>Description:
A column of the SELECT-part of a query returns allways NULL in some cases.
This seems to happen when using a "GROUP BY" and computing on some parts of the SELECT.
>How-To-Repeat:
create table users_table (id integer primary key not null auto_increment,
gender varchar(1));
insert into users_table values(NULL, 'M');
insert into users_table values(NULL, 'F');
insert into users_table values(NULL, 'F');
insert into users_table values(NULL, 'F');
insert into users_table values(NULL, 'M');
create table log_table (user_id integer not null, timestamp datetime);
insert into log_table values (1, SYSDATE());
insert into log_table values (2, SYSDATE());
insert into log_table values (1, SYSDATE());
insert into log_table values (3, SYSDATE());
insert into log_table values (4, SYSDATE());
insert into log_table values (4, SYSDATE());
SELECT u.gender AS gender, count(DISTINCT u.id) AS dist_count, (count(DISTINCT
u.id)/5*100) AS percentage FROM users_table u, log_table l WHERE l.user_id = u.id
GROUP BY u.gender ORDER BY percentage;
>Fix:
It seems to be a problem when inserting NULL values in the
auto_increment-column of table users_table. When inserting real values instead of
NULL-values everything works just fine.
Executing a slightly modified SELECT-statement solves the problem too:
SELECT concat(u.gender, '') AS gender, count(DISTINCT u.id) AS dist_count,
(count(DISTINCT u.id)/5*100) AS percentage FROM users_table u, log_table l WHERE
l.user_id = u.id GROUP BY u.gender ORDER BY percentage;
>Submitter-Id: <submitter ID>
>Originator: Niek Kerkemeijer
>Organization: Web Power BV
>MySQL support: none
>Synopsis: A column of the SELECT-part of a query returns allways NULL in some
>cases.
>Severity: non-critical
>Priority: medium
>Category: mysql
>Class: sw-bug
>Release: mysql-3.23.49a (Official MySQL RPM)
>Environment:
System: Linux hp.office.webpower.nl 2.2.16-22smp #1 SMP Tue Aug 22 16:39:21 EDT 2000
i686 unknown
Architecture: i686
Some paths: /usr/bin/perl /usr/bin/make /usr/bin/gmake /usr/bin/gcc /usr/bin/cc
GCC: Reading specs from /usr/lib/gcc-lib/i386-redhat-linux/2.96/specs
gcc version 2.96 20000731 (Red Hat Linux 7.0)
Compilation info: CC='gcc' CFLAGS='-O6 -fno-omit-frame-pointer -mpentium' CXX='gcc'
CXXFLAGS='-O6 -fno-omit-frame-pointer -felide-constructors
-fno-exceptions -fno-rtti -mpentium' LDFLAGS=''
LIBC:
lrwxrwxrwx 1 root root 14 Apr 2 2001 /lib/libc.so.6 ->
libc-2.1.92.so
-rwxr-xr-x 1 root root 4776568 Aug 30 2000 /lib/libc-2.1.92.so
-rw-r--r-- 1 root root 22607104 Aug 30 2000 /usr/lib/libc.a
-rw-r--r-- 1 root root 178 Aug 30 2000 /usr/lib/libc.so
Configure command: ./configure --disable-shared --with-mysqld-ldflags=-all-static
--with-client-ldflags=-all-static --with-other-libc=/usr/local/mysql-glibc
--without-berkeley-db --without-innodb --enable-assembler --enable-local-infile
--with-mysqld-user=mysql --with-unix-socket-path=/var/lib/mysql/mysql.sock --prefix=/
--with-extra-charsets=complex --exec-prefix=/usr --libexecdir=/usr/sbin
--sysconfdir=/etc --datadir=/usr/share --localstatedir=/var/lib/mysql
--infodir=/usr/info --includedir=/usr/include --mandir=/usr/man
'--with-comment=Official MySQL RPM' CC=gcc 'CFLAGS=-O6 -fno-omit-frame-pointer
-mpentium' 'CXXFLAGS=-O6 -fno-omit-frame-pointer -felide-constructors
-fno-exceptions -fno-rtti -mpentium' CXX=gcc
---------------------------------------------------------------------
Before posting, please check:
http://www.mysql.com/manual.php (the manual)
http://lists.mysql.com/ (the list archive)
To request this thread, e-mail <[EMAIL PROTECTED]>
To unsubscribe, e-mail <[EMAIL PROTECTED]>
Trouble unsubscribing? Try: http://lists.mysql.com/php/unsubscribe.php
