Bug#31384 DATE_ADD() and DATE_SUB() return binary data

Problem: DATE_ADD() is a hybrid function and can return
DATE, DATETIME or VARCHAR data type depending on arguments.

In case of VARCHAR data type, DATE_ADD() reported "binary" character set,
which was wrong.

Fix: make DATE_ADD() return @character_set_connection in VARCHAR context.
 @ mysql-test/include/ctype_numconv.inc
   Adding tests
 @ mysql-test/r/ctype_binary.result
   Adding tests
 @ mysql-test/r/ctype_cp1251.result
   Adding tests
 @ mysql-test/r/ctype_latin1.result
   Adding tests
 @ mysql-test/r/ctype_ucs.result
   Adding tests
 @ mysql-test/r/ctype_utf8.result
   Adding tests
 @ sql/item_strfunc.cc
  - Moving code from Item_str_ascii_func::val_str() to
  Item_str_func::val_str_from_val_str_ascii(), as
  this code needs to be shared by Item_date_add_interval.
  - Adding str2 parameter to be used as a buffer, instead of
   using private ascii_buf member.
 @ sql/item_strfunc.h
  - Moving code from Item_str_ascii_func::val_str() to
  Item_str_func::val_str_from_val_str_ascii()
  - Removing "String *val_str_convert_from_ascii(String *str, String *ascii_buf)"
    prototype as it was neither used nor declared.
 @ sql/item_timefunc.h
  - Overwriting parent's charset_for_protocol() method,
    becase we need to behave differenlty in VARCHAR and DATE/DATETYPE context.
  - Adding ascii_buf for conversion.
  - Adding val_str_ascii() prototype.
  - Adding val_str() which uses newly added
    Item_str_func::val_str_from_val_str_ascii(),
    passing ascii_buf as a conversion buffer.

1 files changed, 40 insertions, 0 deletions

diff --git a/mysql-test/r/ctype_binary.result b/mysql-test/r/ctype_binary.result
index 4d526a86ade..58cd4b3524b 100644
--- a/mysql-test/r/ctype_binary.result
+++ b/mysql-test/r/ctype_binary.result
@@ -2767,6 +2767,46 @@ id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
 1	SIMPLE	t1	range	date_column	date_column	9	NULL	1	Using where
 DROP TABLE t1;
 #
+# Bug #31384 	DATE_ADD() and DATE_SUB() return binary data
+#
+SELECT @@collation_connection, @@character_set_results;
+@@collation_connection	@@character_set_results
+binary	binary
+CREATE TABLE t1 AS
+SELECT
+DATE_SUB('2007-08-03', INTERVAL 1 MINUTE) AS field_str1,
+DATE_SUB('2007-08-03 17:33:00', INTERVAL 1 MINUTE) AS field1_str2,
+DATE_SUB(DATE('2007-08-03'), INTERVAL 1 DAY) AS field_date,
+DATE_SUB(CAST('2007-08-03 17:33:00' AS DATETIME), INTERVAL 1 MINUTE) AS field_datetime;
+SHOW CREATE TABLE t1;
+Table	Create Table
+t1	CREATE TABLE `t1` (
+  `field_str1` varbinary(29) DEFAULT NULL,
+  `field1_str2` varbinary(29) DEFAULT NULL,
+  `field_date` date DEFAULT NULL,
+  `field_datetime` datetime DEFAULT NULL
+) ENGINE=MyISAM DEFAULT CHARSET=latin1
+DROP TABLE t1;
+SELECT
+DATE_SUB('2007-08-03', INTERVAL 1 DAY) AS field_str1,
+DATE_SUB('2007-08-03 17:33:00', INTERVAL 1 MINUTE) AS field1_str2,
+DATE_SUB(DATE('2007-08-03'), INTERVAL 1 DAY) AS field_date,
+DATE_SUB(CAST('2007-08-03 17:33:00' AS DATETIME), INTERVAL 1 MINUTE) AS field_datetime;
+Catalog	Database	Table	Table_alias	Column	Column_alias	Type	Length	Max length	Is_null	Flags	Decimals	Charsetnr
+def					field_str1	254	29	10	Y	128	31	63
+def					field1_str2	254	29	19	Y	128	31	63
+def					field_date	10	29	10	Y	128	31	63
+def					field_datetime	12	29	19	Y	128	31	63
+field_str1	field1_str2	field_date	field_datetime
+2007-08-02	2007-08-03 17:32:00	2007-08-02	2007-08-03 17:32:00
+SELECT
+HEX(DATE_SUB('2007-08-03', INTERVAL 1 MINUTE)) AS field_str1,
+HEX(DATE_SUB('2007-08-03 17:33:00', INTERVAL 1 MINUTE)) AS field1_str2,
+HEX(DATE_SUB(DATE('2007-08-03'), INTERVAL 1 DAY)) AS field_date,
+HEX(DATE_SUB(CAST('2007-08-03 17:33:00' AS DATETIME), INTERVAL 1 MINUTE)) AS field_datetime;
+field_str1	field1_str2	field_date	field_datetime
+323030372D30382D30322032333A35393A3030	323030372D30382D30332031373A33323A3030	323030372D30382D3032	323030372D30382D30332031373A33323A3030
+#
 # Bug#52159 returning time type from function and empty left join causes debug assertion
 #
 CREATE FUNCTION f1() RETURNS TIME RETURN 1;