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Update the NULL-handling chart with new information about Firebird. (CVS 1072)

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FossilOrigin-Name: 17bdfeb284880d82cd546e6c191c3a37121ec861
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drh 2003-08-13 11:29:23 +00:00
parent 41a8230fef
commit b2446f9bbf
3 changed files with 37 additions and 12 deletions
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12
manifest
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@ -1,5 +1,5 @@
C Make\sthe\ssqliteOsCurrentTime()\sfunction\swork\sfor\sWindows.\s\sCode\scontributed\nby\s"e4liberty"\son\sthe\smailing\slist.\s(CVS\s1071)
D 2003-08-10T16:16:22
C Update\sthe\sNULL-handling\schart\swith\snew\sinformation\sabout\sFirebird.\s(CVS\s1072)
D 2003-08-13T11:29:24
F Makefile.in 9ad23ed4ca97f9670c4496432e3fbd4b3760ebde
F Makefile.linux-gcc b86a99c493a5bfb402d1d9178dcdc4bd4b32f906
F README f1de682fbbd94899d50aca13d387d1b3fd3be2dd
@ -160,7 +160,7 @@ F www/formatchng.tcl ca6cc1cb1bef9bc36f0619049d3c95e749bc6983
F www/index.tcl 64f867e40c1c4a8a0ffe560ec372df737ceeaec5
F www/lang.tcl 5f39bbda1ba38a28f18f97bd98c81f40355393b2
F www/mingw.tcl d96b451568c5d28545fefe0c80bee3431c73f69c
F www/nulls.tcl 4ac1c9bbb8a20a76500d18d63b383f51bb7d8be7
F www/nulls.tcl 9cb56d98c0c623074cda4360a415f3f0a7074c90
F www/omitted.tcl fe59eaa9c1459cbf08fa7daa83421bfc814331bb
F www/opcode.tcl b8d561f33597c62955796b797646f00144d97332
F www/quickstart.tcl 4e97bef825e6a4153c43afb9f97235fc4da278ab
@ -168,7 +168,7 @@ F www/speed.tcl 2f6b1155b99d39adb185f900456d1d592c4832b3
F www/sqlite.tcl 3c83b08cf9f18aa2d69453ff441a36c40e431604
F www/tclsqlite.tcl 1db15abeb446aad0caf0b95b8b9579720e4ea331
F www/vdbe.tcl 9b9095d4495f37697fd1935d10e14c6015e80aa1
P 94243edac14b90ef898093b85e1959c20fa23ae9
R d06ee94e7e293f14bb7a17592af45795
P 02fac304c9ec9012f3cc4f04d2c4cac5e37b0024
R c5c60d7816b69e7ad636fa582dc70cef
U drh
Z c133f327a7247010c46dbc5ed1b64175
Z 5cc44053e6e9f069f799212980612ed0

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02fac304c9ec9012f3cc4f04d2c4cac5e37b0024
17bdfeb284880d82cd546e6c191c3a37121ec861

35
www/nulls.tcl
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@ -1,7 +1,7 @@
#
# Run this script to generated a nulls.html output file
#
set rcsid {$Id: nulls.tcl,v 1.3 2003/07/07 00:10:40 drh Exp $}
set rcsid {$Id: nulls.tcl,v 1.4 2003/08/13 11:29:24 drh Exp $}
puts {<html>
<head>
@ -33,6 +33,7 @@ was to make SQLite work like all the other engines.
A SQL test script was developed and run by volunteers on various
SQL RDBMSes and the results of those tests were used to deduce
how each engine processed NULL values.
The original tests were run in May of 2002.
A copy of the test script is found at the end of this document.
</p>
@ -55,6 +56,29 @@ change the value of the NULL_ALWAYS_DISTINCT #define in the
<tt>sqliteInt.h</tt> source file and recompile.
</p>
<blockquote>
<p>
<i>Update 2003-07-13:</i>
Since this document was originally written some of the database engines
tested have been updated and users have been kind enough to send in
corrections to the chart below. The original data showed a wide variety
of behaviors, but over time the range of behaviors has converged toward
the PostgreSQL/Oracle model. The only significant difference
is that Informix and MS-SQL both threat NULLs as
indistinct in a UNIQUE column.
</p>
<p>
The fact that NULLs are distinct for UNIQUE columns but are indistinct for
SELECT DISTINCT and UNION continues to be puzzling. It seems that NULLs
should be either distinct everywhere or nowhere. And the SQL standards
documents suggest that NULLs should be distinct everywhere. Yet as of
this writing, no SQL engine tested treats NULLs as distinct in a SELECT
DISTINCT statement or in a UNION.
</p>
</blockquote>
<p>
The following table shows the results of the NULL handling experiments.
</p>
@ -172,19 +196,19 @@ The following table shows the results of the NULL handling experiments.
</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="#aaaad2">(Note 1)</td>
<td valign="center" align="center" bgcolor="#c7a9a9">No (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="#aaaad2">(Note 1)</td>
<td valign="center" align="center" bgcolor="#c7a9a9">No (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="#aaaad2">(Note 2)</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 5)</td>
</tr>
@ -206,7 +230,8 @@ The following table shows the results of the NULL handling experiments.
<tr>
<td valign="top" rowspan=5>Notes:&nbsp;&nbsp;</td>
<td>1.&nbsp;</td>
<td>Firebird omits all NULLs from SELECT DISTINCT and from UNION.</td>
<td>Older versions of firebird omits all NULLs from SELECT DISTINCT
and from UNION.</td>
</tr>
<tr><td>2.&nbsp;</td>
<td>Test data unavailable.</td>