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Fixed bug #21231: wrong results for a simple query with a

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a non-correlated single-row subquery over information schema.

The function get_all_tables filling all information schema
tables reset lex->sql_command to SQLCOM_SHOW_FIELDS. After
this the function could evaluate partial conditions related to
some columns. If these conditions contained a subquery over
information schema it led to a wrong evaluation and a wrong 
result set.
This bug was already fixed in 5.1.
This patch follows the way how it was done in 5.1 where
the value of lex->sql_command is set to SQLCOM_SHOW_FIELDS
in get_all_tables only for the calls of the function 
open_normal_and_derived_tables and is restored after these
calls.
This commit is contained in:
igor@olga.mysql.com 2006-07-24 19:05:46 -07:00
parent 74438f31e4
commit 69856b29b2
3 changed files with 28 additions and 6 deletions
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8
mysql-test/r/information_schema.result
View file

@ -1232,3 +1232,11 @@ TABLE_PRIVILEGES TABLE_SCHEMA
TRIGGERS TRIGGER_SCHEMA
USER_PRIVILEGES GRANTEE
VIEWS TABLE_SCHEMA
SELECT MAX(table_name) FROM information_schema.tables;
MAX(table_name)
VIEWS
SELECT table_name from information_schema.tables
WHERE table_name=(SELECT MAX(table_name)
FROM information_schema.tables);
table_name
VIEWS

10
mysql-test/t/information_schema.test
View file

@ -920,4 +920,14 @@ SELECT t.table_name, c1.column_name
c2.column_name LIKE '%SCHEMA%'
);
#
# Bug#21231: query with a simple non-correlated subquery over
# INFORMARTION_SCHEMA.TABLES
#
SELECT MAX(table_name) FROM information_schema.tables;
SELECT table_name from information_schema.tables
WHERE table_name=(SELECT MAX(table_name)
FROM information_schema.tables);
# End of 5.0 tests.

16
sql/sql_show.cc
View file

@ -2116,12 +2116,6 @@ int get_all_tables(THD *thd, TABLE_LIST *tables, COND *cond)
LINT_INIT(end);
LINT_INIT(len);
/*
Let us set fake sql_command so views won't try to merge
themselves into main statement.
*/
lex->sql_command= SQLCOM_SHOW_FIELDS;
lex->reset_n_backup_query_tables_list(&query_tables_list_backup);
/*
@ -2144,8 +2138,16 @@ int get_all_tables(THD *thd, TABLE_LIST *tables, COND *cond)
I_S tables will be done.
*/
thd->temporary_tables= open_tables_state_backup.temporary_tables;
/*
Let us set fake sql_command so views won't try to merge
themselves into main statement. If we don't do this,
SELECT * from information_schema.xxxx will cause problems.
SQLCOM_SHOW_FIELDS is used because it satisfies 'only_view_structure()'
*/
lex->sql_command= SQLCOM_SHOW_FIELDS;
res= open_normal_and_derived_tables(thd, show_table_list,
MYSQL_LOCK_IGNORE_FLUSH);
lex->sql_command= save_sql_command;
/*
get_all_tables() returns 1 on failure and 0 on success thus
return only these and not the result code of ::process_table()
@ -2267,8 +2269,10 @@ int get_all_tables(THD *thd, TABLE_LIST *tables, COND *cond)
TABLE_LIST *show_table_list= (TABLE_LIST*) sel.table_list.first;
lex->all_selects_list= &sel;
lex->derived_tables= 0;
lex->sql_command= SQLCOM_SHOW_FIELDS;
res= open_normal_and_derived_tables(thd, show_table_list,
MYSQL_LOCK_IGNORE_FLUSH);
lex->sql_command= save_sql_command;
/*
We should use show_table_list->alias instead of
show_table_list->table_name because table_name