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fixed subselect explain bug

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This commit is contained in:
bell@sanja.is.com.ua
2002-11-17 22:23:57 +02:00
parent 08e6939254
commit c0764205cf
3 changed files with 36 additions and 8 deletions
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18
mysql-test/r/subselect.result
View File

@ -269,3 +269,21 @@ INSERT INTO iftest VALUES ();
SELECT field FROM iftest WHERE 1=(SELECT 1 UNION ALL SELECT 1 FROM (SELECT 1) HAVING field='b');
Subselect returns more than 1 record
drop table iftest;
drop table if exists threadhardwarefr7;
CREATE TABLE `threadhardwarefr7` (
`numeropost` mediumint(8) unsigned NOT NULL default '0',
`numreponse` int(10) unsigned NOT NULL auto_increment,
`pseudo` varchar(35) NOT NULL default '',
PRIMARY KEY (`numeropost`,`numreponse`),
UNIQUE KEY `numreponse` (`numreponse`),
KEY `pseudo` (`pseudo`,`numeropost`)
) TYPE=MyISAM;
INSERT INTO threadhardwarefr7 (numeropost,numreponse,pseudo) VALUES (1,1,'joce'),(1,2,'joce'),(1,3,'test');
EXPLAIN SELECT MAX(numreponse) FROM threadhardwarefr7 WHERE numeropost='1';
id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE Select tables optimized away
EXPLAIN SELECT numreponse FROM threadhardwarefr7 WHERE numeropost='1' AND numreponse=(SELECT MAX(numreponse) FROM threadhardwarefr7 WHERE numeropost='1');
id select_type table type possible_keys key key_len ref rows Extra
1 PRIMARY threadhardwarefr7 const PRIMARY,numreponse PRIMARY 7 const,const 1
2 SUBSELECT Select tables optimized away
drop table if exists threadhardwarefrtest7;

15
mysql-test/t/subselect.test
View File

@ -166,3 +166,18 @@ INSERT INTO iftest VALUES ();
-- error 1240
SELECT field FROM iftest WHERE 1=(SELECT 1 UNION ALL SELECT 1 FROM (SELECT 1) HAVING field='b');
drop table iftest;
drop table if exists threadhardwarefr7;
CREATE TABLE `threadhardwarefr7` (
`numeropost` mediumint(8) unsigned NOT NULL default '0',
`numreponse` int(10) unsigned NOT NULL auto_increment,
`pseudo` varchar(35) NOT NULL default '',
PRIMARY KEY (`numeropost`,`numreponse`),
UNIQUE KEY `numreponse` (`numreponse`),
KEY `pseudo` (`pseudo`,`numeropost`)
) TYPE=MyISAM;
INSERT INTO threadhardwarefr7 (numeropost,numreponse,pseudo) VALUES (1,1,'joce'),(1,2,'joce'),(1,3,'test');
EXPLAIN SELECT MAX(numreponse) FROM threadhardwarefr7 WHERE numeropost='1';
EXPLAIN SELECT numreponse FROM threadhardwarefr7 WHERE numeropost='1' AND numreponse=(SELECT MAX(numreponse) FROM threadhardwarefr7 WHERE numeropost='1');
drop table if exists threadhardwarefrtest7;

11
sql/sql_select.cc
View File

@ -395,13 +395,7 @@ JOIN::optimize()
zero_result_cause= "No matching min/max row";
DBUG_RETURN(0);
}
if (select_options & SELECT_DESCRIBE)
{
select_describe(this, false, false, false,
"Select tables optimized away");
delete procedure;
DBUG_RETURN(1);
}
zero_result_cause= "Select tables optimized away";
tables_list= 0; // All tables resolved
}
}
@ -663,7 +657,8 @@ JOIN::exec()
{ // Only test of functions
error=0;
if (select_options & SELECT_DESCRIBE)
select_describe(this, false, false, false, "No tables used");
select_describe(this, false, false, false,
(zero_result_cause?zero_result_cause:"No tables used"));
else
{
result->send_fields(fields_list,1);