Bug#59173: Failure to handle DATE(TIME) values where Year, Month or Day is

ZERO
      
When dates are represented internally as strings, i.e. when a string constant
is compared to a date value, both values are converted to long integers,
ostensibly for fast comparisons. DATE typed integer values are converted to
DATETIME by multiplying by 1,000,000 (each digit pair representing hour,
minute and second, respectively). But the mechanism did not distuinguish
cached INTEGER values, already in correct format, from newly converted
strings.

Fixed by marking the INTEGER cache as being of DATETIME format.

mysql-test/r/type_datetime.result

@@ -637,4 +637,15 @@ CAST(CAST('2008-07-29T10:42:51.1234567' AS DateTime) AS DECIMAL(30,7))
 20080729104251.1234560
 Warnings:
 Warning	1292	Truncated incorrect datetime value: '2008-07-29T10:42:51.1234567'
+# 
+# Bug#59173: Failure to handle DATE(TIME) values where Year, Month or
+# Day is ZERO 
+# 
+CREATE TABLE t1 (dt1 DATETIME);
+INSERT INTO t1 (dt1) VALUES ('0000-00-01 00:00:01');
+DELETE   FROM t1 WHERE dt1 = '0000-00-01 00:00:01';
+# Should be empty
+SELECT * FROM t1;
+dt1
+DROP TABLE t1;
 End of 5.1 tests

mysql-test/t/type_datetime.test

@@ -445,4 +445,15 @@ SELECT CAST(CAST('00000002006-000008-0000010 000010:0000011:00000012.012345'  AS
 # show we truncate microseconds from the right
 SELECT CAST(CAST('2008-07-29T10:42:51.1234567' AS DateTime) AS DECIMAL(30,7));
 
+--echo # 
+--echo # Bug#59173: Failure to handle DATE(TIME) values where Year, Month or
+--echo # Day is ZERO 
+--echo # 
+CREATE TABLE t1 (dt1 DATETIME);
+INSERT INTO t1 (dt1) VALUES ('0000-00-01 00:00:01');
+DELETE   FROM t1 WHERE dt1 = '0000-00-01 00:00:01';
+--echo # Should be empty
+SELECT * FROM t1;
+DROP TABLE t1;
+
 --echo End of 5.1 tests

sql/item_cmpfunc.cc

@@ -913,7 +913,7 @@ int Arg_comparator::set_cmp_func(Item_result_field *owner_arg,
         cache_converted_constant can't be used here because it can't
         correctly convert a DATETIME value from string to int representation.
       */
-      Item_cache_int *cache= new Item_cache_int();
+      Item_cache_int *cache= new Item_cache_int(MYSQL_TYPE_DATETIME);
       /* Mark the cache as non-const to prevent re-caching. */
       cache->set_used_tables(1);
       if (!(*a)->is_datetime())