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Fixed bug#16861: User defined variable can have a wrong value if a tmp table was

used.

Sorting by RAND() uses a temporary table in order to get a correct results.
User defined variable was set during filling the temporary table and later
on it is substituted for its value from the temporary table. Due to this
it contains the last value stored in the temporary table.

Now if the result_field is set for the Item_func_set_user_var object it 
updates variable from the result_field value when being sent to a client.

The Item_func_set_user_var::check() now accepts a use_result_field
parameter. Depending on its value the result_field or the args[0] is used
to get current value.


mysql-test/r/user_var.result:
  Added a test case for bug#16861: User defined variable can have a wrong value if a tmp table was used.
mysql-test/t/user_var.test:
  Added a test case for bug#16861: User defined variable can have a wrong value if a tmp table was used.
sql/item_func.cc:
  Fixed bug#16861: User defined variable can have a wrong value if a tmp table was used.
  Now if the result_field is set for the Item_func_set_user_var object it 
  updates variable from the result_field value when being sent to a client.
  
  The Item_func_set_user_var::check() now accepts a use_result_field
  parameter. Depending on its value the result_field or the args[0] is used
  to get current value.
sql/item_func.h:
  Fixed bug#16861: User defined variable can have a wrong value if a tmp table was used.
  Added a new SUSERVAR_FUNC function type.
  Updated the Item_func_set_user_var::check() function declaration.
  Added the Item_func_set_user_var::send() member function.
sql/set_var.cc:
  Fixed bug#16861: User defined variable can have a wrong value if a tmp table was used.
  Modified to use updated Item_func_set_user_var::check() function.
sql/sql_class.cc:
  Fixed bug#16861: User defined variable can have a wrong value if a tmp table was used.
  Modified to use updated Item_func_set_user_var::check() function.
sql/sql_select.cc:
  Fixed bug#16861: User defined variable can have a wrong value if a tmp table was used.
  Now an Item_func_set_user_var object isn't substituted for an Item_field object after filling a temporary table.
This commit is contained in:
unknown
2006-08-22 17:37:41 +04:00
parent 6071b686b1
commit c623e54fb8
7 changed files with 58 additions and 17 deletions

View File

@ -292,3 +292,12 @@ SELECT @a;
@a
18446744071710965857
drop table bigfailure;
create table t1(f1 int, f2 int);
insert into t1 values (1,2),(2,3),(3,1);
select @var:=f2 from t1 group by f1 order by f2 desc limit 1;
@var:=f2
3
select @var;
@var
3
drop table t1;

View File

@ -202,3 +202,13 @@ SET @a := (select * from bigfailure where afield = (SELECT afield FROM bigfailur
SELECT @a;
drop table bigfailure;
#
# Bug#16861: User defined variable can have a wrong value if a tmp table was
# used.
#
create table t1(f1 int, f2 int);
insert into t1 values (1,2),(2,3),(3,1);
select @var:=f2 from t1 group by f1 order by f2 desc limit 1;
select @var;
drop table t1;