeset, create a Properties object and set the weblogic.codeset property before calling Driver.connect(), as in this example:
java.util.Properties props = new java.util.Properties();
props.put("weblogic.codeset", "cp932");
props.put("user", "scott");
props.put("password", "tiger");
String connectUrl = "jdbc:weblogic:oracle";
Driver myDriver = (Driver)
Class.forName("weblogic.jdbc.oci.Driver").newInstance();
Connection conn =
myDriver.connect(connectUrl, props);
Note that codeset support can vary with different JVMs. Check the documentation for the JDK you are using to determine if a particular codeset is supported. You can find the List of supported encodings for JDK 1.1 at the JavaSoft website.
Table 2-1 Mapping of NLS_LANG settings to JDK codesets
NLS_LANG |
JDK codeset |
us7ascii |
ASCII |
ja16sjis |
SJIS |
us8pc437 |
Cp437 |
we8ebcdic37 |
Cp1046 |
we8ebcdic500 |
Cp500 |
we8pc850 |
Cp850 |
we8iso8859p1 |
ISO8859_1 |
ee8iso8859p2 |
ISO8859_2 |
se8iso8859p3 |
ISO8859_3 |
nee8iso8859p4 |
ISO8859_4 |
cl8iso8859p5 |
ISO8859_5 |
ar8iso8859p6 |
ISO8859_6 |
el8iso8859p7 |
ISO8859_7 |
iw8iso8859p8 |
ISO8859_8 |
we8iso8859p9 |
ISO8859_9 |
ne8iso8859p10 |
ISO8859_10 |
ru8pc866 |
Cp866 |
ee8pc852 |
Cp852 |
ru8pc855 |
Cp855 |
tr8pc857 |
Cp857 |
cl8maccyrillic |
MacCyrillic |
we8pc860 |
Cp860 |
is8pc861 |
Cp861 |
ee8mswin1250 |
Cp1250 |
cl8mswin1251 |
Cp1251 |
el8mswin1253 |
Cp1253 |
n8pc865 |
Cp865 |
ee8macce |
MacCentralEurope |
ee8maccroatian |
MacCroatian |
tr8macturkish |
MacTurkish |
is8macicelandic |
MacIceland |
el8macgreek |
MacGreek |
we8macroman8 |
MacRoman |
th8macthai |
MacThai |
el8pc737 |
Cp737 |
lt8pc772 |
Cp772 |
lt8pc774 |
Cp774 |
cdn8pc863 |
Cp863 |
ja16euc |
EUC_JP |
ko16ksc5601 |
EUC_KR |
zht16big5 |
Big5 |
al24utffss |
UTF8 |
utf8 |
UTF8 |
WebLogic jDriver for Oracle supports Oracle array fetches. Calling ResultSet.next() the first time will get an array of rows and store it in memory, rather than retrieving a single row. Each subsequent call to next() will read a row from the rows in memory until they are exhausted, and only then will next() go back to the database.
You set a property (java.util.Property) to control the size of the array fetch. The property is weblogic.oci.cacheRows; it is set by default to 100. Here's an example of setting this property to 300, which means that calls to next() only hit the database once for each 300 rows retrieved by the client.
Properties props = new Properties();
props.put("user", "scott");
props.put("password", "tiger");
props.put("server", "DEMO");
props.put("weblogic.oci.cacheRows", "300");
Driver myDriver = (Driver)
Class.forName("weblogic.jdbc.oci.Driver").newInstance();
Connection conn = myDriver.connect("jdbc:weblogic:oracle", props);
You can improve client performance and lower the load on the database server by taking advantage of this JDBC extension. Caching rows in the client, however, requires client resources. You should tune your application for the best balance between performance and client resources, depending upon your network configuration and your application.
If any columns in a SELECT are of type LONG, the cache size will be temporarily reset to one (1) for the ResultSet associated with that select statement.
