WebLogic Server 5.1.0 API Reference

weblogic.db.jdbc
Class QueryDataSet

java.lang.Object
  |
  +--weblogic.db.jdbc.DataSet
        |
        +--weblogic.db.jdbc.QueryDataSet

public class QueryDataSet

extends DataSet

A QueryDataSet holds the results of an arbitrary SQL query. The results are available as a collection of Records accessible by an integer index. You can add new records and modify existing records of a QueryDataSet, but the additions and changes cannot be saved to the database. If you wish to save such changes, use a TableDataSet instead.

A QueryDataSet is constructed in the context of a Connection or a ResultSet.

The following example retrieves the query results into ds.

    QueryDataSet ds = new QueryDataSet(conn, "select * from tableA where f1 = 34");
    ds.fetchRecords();
    ds.close()  // This must be called
 

Pass an argument to fetchRecords() to set the size of the fetch. This example retrieves no more than the first 20 records of the query into ds and discards the remaining records by closing the DataSet.

    QueryDataSet ds = new QueryDataSet(conn, "select * from tableA where f1 = 34");
    ds.fetchRecords(20)
    ds.close()  // This must be called
 

The last example retrieves 100 records at a time into ds, does something, and then removes the records from the DataSet. This approach is useful for dealing with large query results.

    QueryDataSet ds = new QueryDataSet(conn, "select * from tableA, tableB where "
                                       + "tableA.f1 = tableB.f1");
    while (!ds.allRecordsRetrieved()) {
      ds.fetchRecords(100);
      // Do something with the 100 records...
      ds.clearRecords();
    }
    ds.close()  // This must be called
 

For more implementation and usage, see the Developers Guide.

Author:

Copyright (c) 1995-1998 by WebLogic, Inc. All Rights Reserved., Copyright (c) 1998-1999 by BEA Systems, Inc. All Rights Reserved.
Copyright © 2000 BEA Systems, Inc. All Rights Reserved.

See Also:

DataSet, SelectStmt, TableDataSet, Serialized Form

Fields inherited from class weblogic.db.jdbc.DataSet

cached, resetable, resultval, stmt

Constructor Summary

QueryDataSet()
Private - used for serialization

QueryDataSet(java.sql.Connection conn, SelectStmt stmt)
QueryDataSet constructor.

QueryDataSet(java.sql.Connection conn, java.lang.String sqlstr)
QueryDataSet constructor.

QueryDataSet(java.sql.ResultSet results)
QueryDataSet constructor.

Method Summary

java.lang.String	getSelectString() Returns the SQL SELECT statement used to populate a QueryDataSet.
java.sql.ResultSet	resultSet() Returns the JDBC ResultSet associated with a QueryDataSet.

Methods inherited from class weblogic.db.jdbc.DataSet

addRecord, allRecordsRetrieved, clearRecords, close, connection, containsRecord, destroy, fetchRecords, fetchRecords, fetchRecords, getRecord, getResultSet, initialize, lastFetchSize, maxColumnWidths, readObject, releaseRecords, removeRecord, reset, schema, size, toString, writeObject

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait

Constructor Detail

QueryDataSet

public QueryDataSet(java.sql.ResultSet results)
             throws java.sql.SQLException,
                    DataSetException

QueryDataSet constructor. The reset() method is unavailable on a QueryDataSet created with this constructor. Also, QueryDataSet.close() will not close the ResultSet argument of this constructor.

Parameters:

results - JDBC ResultSet

sqlstr - SQL query string to specify data

Throws:

java.sql.SQLException - if there is a SQL error

DataSetException - if there is an error creating the DataSet

QueryDataSet

public QueryDataSet(java.sql.Connection conn,
                    java.lang.String sqlstr)
             throws java.sql.SQLException,
                    DataSetException

QueryDataSet constructor. This constructor takes as an argument a string that is an arbitrary SQL statement.

Parameters:

conn - Connection object

sqlstr - SQL query string to specify data

Throws:

java.sql.SQLException - if there is a SQL error

DataSetException - if there is an error creating the DataSet

QueryDataSet

public QueryDataSet(java.sql.Connection conn,
                    SelectStmt stmt)
             throws java.sql.SQLException,
                    DataSetException

QueryDataSet constructor. Use a SelectStmt as an argument to set a SQL statement for this constructor. The SelectStmt class has methods for automatic SQL generation.

Parameters:

db - Connection object

stmt - SelectStmt object to specify data

Throws:

java.sql.SQLException - if there is a SQL error

DataSetException - if there is an error creating the DataSet

QueryDataSet

public QueryDataSet()

Private - used for serialization

Method Detail

getSelectString

public java.lang.String getSelectString()

Returns the SQL SELECT statement used to populate a QueryDataSet.

Returns:

SQL SELECT statement

Overrides:

getSelectString in class DataSet

resultSet

public java.sql.ResultSet resultSet()
                             throws java.sql.SQLException,
                                    DataSetException

Returns the JDBC ResultSet associated with a QueryDataSet.

Returns:

JDBC ResultSet

Throws:

java.sql.SQLException - if there is a SQL error

DataSetException - if there is an error creating the DataSet

Overrides:

resultSet in class DataSet