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Fixed bug in HAVING when refering to RAND() through alias

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(BUG 8216)
This commit is contained in:
monty@mysql.com
2005-02-07 18:13:57 +02:00
parent e7450d9781
commit 32f91f48e8
8 changed files with 126 additions and 29 deletions
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46
sql/item_cmpfunc.cc
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@@ -1960,6 +1960,36 @@ bool Item_cond::walk(Item_processor processor, byte *arg)
return Item_func::walk(processor, arg);
}
/*
Move SUM items out from item tree and replace with reference
SYNOPSIS
split_sum_func()
thd Thread handler
ref_pointer_array Pointer to array of reference fields
fields All fields in select
NOTES
This function is run on all expression (SELECT list, WHERE, HAVING etc)
that have or refer (HAVING) to a SUM expression.
The split is done to get an unique item for each SUM function
so that we can easily find and calculate them.
(Calculation done by update_sum_func() and copy_sum_funcs() in
sql_select.cc)
All found SUM items are added FIRST in the fields list and
we replace the item with a reference.
We also replace all functions without side effects (like RAND() or UDF's)
that uses columns as arguments.
For functions with side effects, we just remember any fields referred
by the function to ensure that we get a copy of the field value for the
first accepted row. This ensures that we can do things like
SELECT a*SUM(b) FROM t1 WHERE a=1
*/
void Item_cond::split_sum_func(THD *thd, Item **ref_pointer_array,
List<Item> &fields)
{
@@ -1969,10 +1999,22 @@ void Item_cond::split_sum_func(THD *thd, Item **ref_pointer_array,
const_item_cache=0;
while ((item=li++))
{
if (item->with_sum_func && item->type() != SUM_FUNC_ITEM)
/* with_sum_func is set for items that contains a SUM expression */
if (item->type() != SUM_FUNC_ITEM &&
(item->with_sum_func ||
(item->used_tables() & PSEUDO_TABLE_BITS)))
item->split_sum_func(thd, ref_pointer_array, fields);
else if (item->used_tables() || item->type() == SUM_FUNC_ITEM)
else if (item->type() == SUM_FUNC_ITEM ||
(item->used_tables() && item->type() != REF_ITEM))
{
/*
Replace item with a reference so that we can easily calculate
it (in case of sum functions) or copy it (in case of fields)
The test above is to ensure we don't do a reference for things
that are constants or are not yet calculated as in:
SELECT RAND() as r1, SUM(a) as r2 FROM t1 HAVING r1 > 1 AND r2 > 0
*/
Item **ref= li.ref();
uint el= fields.elements;
ref_pointer_array[el]= item;