Using stored procedures
Binding a parameter to an Oracle cursor
WebLogic has created an extension to JDBC (weblogic.jdbc.oci.CallableStatement) that allows you to bind a parameter for a stored procedure to an Oracle cursor. You can create a JDBC ResultSet object with the results of the stored procedure. This allows you to return multiple ResultSets in an organized way. The ResultSets are determined at run time in the stored procedure.
Here is an example. First define the stored procedures as follows:
create or replace package
curs_types as
type EmpCurType is REF CURSOR RETURN emp%ROWTYPE;
end curs_types;
/
create or replace procedure
single_cursor(curs1 IN OUT curs_types.EmpCurType,
ctype in number) AS BEGIN
if ctype = 1 then
OPEN curs1 FOR SELECT * FROM emp;
elsif ctype = 2 then
OPEN curs1 FOR SELECT * FROM emp where sal 2000;
elsif ctype = 3 then
OPEN curs1 FOR SELECT * FROM emp where deptno = 20;
end if;
END single_cursor;
/
create or replace procedure
multi_cursor(curs1 IN OUT curs_types.EmpCurType,
curs2 IN OUT curs_types.EmpCurType,
curs3 IN OUT curs_types.EmpCurType) AS
BEGIN
OPEN curs1 FOR SELECT * FROM emp;
OPEN curs2 FOR SELECT * FROM emp where sal 2000;
OPEN curs3 FOR SELECT * FROM emp where deptno = 20;
END multi_cursor;
/
In your Java code, you'll construct CallableStatements with the stored procedures and register the output parameter as data type java.sql.Types.OTHER. When you retrieve the data into a ResultSet, use the output parameter index as an argument for the getResultSet() method.
weblogic.jdbc.oci.CallableStatement cstmt =
(weblogic.jdbc.oci.CallableStatement)conn.prepareCall(
"BEGIN OPEN ? " +
"FOR select * from emp; END;");
cstmt.registerOutParameter(1, java.sql.Types.OTHER);
cstmt.execute();
ResultSet rs = cstmt.getResultSet(1);
printResultSet(rs);
rs.close();
cstmt.close();
weblogic.jdbc.oci.CallableStatement cstmt2 =
(weblogic.jdbc.oci.CallableStatement)conn.prepareCall(
"BEGIN single_cursor(?, ?); END;");
cstmt2.registerOutParameter(1, java.sql.Types.OTHER);
cstmt2.setInt(2, 1);
cstmt2.execute();
rs = cstmt2.getResultSet(1);
printResultSet(rs);
cstmt2.setInt(2, 2);
cstmt2.execute();
rs = cstmt2.getResultSet(1);}
printResultSet(rs);
cstmt2.setInt(2, 3);
cstmt2.execute();
rs = cstmt2.getResultSet(1);
printResultSet(rs);
cstmt2.close();
weblogic.jdbc.oci.CallableStatement cstmt3 =
(weblogic.jdbc.oci.CallableStatement)conn.prepareCall(
"BEGIN multi_cursor(?, ?, ?); END;");
cstmt3.registerOutParameter(1, java.sql.Types.OTHER);
cstmt3.registerOutParameter(2, java.sql.Types.OTHER);
cstmt3.registerOutParameter(3, java.sql.Types.OTHER);
cstmt3.execute();
ResultSet rs1 = cstmt3.getResultSet(1);
ResultSet rs2 = cstmt3.getResultSet(2);
ResultSet rs3 = cstmt3.getResultSet(3);
For the full code for this example, including the printResultSet() method, see the examples in the examples/jdbc/oracle/ directory.
Note that the default size of an Oracle stored procedure string is 256K.
