182 lines
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HTML
182 lines
12 KiB
HTML
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<meta name="DC.Title" content="Enhanced JDBC functions for i5/OS Version 5 Release 2" />
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<meta name="abstract" content="Several JDBC functions were enhanced for i5/OS Version 5 Release 2." />
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<link rel="stylesheet" type="text/css" href="./ic.css" />
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<title>Enhanced JDBC functions for i5/OS Version 5 Release 2</title>
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<body id="rzahhjdbcenhancev5r2"><a name="rzahhjdbcenhancev5r2"><!-- --></a>
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<!-- Java sync-link --><script language="Javascript" src="../rzahg/synch.js" type="text/javascript"></script>
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<h1 class="topictitle1">Enhanced JDBC functions for i5/OS Version 5 Release 2</h1>
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<div><p>Several JDBC functions were enhanced for i5/OS™ Version 5 Release 2.</p>
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<div class="section"><p>Enhanced JDBC functions for i5/OS Version 5 Release 2 include:</p>
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<ul><li> <a href="#rzahhjdbcenhancev5r2__forupdate">Removal of 'FOR UPDATE'
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restriction</a></li>
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<li> <a href="#rzahhjdbcenhancev5r2__datatruncation">Change in data truncation</a></li>
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<li> <a href="#rzahhjdbcenhancev5r2__callablestatementmethods">Get and modify
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columns and parameters by name</a></li>
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<li> <a href="#rzahhjdbcenhancev5r2__autogenerate">Retrieve auto-generated
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keys</a></li>
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<li> <a href="#rzahhjdbcenhancev5r2__as400jdbcstatementmethods">Improved
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performance when running SQL insert statements in a batch</a></li>
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<li> <a href="#rzahhjdbcenhancev5r2__resultsetgetrow">Enhanced support for
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ResultSet.getRow()</a></li>
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<li> <a href="#rzahhjdbcenhancev5r2__mixedcasecolumn">Improved support for
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using mixed cases in column names</a></li>
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<li> <a href="#rzahhjdbcenhancev5r2__holdability">Specify holdability for
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Statements, CallableStatements, and PreparedStatements</a></li>
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<li> <a href="#rzahhjdbcenhancev5r2__transactionisolation">Enhanced transaction
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isolation support</a></li>
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</ul>
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</div>
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<div class="section" id="rzahhjdbcenhancev5r2__forupdate"><a name="rzahhjdbcenhancev5r2__forupdate"><!-- --></a><dl><dt class="dlterm"><strong>Removal of the 'FOR UPDATE' restriction</strong></dt>
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<dd>You no longer need to specify FOR UPDATE on your SELECT statements in
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order to guarantee an updatable cursor. When connecting to V5R1 and later
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versions of i5/OS, IBM<sup>®</sup> Toolbox
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for Java™ honors
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whatever concurrency you pass in when you create statements. The default
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continues to be a read-only cursor if you do not specify a concurrency.</dd>
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</dl>
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</div>
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<div class="section" id="rzahhjdbcenhancev5r2__datatruncation"><a name="rzahhjdbcenhancev5r2__datatruncation"><!-- --></a><dl><dt class="dlterm"><strong>Data truncation throws exceptions only when truncated character data
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is written to the database</strong></dt>
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<dd>Data truncation rules for IBM Toolbox for Java now are the same as those for the <a href="jdbc.htm#jdbc">IBM Developer Kit for Java JDBC driver</a>. For more information,
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see <a href="jdbcproperties.htm#jdbcproperties__other">IBM Toolbox for Java JDBC
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properties</a>.</dd>
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</dl>
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</div>
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<div class="section" id="rzahhjdbcenhancev5r2__callablestatementmethods"><a name="rzahhjdbcenhancev5r2__callablestatementmethods"><!-- --></a><dl><dt class="dlterm"><strong>Get and modify columns and parameters by name</strong></dt>
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<dd>New methods allow you to get and update information by column name in <a href="jdbcrs.htm#jdbcrs">ResultSet</a> and to get and set information
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by parameter name in <a href="jdbccst.htm#jdbccst">CallableStatement</a>.
