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<?xml version="1.0" encoding="utf-8"?> <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"> <html xml:lang="en" lang="en" xmlns="http://www.w3.org/1999/xhtml"> <head> <meta http-equiv="Content-Type" content="text/html;charset=utf-8" /> <meta http-equiv="Content-Style-Type" content="text/css" /> <!-- MOTW-DISABLED saved from url=(0014)about:internet --> <title>NULL Values</title> <link rel="StyleSheet" href="css/sybaseiq.css" type="text/css" media="all" /> <link rel="StyleSheet" href="css/webworks.css" type="text/css" media="all" /> <script type="text/javascript" language="JavaScript1.2" src="wwhdata/common/context.js"></script> <script type="text/javascript" language="JavaScript1.2" src="wwhdata/common/towwhdir.js"></script> <script type="text/javascript" language="JavaScript1.2" src="wwhdata/common/wwhpagef.js"></script> <script type="text/javascript" language="JavaScript1.2"> <!-- var WebWorksRootPath = ""; // --> </script> <script type="text/javascript" language="JavaScript1.2"> <!-- // Set reference to top level help frame // var WWHFrame = WWHGetWWHFrame("", true); // --> </script> <script type="text/javascript" language="JavaScript1.2" src="scripts/expand.js"></script> </head> <body class="" style="background-color: #FFFFEE;" onload="WWHUpdate();" onunload="WWHUnload();" onkeydown="WWHHandleKeyDown((document.all||document.getElementById||document.layers)?event:null);" onkeypress="WWHHandleKeyPress((document.all||document.getElementById||document.layers)?event:null);" onkeyup="WWHHandleKeyUp((document.all||document.getElementById||document.layers)?event:null);"> <br /> <div class="WebWorks_Breadcrumbs" style="text-align: left;"> <a class="WebWorks_Breadcrumb_Link" href="sybaseiq.28.01.html#107744">22 The Sybase IQ Wire Protocol Driver</a> : NULL Values</div> <hr align="left" /> <blockquote> <div class="head_1"><a name="107744">NULL Values</a></div> <div class="Body"><a name="343520">When the Sybase IQ Wire Protocol driver establishes a connection, the driver sets the </a>Sybase database option ansinull to on. Setting ansinull to on ensures that the driver is compliant with the ANSI SQL standard, which makes developing cross-database applications easier. </div> <div class="Body"><a name="343521">By default, Sybase IQ does not evaluate NULL values in SQL equality (=), inequity (<>), or </a>aggregate function comparisons in an ANSI SQL-compliant manner. For example, the ANSI SQL specification defines that <span class="Syntax">col1=NULL</span> always evaluates to false:</div> <div class="syntax_first"><a name="107747">SELECT * FROM table WHERE col1 = NULL</a></div> <div class="Body"><a name="107749">Using the default database setting (ansinull=off), the same comparison evaluates to true </a>instead of false.</div> <div class="Body"><a name="107750">Setting ansinull to on changes the default database behavior so that SQL statements must </a>use <span class="Syntax">IS</span><span class="Syntax"> </span><span class="Syntax">NULL</span> instead of <span class="Syntax">=NULL</span>. For example, using the Sybase IQ Wire Protocol driver, if the value of col1 in the following statement is NULL, the comparison evaluates to true:</div> <div class="syntax_first"><a name="107751">SELECT * FROM table WHERE col1 IS NULL</a></div> <div class="Body"><a name="107752">In your application, you can restore the default Sybase IQ behavior for a connection in the </a>following ways:</div> <div class="list_bulleted_outer" style="margin-left: 0pt;"> <table border="0" cellspacing="0" cellpadding="0" summary=""> <tr style="vertical-align: baseline;"> <td> <div class="list_bulleted_inner" style="width: 18pt; white-space: nowrap;">â? </div> </td> <td width="100%"> <div class="list_bulleted_inner"><a name="107753">Use the Initialization String option to specify the SQL command </a><span class="Syntax">set</span><span class="Syntax"> </span><span class="Syntax">ANSINULL off</span>. For example, the following connection string ensures that the handling of NULL values is restored to the Sybase IQ default for the current connection:</div> </td> </tr> </table> </div> <div class="syntax_embed_first"><a name="107754">DSN=SYB TABLES;DB=PAYROLL;IS=set ANSINULL off</a></div> <div class="list_bulleted_outer" style="margin-left: 0pt;"> <table border="0" cellspacing="0" cellpadding="0" summary=""> <tr style="vertical-align: baseline;"> <td> <div class="list_bulleted_inner" style="width: 18pt; white-space: nowrap;">â? </div> </td> <td width="100%"> <div class="list_bulleted_inner"><a name="107755">Explicitly execute the following statement after the connection is established:</a></div> </td> </tr> </table> </div> <div class="syntax_embed_first"><a name="107756">SET ANSINULL OFF</a></div> <script type="text/javascript" language="JavaScript1.2"> <!-- // Clear related topics // WWHClearRelatedTopics(); document.writeln(WWHRelatedTopicsInlineHTML()); // --> </script> </blockquote> <script type="text/javascript" language="JavaScript1.2"> <!-- document.write(WWHRelatedTopicsDivTag() + WWHPopupDivTag() + WWHALinksDivTag()); // --> </script> </body> </html>
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