Notes on using CallableStatement
The default length of a string bound to an OUTPUT parameter of a CallableStatement is 128 characters. If the value you assign to the bound parameter exceeds that length, you'll get the following error:
ORA-6502: value or numeric error
You can adjust the length of the value of the bound parameter by passing an explicit length with the scale argument to the CallableStatement.registerOutputParameter() method. Here is a code example that binds a VARCHAR that will never be larger than 256 characters:
CallableStatement cstmt =
conn.prepareCall("BEGIN testproc(?); END;");
cstmt.registerOutputParameter(1, Types.VARCHAR, 256);
cstmt.execute();
System.out.println(cstmt.getString());
cstmt.close();
Notes on DatabaseMetaData methods
There are some variations in the implementation of DatabaseMetaData methods that are specific to Oracle and are detailed here:
The JDBC 2.0 specification defines new functionality that was not available in earlier versions of JDBC, some of which is not yet supported by current DBMS products and therefore has not been implemented in this driver.
New JDBC 2.0 features implemented in this driver:
WebLogic jDriver for Oracle can now handle this Oracle data type.
WebLogic jDriver for Oracle can now handle this Oracle data type.
A better way to handle characters streams-as streams of characters, not byte arrays.
You can now send multiple statements to the database as a single unit.
The above features are available in addition to all of the existing JDBC functionality previously available in the WebLogic jDriver for Oracle. All of your existing code for previous drivers will work with this new driver. .
Configuration
Since JDBC 2.0 is a Java 2 specification, you must run WebLogic jDriver for Oracle in a Java 2 environment. This means using one of the BEA supported Java Virtual Machines, such as JDK 1.2.x to run your JDBC clients. For a complete list of supported configurations, see the WebLogic Platform support page.
If you will be using JDBC 2.0 features of WebLogic jDriver for Oracle in a multitier environment with the WebLogic RMI, T3, JTS, or pool drivers, then you must run your WebLogic Server in a JDK 1.2.x JVM.
Driver class
The class name for the WebLogic jDriver for Oracle JDBC 2.0 driver is:
weblogic.jdbc20.oci.Driver
Driver URL
The URL for the WebLogic jDriver for Oracle JDBC 2.0 driver is:
jdbc20:weblogic:oracle
Overview of BLOBs and CLOBs
The BLOB (Binary Large Object) and CLOB (Character Large Object) data types were made available with the release of Oracle version 8. The JDBC 2.0 specification and WebLogic jDriver for Oracle also support these data types. This section contains information on using these data types.
Transaction boundaries
BLOBs or CLOBs in Oracle behave differently than other data types in regards to transactional boundaries (statements issued before a SQL commit or rollback statement). in that a BLOB or CLOB will be come inactive as soon as a transaction is committed. If AutoCommit is set to TRUE, the transaction will be automatically committed after each command issued on the connection, including SELECT statements. For this reason you will need to set AutoCommit to false if you need to have a BLOB or CLOB available across multiple SQL statements. You will then need to manually commit (or rollback) the transactions at the appropriate time. To set AutoCommit to false, issue the following command:
conn.setAutoCommit(false); // where conn is your connection object
The BLOB data type, available with Oracle version 8, allows you to store and retrieve large binary objects in an Oracle table. Although BLOBs are defined as part of the JDBC 2.0 specification, the specification does not provide methods to update BLOB columns in a table. The BEA WebLogic implementation of BLOBs, however, does provide this functionality by means of an extension to JDBC 2.0.
Connection properties
Import statements
To use the BLOB functionality described in this section, import the following classes in your client code:
import java.sql.*;
import java.util.*;
import java.io.*;
import weblogic.jdbc20.common.*;
Initializing a BLOB field
When you first insert a row containing a BLOB data type, you must insert the row with an "empty" BLOB before the field can be updated with real data. You can insert an empty BLOB with the Oracle EMPTY_BLOB() function.
