diff options
Diffstat (limited to 'sql/item_func.h')
| -rw-r--r-- | sql/item_func.h | 29 |
1 files changed, 28 insertions, 1 deletions
diff --git a/sql/item_func.h b/sql/item_func.h index a367a0d74c4..3fc2586729d 100644 --- a/sql/item_func.h +++ b/sql/item_func.h @@ -1434,6 +1434,8 @@ class Item_func_min_max :public Item_hybrid_func { String tmp_value; int cmp_sign; +protected: + bool fix_attributes(Item **item, uint nitems); public: Item_func_min_max(THD *thd, List<Item> &list, int cmp_sign_arg): Item_hybrid_func(thd, list), cmp_sign(cmp_sign_arg) @@ -1474,7 +1476,32 @@ public: return Item_func_min_max::type_handler()-> Item_func_min_max_get_date(this, res, fuzzy_date); } - void fix_length_and_dec(); + void aggregate_attributes_real(Item **items, uint nitems) + { + /* + Aggregating attributes for the double data type for LEAST/GREATEST + is almost the same with aggregating for CASE-alike hybrid functions, + (CASE..THEN, COALESCE, IF, etc). + There is one notable difference though, when a numeric argument is mixed + with a string argument: + - CASE-alike functions return a string data type in such cases + COALESCE(10,'x') -> VARCHAR(2) = '10' + - LEAST/GREATEST returns double: + GREATEST(10,'10e4') -> DOUBLE = 100000 + As the string argument can represent a number in the scientific notation, + like in the example above, max_length of the result can be longer than + max_length of the arguments. To handle this properly, max_length is + additionally assigned to the result of float_length(decimals). + */ + Item_func::aggregate_attributes_real(items, nitems); + max_length= float_length(decimals); + } + void fix_length_and_dec() + { + if (aggregate_for_min_max(func_name(), args, arg_count)) + return; + fix_attributes(args, arg_count); + } }; class Item_func_min :public Item_func_min_max |