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Overview
| Comment: | Update the null-handling document to show how SQL Anywhere and Borland Interbase deal with NULLs. (CVS 1043) |
|---|---|
| Downloads: | Tarball | ZIP archive | SQL archive |
| Timelines: | family | ancestors | descendants | both | trunk |
| Files: | files | file ages | folders |
| SHA1: |
9a87f2f326d7fc8bb9f832d0e3fd3114 |
| User & Date: | drh 2003-07-01 01:16:30 |
Context
|
2003-07-01
| ||
| 18:13 | Make sure indices in ATTACH-ed databases are put into the right hash table. Ticket #354. (CVS 1044) (check-in: eb458283 user: drh tags: trunk) | |
| 01:16 | Update the null-handling document to show how SQL Anywhere and Borland Interbase deal with NULLs. (CVS 1043) (check-in: 9a87f2f3 user: drh tags: trunk) | |
|
2003-06-30
| ||
| 10:36 | Documentation change: refer users to the wiki for additional unsupported features rather than have them send me e-mail. (CVS 1042) (check-in: a3920b08 user: drh tags: trunk) | |
Changes
Changes to www/nulls.tcl.
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#
# Run this script to generated a nulls.html output file
#
set rcsid {$Id: nulls.tcl,v 1.1 2002/09/02 14:11:04 drh Exp $}
puts {<html>
<head>
<title>NULL Handling In SQLite Versus Other Database Engines</title>
</head>
<body bgcolor="white">
<h1 align="center">
................................................................................
<tr><th>  </th>
<th>SQLite</th>
<th>PostgreSQL</th>
<th>Oracle</th>
<th>Informix</th>
<th>DB2</th>
<th>MS-SQL</th>
<th>MySQL</th>
<th>OCELOT</th>
<th>Firebird</th>
</tr>
<tr><td>Adding anything to null gives null</td>
<td valign="center" align="center" bgcolor="#a9c7a9">Yes</td>
<td valign="center" align="center" bgcolor="#a9c7a9">Yes</td>
<td valign="center" align="center" bgcolor="#a9c7a9">Yes</td>
<td valign="center" align="center" bgcolor="#a9c7a9">Yes</td>
<td valign="center" align="center" bgcolor="#a9c7a9">Yes</td>
<td valign="center" align="center" bgcolor="#a9c7a9">Yes</td>
<td valign="center" align="center" bgcolor="#a9c7a9">Yes</td>
<td valign="center" align="center" bgcolor="#a9c7a9">Yes</td>
<td valign="center" align="center" bgcolor="#a9c7a9">Yes</td>
</tr>
<tr><td>Multiplying null by zero gives null</td>
<td valign="center" align="center" bgcolor="#a9c7a9">Yes</td>
<td valign="center" align="center" bgcolor="#a9c7a9">Yes</td>
<td valign="center" align="center" bgcolor="#a9c7a9">Yes</td>
<td valign="center" align="center" bgcolor="#a9c7a9">Yes</td>
<td valign="center" align="center" bgcolor="#a9c7a9">Yes</td>
<td valign="center" align="center" bgcolor="#a9c7a9">Yes</td>
<td valign="center" align="center" bgcolor="#a9c7a9">Yes</td>
<td valign="center" align="center" bgcolor="#a9c7a9">Yes</td>
<td valign="center" align="center" bgcolor="#a9c7a9">Yes</td>
</tr>
<tr><td>nulls are distinct in a UNIQUE index</td>
<td valign="center" align="center" bgcolor="#a9c7a9">Yes</td>
<td valign="center" align="center" bgcolor="#a9c7a9">Yes</td>
<td valign="center" align="center" bgcolor="#a9c7a9">Yes</td>
<td valign="center" align="center" bgcolor="#c7a9a9">No</td>
<td valign="center" align="center" bgcolor="#a9c7a9">Yes</td>
<td valign="center" align="center" bgcolor="#c7a9a9">No</td>
<td valign="center" align="center" bgcolor="#a9c7a9">Yes</td>
<td valign="center" align="center" bgcolor="#a9c7a9">Yes</td>
<td valign="center" align="center" bgcolor="#a9c7a9">Yes</td>
</tr>
<tr><td>nulls are distinct in SELECT DISTINCT</td>
<td valign="center" align="center" bgcolor="#c7a9a9">No</td>
<td valign="center" align="center" bgcolor="#c7a9a9">No</td>
<td valign="center" align="center" bgcolor="#c7a9a9">No</td>