stmt.execute("INSERT into myTable values (1,EMPTY_BLOB()");
java.sql.Blob myBlob = null;
Statement stmt2 = conn.createStatement();
stmt2.execute("SELECT myBlobColumn from myTable");
ResultSet rs = stmt2.getResultSet();
rs.next() {
myBlob = rs.getBlob("myBlobColumn");
// do something with the BLOB
}
Writing binary data to a BLOB
To write binary data to a BLOB column:
java.io.InputStream is = // create your input stream
java.io.OutputStream os =
((weblogic.jdbc20.common.OracleBlob) myBlob).getBinaryOutputStream();
byte[] inBytes = new byte[65534]; // see note below
int numBytes = is.read(inBytes);
while (numBytes > 0) {
os.write(inBytes, 0, numBytes);
numBytes = is.read(inBytes);
}
os.flush();
Note: The value [65534] in the above code presumes that you have not set the weblogic.oci.select.BlobChunkSize property whose default is 65534. If you have set this property, setting the byte[] value to match the value set in the weblogic.oci.select.BlobChunkSize property will provide the most efficient handling of the data. For more information on this property, see Connection properties.
os.close();
pstmt.close();
conn.close();
Writing a BLOB object
Writing a BLOB object to a table is performed with Prepared Statements. For example, to write the myBlob object to the table myOtherTable:
PreparedStatement pstmt = conn.preparedStatement(
"UPDATE myOtherTable SET myOtherBlobColumn = ? WHERE id = 12");
pstmt.setBlob(1, myBlob);
Reading BLOB data
When you retrieve a BLOB column with the getBlob() method and then use a ResultSet from a SQL SELECT statement, only a pointer to the BLOB data is returned; the binary data is not actually transferred to the client until the getBinaryStream() method is called and the data is read into the stream object.
To read BLOB data from an Oracle table:
stmt2.execute("SELECT myBlobColumn from myTable");
int STREAM_SIZE = 10;
byte[] r = new byte[STREAM_SIZE];
ResultSet rs = stmt2.getResultSet();
java.sql.Blob myBlob = null;
while (rs.next) {
myBlob = rs.getBlob("myBlobColumn");
java.io.InputStream readis = myBlob.getBinaryStream();
for (int i=0 ; i < STREAM_SIZE ; i++) {
r[i] = (byte) readis.read();
System.out.println("output [" + i + "] = " + r[i]);
}
rs.close();
stmt2.close();
Note: You can also use a CallableStatement to generate a ResultSet. This ResultSet can then be used as shown above. See your JDK documentation under java.sql.CallableStatment for details.
Other methods
The following methods of the java.sql.Blob interface are also implemented in the WebLogic jDriver for Oracle JDBC 2.0 driver. For details, see your JDK documentation:
The position() method is not implemented.
CLOBs
The CLOB data type, available with Oracle version 8, enables storage of large character strings in an Oracle table. Since the JDBC 2.0 specification does not include functionality to directly update CLOB columns, BEA has implemented the methods getAsciiOutputStream() (for ASCII data) and getCharacterOutputStream() (for Unicode data) to insert or update a CLOB.
Codeset support
Depending on which version of the Oracle Server and client you are using you may need to set one of the following properties by passing them to the Connection object when you establish your connection the DBMS in your Java client code.
Initializing a CLOB field
When you first insert a row containing a CLOB data type, you must insert the row with an "empty" CLOB before the field can be updated with real data. You can insert an empty CLOB with the Oracle EMPTY_CLOB() function.
stmt.execute("INSERT into myTable VALUES (1,EMPTY_CLOB()");
java.sql.Clob myClob = null;
Statement stmt2 = conn.createStatement();
stmt2.execute("SELECT myClobColumn from myTable");
ResultSet rs = stmt2.getResultSet();
while (rs.next) {
myClob = rs.getClob("myClobColumn");
}
Writing ASCII data to a CLOB
To write ASCII character data to a CLOB column:
String s = // some ASCII data
java.io.OutputStream os =
((weblogic.jdbc20.common.OracleClob) myclob).getAsciiOutputStream();
byte[] b = s.getBytes("ASCII");
os.write(b);
os.flush();
os.close();
pstmt.close();
conn.close();
Writing Unicode data to a CLOB
To write Unicode character data to a CLOB column:
String s = // some Unicode character data
java.io.Writer wr =
((weblogic.jdbc20.common.OracleClob) myclob).getCharacterOutputStream();
char[] b = s.toCharArray(); // converts 's' to a character array
wr.write(b);
wr.flush();
wr.close();
pstmt.close();
conn.close();
Writing CLOB objects
Writing a CLOB object to a table is performed with Prepared Statements. For example, to write the myClob object to the table myOtherTable:
PreparedStatement pstmt = conn.preparedStatement(
"UPDATE myOtherTable SET myOtherClobColumn = ? WHERE id = 12");
pstmt.setClob(1, myClob);
Reading CLOB data
When a CLOB column is retrieved using a result set from a SQL SELECT statement, only a pointer to the CLOB data is returned; the actual data is not transferred to the client with the result set until the getAsciiStream() method is called and the characters are read in to the stream.