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For example, in ResultSet, where you previously used the following: <pre> ResultSet rs = statement.executeQuery( SELECT * FROM MYCOLLECTION/MYTABLE );
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rs.getString(1);</pre>
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<p>You can now use:</p>
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<pre> ResultSet rs = statement.executeQuery( SELECT * FROM MYCOLLECTION/MYTABLE );
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rs.getString( 'STUDENTS' );</pre>
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<p>Be aware that accessing
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parameters by their index results in better performance than accessing them
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by their name. You can also specify parameter names to set in CallableStatement.
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Where you might have used the following in CallableStatement:</p>
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<pre> CallableStatement cs = connection.prepareCall( CALL MYPGM (?) );
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cs.setString( 1 );</pre>
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<p>You can now use:</p>
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<pre> CallableStatement cs = connection.prepareCall( CALL MYPGM (?) );
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cs.setString( 'PARAM_1' );</pre>
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<p>To use these new methods,
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you need JDBC 3.0 or later and the Java 2 Platform, version 1.4 (either the
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Standard or the Enterprise Edition).</p>
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</dd>
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</dl>
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</div>
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<div class="section" id="rzahhjdbcenhancev5r2__autogenerate"><a name="rzahhjdbcenhancev5r2__autogenerate"><!-- --></a><dl><dt class="dlterm"><strong>Retrieve auto-generated keys</strong></dt>
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<dd>The getGeneratedKeys() method on <a href="javadoc/com/ibm/as400/access/AS400JDBCStatement.html">AS400JDBCStatement</a> retrieves any auto-generated keys
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created as a result of executing that Statement object. When the Statement
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object does not generate any keys, an empty ResultSet object is returned.
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Currently the server supports returning only one auto-generated key (the
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key for the last inserted row). The following example shows how you might
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insert a value into a table then get the auto-generated key: <pre> Statement s =
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statement.executeQuery("INSERT INTO MYSCHOOL/MYSTUDENTS (FIRSTNAME) VALUES ('JOHN'");
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ResultSet rs = s.getGeneratedKeys();
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// Currently the iSeries server supports returning only one auto-generated
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// key -- the key for the last inserted row.
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rs.next();
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String autoGeneratedKey = rs.getString(1);
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// Use the auto-generated key, for example, as the primary key in another table</pre>
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<p>To
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retrieve auto-generated keys, you need JDBC 3.0 or later, and the Java 2
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Platform, version 1.4 (either the Standard or the Enterprise Edition). Retrieving
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auto-generated keys also requires connecting to a V5R2 or later version of i5/OS.</p>
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</dd>
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</dl>
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</div>
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<div class="section" id="rzahhjdbcenhancev5r2__as400jdbcstatementmethods"><a name="rzahhjdbcenhancev5r2__as400jdbcstatementmethods"><!-- --></a><dl><dt class="dlterm"><strong>Improved performance when running SQL insert statements in a batch</strong></dt>
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<dd>Performance of running SQL insert statements in a batch has been improved.
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Run SQL statements in a batch by using the different addBatch() methods available
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in <a href="javadoc/com/ibm/as400/access/AS400JDBCStatement.html">AS400JDBCStatement</a>, <a href="javadoc/com/ibm/as400/access/AS400JDBCPreparedStatement.html">AS400JDBCPreparedStatement</a>, and <a href="javadoc/com/ibm/as400/access/AS400JDBCCallableStatement.html">AS400JDBCCallableStatement</a>. Enhanced batch support affects
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only insert requests. For example, using batch support to process several
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inserts involves only one pass to the server. However, using batch support
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to process an insert, and update, and a delete sends each request individually. <p>To
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use batch support, you need JDBC 2.0 or later and the Java 2
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Platform, version 1.2 (either the Standard or the Enterprise Edition).</p>
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</dd>
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</dl>
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</div>
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<div class="section" id="rzahhjdbcenhancev5r2__resultsetgetrow"><a name="rzahhjdbcenhancev5r2__resultsetgetrow"><!-- --></a><dl><dt class="dlterm"><strong>Enhanced support for ResultSet.getRow()</strong></dt>
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<dd>Previously, the IBM Toolbox for Java JDBC driver was limited in its support
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for the getRow() method in <a href="jdbcrs.htm#jdbcrs">ResultSet</a>.
