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.
The bug caused wrong result sets for union constructs of the form
(SELECT ... ORDER BY order_list1 [LIMIT n]) ORDER BY order_list2.
For such queries order lists were concatenated and limit clause was
completely neglected.
The problem was that when a QUICK_SELECT access method is chosen,
test_if_skip_sort_order() discovered that the index being used
by the quick select will not deliver tuples in sorted order.
In this case test_if_skip_sort_order() tried to change the index
used by the quick select, but it didn't properly set the other
members of the quick select, and especially the range flags of
the ranges in QUICK_SELECT::ranges.
The fix re-invokes the function SQL_SELECT::test_quick_select
to correctly create a valid QUICK_SELECT object.
identical to another in result"
According to SQL standard queries like
"select t1.a as col from t1, t2 order by a" should return an error if
both tables contain field a.
When in find_item_in_list() we are looking for item we should take into account unaliased
names of the fields but only if item with such aliased name is not found.
Also we should ignore aliases when looking for fully specified field.
result of the test case for FORCE INDEX on ORDER BY
order_by.test:
test case for FORCE INDEX on ORDER BY
sql_select.cc:
Changing behaviour that MySQL server takes FORCE INDEX clause into account when optimising ORDER BY clause
Added ALL as parameter option for all group functions.
Make join handling uniform. This allows us to use ',', JOIN and INNER JOIN the same way.
Sort NULL last if DESC is used (ANSI SQL 99 requirement)