To read CLOB data from an Oracle table:
java.sql.Clob myClob = null;
Statement stmt2 = conn.createStatement();
stmt2.execute("SELECT myClobColumn from myTable");
ResultSet rs = stmt2.getResultSet();
while (rs.next) {
myClob = rs.getClob("myClobColumn");
java.io.InputStream readClobis =
myReadClob.getAsciiStream();
char[] c = new char[26];
for (int i=0 ; i < 26 ; i++) {
c[i] = (char) readClobis.read();
System.out.println("output [" + i + "] = " + c[i]);
}
}
rs.close();
stmt2.close();
Note: You can also use a CallableStatement to generate a ResultSet. This ResultSet can then be used as shown above. See your JDK documentation under java.sql.CallableStatment for details.
Other methods
The following methods of the java.sql.Clob interface are also implemented in the WebLogic jDriver for Oracle JDBC 2.0 driver. For details, see your JDK documentation:
The position() method is not implemented.
Character and ASCII Streams
Some new methods are included in the JDBC 2.0 specification that allow character and ASCII streams to be manipulated as characters rather than as bytes, as was implemented in earlier versions. The following methods for handling character and ASCII streams are implemented in WebLogic jDriver for Oracle.
Unicode character Streams
ASCII character streams
For details on using these methods, consult your JDK documentation.
Batch updates
Batch updates are a new feature of JDBC 2.0 that allows you to send multiple SQL update statements to the DBMS as a single unit. Depending on the application, this can provide improved performance over sending multiple update statements individually. The Batch update feature is available in the Statement interface and requires the use of SQL statements that return an update count and do not return a result set. Using Batch updates with the callableStatement or preparedStatement is not supported.
The following SQL statements can be used with Batch updates:
This is the basic procedure for using Batch updates:
Statement stmt = conn.createStatement();
stmt.addBatch("INSERT INTO batchTest VALUES ('JOE', 20,35)");
stmt.addBatch("INSERT INTO batchTest VALUES ('Bob', 30,44)");
stmt.addBatch("INSERT INTO batchTest VALUES ('Ed', 34,22)");
stmt.executeBatch();
If any of the statements fail an exception will be thrown, and none of the statements will be executed.
Clearing the batch
You may clear a batch of statements that was created using addBatch() method with the clearBatch() method. For example:
stmt.clearBatch();
Update counts
According to the JDBC 2.0 specification, the executeBatch() method should return an array of Integers containing the number of rows updated for each Statement. The Oracle DBMS, however, does not supply this information to the driver. The Oracle DBMS will instead return -2 for all updates.
Using with JDBC 1
If you are running your client application (or WebLogic Server, if WebLogic jDriver for Oracle is being used in the middle tier) under JDK 1.1, you may use Batch updates by casting your Statement object to weblogic.jdbc.oci.Statement. For example:
weblogic.jdbc.oci.Statement stmt =
(weblogic.jdbc.oci.Statement) conn.createStatement();
New date methods
The following methods have a new signature which takes a java.util.Calendar object as a parameter. java.util.Calendar allows you to specify time zone and location information that is used to translate dates. Consult your JDK API guide for details on using the java.util.Calendar class.
java.sql.PreparedStatement.setDate
(int parameterIndex, Date x, Calendar cal)
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