<td valign="center" align="center" bgcolor="#c7a9a9">No</td>
<td valign="center" align="center" bgcolor="#c7a9a9">No</td>
<td valign="center" align="center" bgcolor="#c7a9a9">No</td>
<td valign="center" align="center" bgcolor="#c7a9a9">No</td>
<td valign="center" align="center" bgcolor="#a9c7a9">Yes</td>
<td valign="center" align="center" bgcolor="#aaaad2">(Note 1)</td>
</tr>
<tr><td>nulls are distinct in a UNION</td>
<td valign="center" align="center" bgcolor="#c7a9a9">No</td>
<td valign="center" align="center" bgcolor="#c7a9a9">No</td>
<td valign="center" align="center" bgcolor="#c7a9a9">No</td>
<td valign="center" align="center" bgcolor="#c7a9a9">No</td>
<td valign="center" align="center" bgcolor="#c7a9a9">No</td>
<td valign="center" align="center" bgcolor="#c7a9a9">No</td>
<td valign="center" align="center" bgcolor="#aaaad2">(Note 3)</td>
<td valign="center" align="center" bgcolor="#a9c7a9">Yes</td>
<td valign="center" align="center" bgcolor="#aaaad2">(Note 1)</td>
</tr>
<tr><td>"CASE WHEN null THEN 1 ELSE 0 END" is 0?</td>
<td valign="center" align="center" bgcolor="#a9c7a9">Yes</td>
<td valign="center" align="center" bgcolor="#a9c7a9">Yes</td>
<td valign="center" align="center" bgcolor="#a9c7a9">Yes</td>
<td valign="center" align="center" bgcolor="#a9c7a9">Yes</td>
<td valign="center" align="center" bgcolor="#a9c7a9">Yes</td>
<td valign="center" align="center" bgcolor="#a9c7a9">Yes</td>
<td valign="center" align="center" bgcolor="#a9c7a9">Yes</td>
<td valign="center" align="center" bgcolor="#a9c7a9">Yes</td>
<td valign="center" align="center" bgcolor="#aaaad2">(Note 2)</td>
</tr>
<tr><td>"null OR true" is true</td>
<td valign="center" align="center" bgcolor="#a9c7a9">Yes</td>
<td valign="center" align="center" bgcolor="#a9c7a9">Yes</td>
<td valign="center" align="center" bgcolor="#a9c7a9">Yes</td>
<td valign="center" align="center" bgcolor="#a9c7a9">Yes</td>
<td valign="center" align="center" bgcolor="#a9c7a9">Yes</td>
<td valign="center" align="center" bgcolor="#a9c7a9">Yes</td>
<td valign="center" align="center" bgcolor="#a9c7a9">Yes</td>
<td valign="center" align="center" bgcolor="#c7a9a9">No</td>
<td valign="center" align="center" bgcolor="#a9c7a9">Yes</td>
</tr>
<tr><td>"not (null AND false)" is true</td>
<td valign="center" align="center" bgcolor="#a9c7a9">Yes</td>
<td valign="center" align="center" bgcolor="#a9c7a9">Yes</td>
<td valign="center" align="center" bgcolor="#a9c7a9">Yes</td>
<td valign="center" align="center" bgcolor="#a9c7a9">Yes</td>
<td valign="center" align="center" bgcolor="#a9c7a9">Yes</td>
<td valign="center" align="center" bgcolor="#a9c7a9">Yes</td>
<td valign="center" align="center" bgcolor="#c7a9a9">No</td>
<td valign="center" align="center" bgcolor="#c7a9a9">No</td>
<td valign="center" align="center" bgcolor="#a9c7a9">Yes</td>
</tr>
</table>
<table border=0 align="right" cellpadding=0 cellspacing=0>
<tr>
<td valign="top" rowspan=3>Notes: </td>
<td>1. </td>
<td>Firebird omits all NULLs from SELECT DISTINCT and from UNION.</td>
</tr>
<tr><td>2. </td>
<td>Test data unavailable.</td></tr>
<tr><td>3. </td>
<td>The version of MySQL tested (3.23.41) does not support UNION.</td></tr>
</table>
<br clear="both">
<p> </p>
<p>
The following script was used to gather information for the table
above.
|
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|
#
# Run this script to generated a nulls.html output file
#
set rcsid {$Id: nulls.tcl,v 1.2 2003/07/01 01:16:30 drh Exp $}
puts {<html>
<head>
<title>NULL Handling In SQLite Versus Other Database Engines</title>
</head>
<body bgcolor="white">
<h1 align="center">
................................................................................
