CAST関数は、あるデータ型の値を別のデータ型に変換するために使用されます。
CAST
記述
CAST ( 変換する値 AS 変換する型 )
mysql> SELECT CAST(123 AS DATE);
+-------------------+
| CAST(123 AS DATE) |
+-------------------+
| 2000-01-23 |
+-------------------+
1 row in set (0.00 sec)
mysql> SELECT CAST(123 AS TIME);
+-------------------+
| CAST(123 AS TIME) |
+-------------------+
| 00:01:23 |
+-------------------+
1 row in set (0.00 sec)
mysql> SELECT CAST(123 AS DATETIME);
+-----------------------+
| CAST(123 AS DATETIME) |
+-----------------------+
| 2000-01-23 00:00:00 |
+-----------------------+
1 row in set (0.00 sec)