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Specifically, using ResultSet.last(), ResultSet.afterLast(), and ResultSet.absolute()
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with a negative value made the current row number not available. The previous
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restrictions are lifted, making this method fully functional.</dd>
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</dl>
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</div>
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<div class="section" id="rzahhjdbcenhancev5r2__mixedcasecolumn"><a name="rzahhjdbcenhancev5r2__mixedcasecolumn"><!-- --></a><dl><dt class="dlterm"><strong>Using mixed case in column names</strong></dt>
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<dd>IBM Toolbox
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for Java methods
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must match either column names provided by the user or column names provided
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by the application with the names that are on the database table. In either
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case, when a column name is not enclosed in quotes, IBM Toolbox for Java changes the name to uppercase characters
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before matching it against the names on the server. When the column name
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is enclosed in quotes, it must exactly match the name on the server or IBM Toolbox
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for Java throws
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an exception.</dd>
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</dl>
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</div>
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<div class="section" id="rzahhjdbcenhancev5r2__holdability"><a name="rzahhjdbcenhancev5r2__holdability"><!-- --></a><dl><dt class="dlterm"><strong>Specify holdability in created Statements, CallableStatements, and
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PreparedStatements</strong></dt>
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<dd>New methods in <a href="javadoc/com/ibm/as400/access/AS400JDBCConnection.html">AS400JDBCConnection</a> allow you to specify the holdability
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for Statements, CallableStatements, and PreparedStatements that you create.
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Holdability determines whether cursors are held open or closed when committing
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the transaction. You can now have a statement that has a different holdability
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than its connection object. Also, connection objects can have multiple open
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statement objects, each with a different specified holdability. Calling commit
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causes each statement to be handled according to the holdability specified
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for that statement. <p>Holdability is derived in the following order of precedence:</p>
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<ol><li>Holdability specified on statement creation by using the Connection class
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methods createStatement(), prepareCall(), or prepareStatement().</li>
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<li>Holdability specified by using Connection.setHoldability(int).</li>
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<li>Holdability specified by the IBM Toolbox for Java <a href="jdbcproperties.htm#jdbcproperties__server">JDBC
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cursor hold property</a> (when methods in 1. or 2. are not used)</li>
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</ol>
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<p>To use these methods, you need JDBC 3.0 or later, and the Java 2
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Platform, version 1.4 (either the Standard or the Enterprise Edition). Also,
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servers running a V5R1 or earlier version of i5/OS are able to use only the holdability
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specified by the JDBC cursor hold property.</p>
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</dd>
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</dl>
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</div>
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<div class="section" id="rzahhjdbcenhancev5r2__transactionisolation"><a name="rzahhjdbcenhancev5r2__transactionisolation"><!-- --></a><dl><dt class="dlterm"><strong>Enhanced transaction isolation support</strong></dt>
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<dd>The IBM Toolbox
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for Java JDBC
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driver now features support for switching to a transaction isolation level
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of *NONE after a connection is made. Before V5R2, the IBM Toolbox for Java JDBC driver threw an exception when
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switching to *NONE after making a connection.</dd>
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</dl>
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</div>
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</div>
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<div>
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<div class="familylinks">
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<div class="parentlink"><strong>Parent topic:</strong> <a href="jdbc2.htm" title="JDBC is an application programming interface (API) included in the Java platform that enables Java programs to connect to a wide range of databases.">JDBC</a></div>
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</div>
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</div>
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</body>
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</html> |