<tr><th>  </th>
<th>SQLite</th>
<th>PostgreSQL</th>
<th>Oracle</th>
<th>Informix</th>
<th>DB2</th>
<th>MS-SQL</th>
</tr>
<tr><td>Adding anything to null gives null</td>
<td valign="center" align="center" bgcolor="#a9c7a9">Yes</td>
<td valign="center" align="center" bgcolor="#a9c7a9">Yes</td>
<td valign="center" align="center" bgcolor="#a9c7a9">Yes</td>
<td valign="center" align="center" bgcolor="#a9c7a9">Yes</td>
<td valign="center" align="center" bgcolor="#a9c7a9">Yes</td>
<td valign="center" align="center" bgcolor="#a9c7a9">Yes</td>
</tr>
<tr><td>Multiplying null by zero gives null</td>
<td valign="center" align="center" bgcolor="#a9c7a9">Yes</td>
<td valign="center" align="center" bgcolor="#a9c7a9">Yes</td>
<td valign="center" align="center" bgcolor="#a9c7a9">Yes</td>
<td valign="center" align="center" bgcolor="#a9c7a9">Yes</td>
<td valign="center" align="center" bgcolor="#a9c7a9">Yes</td>
<td valign="center" align="center" bgcolor="#a9c7a9">Yes</td>
</tr>
<tr><td>nulls are distinct in a UNIQUE index</td>
<td valign="center" align="center" bgcolor="#a9c7a9">Yes</td>
<td valign="center" align="center" bgcolor="#a9c7a9">Yes</td>
<td valign="center" align="center" bgcolor="#a9c7a9">Yes</td>
<td valign="center" align="center" bgcolor="#c7a9a9">No</td>
<td valign="center" align="center" bgcolor="#a9c7a9">Yes</td>
<td valign="center" align="center" bgcolor="#c7a9a9">No</td>
</tr>
<tr><td>nulls are distinct in SELECT DISTINCT</td>
<td valign="center" align="center" bgcolor="#c7a9a9">No</td>
<td valign="center" align="center" bgcolor="#c7a9a9">No</td>
<td valign="center" align="center" bgcolor="#c7a9a9">No</td>
<td valign="center" align="center" bgcolor="#c7a9a9">No</td>
<td valign="center" align="center" bgcolor="#c7a9a9">No</td>
<td valign="center" align="center" bgcolor="#c7a9a9">No</td>
</tr>
<tr><td>nulls are distinct in a UNION</td>
<td valign="center" align="center" bgcolor="#c7a9a9">No</td>
<td valign="center" align="center" bgcolor="#c7a9a9">No</td>
<td valign="center" align="center" bgcolor="#c7a9a9">No</td>
<td valign="center" align="center" bgcolor="#c7a9a9">No</td>
<td valign="center" align="center" bgcolor="#c7a9a9">No</td>
<td valign="center" align="center" bgcolor="#c7a9a9">No</td>
</tr>
<tr><td>"CASE WHEN null THEN 1 ELSE 0 END" is 0?</td>
<td valign="center" align="center" bgcolor="#a9c7a9">Yes</td>
<td valign="center" align="center" bgcolor="#a9c7a9">Yes</td>
<td valign="center" align="center" bgcolor="#a9c7a9">Yes</td>
<td valign="center" align="center" bgcolor="#a9c7a9">Yes</td>
<td valign="center" align="center" bgcolor="#a9c7a9">Yes</td>
<td valign="center" align="center" bgcolor="#a9c7a9">Yes</td>
</tr>
<tr><td>"null OR true" is true</td>
<td valign="center" align="center" bgcolor="#a9c7a9">Yes</td>
<td valign="center" align="center" bgcolor="#a9c7a9">Yes</td>
<td valign="center" align="center" bgcolor="#a9c7a9">Yes</td>
<td valign="center" align="center" bgcolor="#a9c7a9">Yes</td>
<td valign="center" align="center" bgcolor="#a9c7a9">Yes</td>
<td valign="center" align="center" bgcolor="#a9c7a9">Yes</td>
</tr>
<tr><td>"not (null AND false)" is true</td>
<td valign="center" align="center" bgcolor="#a9c7a9">Yes</td>
<td valign="center" align="center" bgcolor="#a9c7a9">Yes</td>
<td valign="center" align="center" bgcolor="#a9c7a9">Yes</td>
<td valign="center" align="center" bgcolor="#a9c7a9">Yes</td>
<td valign="center" align="center" bgcolor="#a9c7a9">Yes</td>
<td valign="center" align="center" bgcolor="#a9c7a9">Yes</td>
</tr>
</table>
<table border=1 cellpadding=5 width="100%">
<tr><th>  </th>
<th>MySQL</th>
<th>OCELOT</th>
<th>Firebird</th>
