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Bug #22457: Column alias in ORDER BY works, but not if in an expression

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The parser is allocating Item_field for references by name in ORDER BY
 expressions. Such expressions however may point not only to Item_field 
 in the select list (or to a table column) but also to an arbitrary Item. 
 This causes Item_field::fix_fields to throw an error about missing 
 column.
 The fix substitutes Item_field for the reference with an Item_ref when 
 not pointing to Item_field.
This commit is contained in:
gkodinov/kgeorge@macbook.gmz 2006-11-03 18:48:16 +02:00
parent e1a7fb7b2c
commit 77acba320d
3 changed files with 73 additions and 3 deletions
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27
mysql-test/r/order_by.result
View File

@ -820,3 +820,30 @@ b a
20 1
10 2
DROP TABLE t1;
CREATE TABLE t1 (a INT);
INSERT INTO t1 VALUES (1),(2);
SELECT a + 1 AS num FROM t1 ORDER BY 30 - num;
num
3
2
SELECT CONCAT('test', a) AS str FROM t1 ORDER BY UPPER(str);
str
test1
test2
SELECT a + 1 AS num FROM t1 GROUP BY 30 - num;
num
3
2
SELECT a + 1 AS num FROM t1 HAVING 30 - num;
num
2
3
SELECT a + 1 AS num, num + 1 FROM t1;
ERROR 42S22: Unknown column 'num' in 'field list'
SELECT a + 1 AS num, (select num + 2 FROM t1 LIMIT 1) FROM t1;
num (select num + 2 FROM t1 LIMIT 1)
2 4
3 5
SELECT a.a + 1 AS num FROM t1 a JOIN t1 b ON num = b.a;
ERROR 42S22: Unknown column 'num' in 'on clause'
DROP TABLE t1;

16
mysql-test/t/order_by.test
View File

@ -559,4 +559,20 @@ INSERT INTO t1 VALUES (1,30), (2,20), (1,10), (2,30), (1,20), (2,10);
DROP TABLE t1;
#
# Bug #22457: Column alias in ORDER BY works, but not if in an expression
#
CREATE TABLE t1 (a INT); INSERT INTO t1 VALUES (1),(2);
SELECT a + 1 AS num FROM t1 ORDER BY 30 - num;
SELECT CONCAT('test', a) AS str FROM t1 ORDER BY UPPER(str);
SELECT a + 1 AS num FROM t1 GROUP BY 30 - num;
SELECT a + 1 AS num FROM t1 HAVING 30 - num;
--error 1054
SELECT a + 1 AS num, num + 1 FROM t1;
SELECT a + 1 AS num, (select num + 2 FROM t1 LIMIT 1) FROM t1;
--error 1054
SELECT a.a + 1 AS num FROM t1 a JOIN t1 b ON num = b.a;
DROP TABLE t1;
# End of 4.1 tests

33
sql/item.cc
View File

@ -1761,10 +1761,37 @@ bool Item_field::fix_fields(THD *thd, TABLE_LIST *tables, Item **ref)
Item** res= find_item_in_list(this, thd->lex->current_select->item_list,
&counter, REPORT_EXCEPT_NOT_FOUND,
&not_used);
if (res != (Item **)not_found_item && (*res)->type() == Item::FIELD_ITEM)
if (res != (Item **)not_found_item)
{
set_field((*((Item_field**)res))->field);
return 0;
if ((*res)->type() == Item::FIELD_ITEM)
{
/*
It's an Item_field referencing another Item_field in the select
list.
use the field from the Item_field in the select list and leave
the Item_field instance in place.
*/
set_field((*((Item_field**)res))->field);
return 0;
}
else
{
/*
It's not an Item_field in the select list so we must make a new
Item_ref to point to the Item in the select list and replace the
Item_field created by the parser with the new Item_ref.
*/
Item_ref *rf= new Item_ref(db_name,table_name,field_name);
if (!rf)
return 1;
thd->change_item_tree(ref, rf);
/*
Because Item_ref never substitutes itself with other items
in Item_ref::fix_fields(), we can safely use the original
pointer to it even after fix_fields()
*/
return rf->fix_fields(thd, tables, ref) || rf->check_cols(1);
}
}
}