91 lines
6.1 KiB
HTML
91 lines
6.1 KiB
HTML
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<?xml version="1.0" encoding="UTF-8"?>
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<!DOCTYPE html
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PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
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<html lang="en-us" xml:lang="en-us">
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<head>
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<meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
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<meta name="security" content="public" />
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<meta http-equiv="PICS-Label" content='(PICS-1.1 "http://www.icra.org/ratingsv02.html" l gen true r (cz 1 lz 1 nz 1 oz 1 vz 1) "http://www.rsac.org/ratingsv01.html" l gen true r (n 0 s 0 v 0 l 0) "http://www.classify.org/safesurf/" l gen true r (SS~~000 1))' />
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<meta name="DC.Type" content="concept" />
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<meta name="DC.Title" content="SQLWarning" />
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<meta name="abstract" content="Methods in some interfaces generate an SQLWarning object if the methods cause a database access warning." />
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<meta name="description" content="Methods in some interfaces generate an SQLWarning object if the methods cause a database access warning." />
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<meta name="DC.Relation" scheme="URI" content="exceptin.htm" />
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<meta name="DC.Relation" scheme="URI" content="exceptions.htm" />
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<meta name="DC.Relation" scheme="URI" content="datatruk.htm" />
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<meta name="copyright" content="(C) Copyright IBM Corporation 2006" />
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<meta name="DC.Rights.Owner" content="(C) Copyright IBM Corporation 2006" />
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<meta name="DC.Format" content="XHTML" />
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<meta name="DC.Identifier" content="sqlwarng" />
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<meta name="DC.Language" content="en-us" />
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<!-- All rights reserved. Licensed Materials Property of IBM -->
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<!-- US Government Users Restricted Rights -->
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<!-- Use, duplication or disclosure restricted by -->
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<!-- GSA ADP Schedule Contract with IBM Corp. -->
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<link rel="stylesheet" type="text/css" href="./ibmdita.css" />
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<link rel="stylesheet" type="text/css" href="./ic.css" />
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<title>SQLWarning</title>
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</head>
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<body id="sqlwarng"><a name="sqlwarng"><!-- --></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">SQLWarning</h1>
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<div><p>Methods in some interfaces generate an SQLWarning object if the
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methods cause a database access warning.</p>
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<p>Methods in the following interfaces can generate an SQLWarning:</p>
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<ul><li>Connection</li>
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<li>Statement and its subtypes, PreparedStatement and CallableStatement</li>
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<li>ResultSet</li>
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</ul>
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<p> When a method generates an SQLWarning object, the caller is not informed
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that a data access warning has occurred. The getWarnings method must be called
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on the appropriate object to retrieve the SQLWarning object. However, the
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DataTruncation subclass of SQLWarning may be thrown in some circumstances.
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It should be noted that the native JDBC driver opts to ignore some database-generated
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warnings for increased efficiency. For example, a warning is generated by
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the system when you attempt to retrieve data beyond the end of a ResultSet
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through the ResultSet.next method. In this case, the next method is defined
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to return false instead of true, informing you of the error. It is unnecessary
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to create an object to restate this, so the warning is simply ignored. </p>
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<p>If multiple data access warnings occur, they are chained to the first one
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and can be retrieved by calling the SQLWarning.getNextWarning method. If there
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are no more warnings in the chain, getNextWarning returns <samp class="codeph">null</samp>.</p>
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<p>Subsequent SQLWarning objects continue to be added to the chain until the
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next statement is processed or, in the case of a ResultSet object, when the
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cursor is repositioned. As a result, all SQLWarning objects in the chain are
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removed.</p>
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<p>Using Connection, Statement, and ResultSet objects can cause SQLWarnings
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to be generated. SQLWarnings are informational messages indicating that while
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a particular operation has completed successfully, there might be other information
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of which you should be aware. SQLWarnings are an extension of the SQLException
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class, but they are not thrown. They are instead attached to the object that
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causes their generation. When an SQLWarning is generated, nothing happens
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to inform the application that the warning has been generated. Your application
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must actively request warning information.</p>
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<p>Like SQLExceptions, SQLWarnings can be chained to one another. You can
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call the clearWarnings method on a Connection, Statement, or ResultSet object
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to clear the warnings for that object.</p>
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<div class="note"><span class="notetitle">Note:</span> Calling the clearWarnings method does not clear all warnings. It only
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clears the warnings that are associated with a particular object.</div>
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<p>The JDBC driver clears SQLWarning objects at specific times
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if you do not clear them manually. SQLWarning objects are cleared when the
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following actions are taken:</p>
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<ul><li>For the Connection interface, warnings are cleared on the creation of
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a new Statement, PreparedStatement, or CallableStatement object.</li>
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<li>For the Statement interface, warnings are cleared when the next statement
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is processed (or when the statement is processed again for PreparedStatements
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and CallableStatements).</li>
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<li>For the ResultSet interface, warnings are cleared when the cursor is repositioned. </li>
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</ul>
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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="exceptin.htm" title="The Java language uses exceptions to provide error-handling capabilities for its programs. An exception is an event that occurs when you run your program that disrupts the normal flow of instructions.">Exceptions</a></div>
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</div>
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<div class="relconcepts"><strong>Related concepts</strong><br />
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<div><a href="exceptions.htm" title="The SQLException class and its subtypes provide information about errors and warnings that occur while a data source is being accessed.">SQLException</a></div>
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<div><a href="datatruk.htm" title="DataTruncation is a subclass of SQLWarning. While SQLWarnings are not thrown, DataTruncation objects are sometimes thrown and attached like other SQLWarning objects. Silent truncation occurs when the size of a column exceeds the size specified by the setMaxFieldSize statement method, but no warning or exception is reported.">DataTruncation and silent truncation</a></div>
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</div>
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</div>
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</body>
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</html>
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