<th>SQL Anywhere</th>
<th>Borland Interbase</th>
</tr>
<tr><td>Adding anything to null gives null</td>
<td valign="center" align="center" bgcolor="#a9c7a9">Yes</td>
<td valign="center" align="center" bgcolor="#a9c7a9">Yes</td>
<td valign="center" align="center" bgcolor="#a9c7a9">Yes</td>
<td valign="center" align="center" bgcolor="#a9c7a9">Yes</td>
<td valign="center" align="center" bgcolor="#a9c7a9">Yes</td>
</tr>
<tr><td>Multiplying null by zero gives null</td>
<td valign="center" align="center" bgcolor="#a9c7a9">Yes</td>
<td valign="center" align="center" bgcolor="#a9c7a9">Yes</td>
<td valign="center" align="center" bgcolor="#a9c7a9">Yes</td>
<td valign="center" align="center" bgcolor="#a9c7a9">Yes</td>
<td valign="center" align="center" bgcolor="#a9c7a9">Yes</td>
</tr>
<tr><td>nulls are distinct in a UNIQUE index</td>
<td valign="center" align="center" bgcolor="#a9c7a9">Yes</td>
<td valign="center" align="center" bgcolor="#a9c7a9">Yes</td>
<td valign="center" align="center" bgcolor="#a9c7a9">Yes</td>
<td valign="center" align="center" bgcolor="#aaaad2">(Note 4)</td>
<td valign="center" align="center" bgcolor="#aaaad2">(Note 4)</td>
</tr>
<tr><td>nulls are distinct in SELECT DISTINCT</td>
<td valign="center" align="center" bgcolor="#c7a9a9">No</td>
<td valign="center" align="center" bgcolor="#a9c7a9">Yes</td>
<td valign="center" align="center" bgcolor="#aaaad2">(Note 1)</td>
<td valign="center" align="center" bgcolor="#c7a9a9">No</td>
<td valign="center" align="center" bgcolor="#c7a9a9">No</td>
</tr>
<tr><td>nulls are distinct in a UNION</td>
<td valign="center" align="center" bgcolor="#aaaad2">(Note 3)</td>
<td valign="center" align="center" bgcolor="#a9c7a9">Yes</td>
<td valign="center" align="center" bgcolor="#aaaad2">(Note 1)</td>
<td valign="center" align="center" bgcolor="#c7a9a9">No</td>
<td valign="center" align="center" bgcolor="#c7a9a9">No</td>
</tr>
<tr><td>"CASE WHEN null THEN 1 ELSE 0 END" is 0?</td>
<td valign="center" align="center" bgcolor="#a9c7a9">Yes</td>
<td valign="center" align="center" bgcolor="#a9c7a9">Yes</td>
<td valign="center" align="center" bgcolor="#aaaad2">(Note 2)</td>
<td valign="center" align="center" bgcolor="#a9c7a9">Yes</td>
<td valign="center" align="center" bgcolor="#aaaad2">(Note 5)</td>
</tr>
<tr><td>"null OR true" is true</td>
<td valign="center" align="center" bgcolor="#a9c7a9">Yes</td>
<td valign="center" align="center" bgcolor="#c7a9a9">No</td>
<td valign="center" align="center" bgcolor="#a9c7a9">Yes</td>
<td valign="center" align="center" bgcolor="#a9c7a9">Yes</td>
<td valign="center" align="center" bgcolor="#a9c7a9">Yes</td>
</tr>
<tr><td>"not (null AND false)" is true</td>
<td valign="center" align="center" bgcolor="#c7a9a9">No</td>
<td valign="center" align="center" bgcolor="#c7a9a9">No</td>
<td valign="center" align="center" bgcolor="#a9c7a9">Yes</td>
<td valign="center" align="center" bgcolor="#a9c7a9">Yes</td>
<td valign="center" align="center" bgcolor="#a9c7a9">Yes</td>
</tr>
</table>
<table border=0 align="right" cellpadding=0 cellspacing=0>
<tr>
<td valign="top" rowspan=5>Notes: </td>
<td>1. </td>
<td>Firebird omits all NULLs from SELECT DISTINCT and from UNION.</td>
</tr>
<tr><td>2. </td>
<td>Test data unavailable.</td>
</tr>
<tr><td>3. </td>
<td>The version of MySQL tested (3.23.41) does not support UNION.</td>
</tr>
<tr><td>4. </td>
<td>SQL Anywhere and Borland Interbase
do not allow NULLs in a UNIQUE column.</td>
</tr>
<tr><td>5. </td>
<td>Borland Interbase does not support CASE expressions.</td>
</tr>
</table>
<br clear="both">
<p> </p>
<p>
The following script was used to gather information for the table
above.
|