* キャスト関数 [#zaee95ac]
** CAST()関数 [#c7d04efc]
SELECT CAST(1-2 AS UNSIGNED)
*** 参考 [#h7814779]
http://dev.mysql.com/doc/refman/5.1/ja/cast-functions.html
** DateTimeのキャスト [#sc590888]
キャストしても望んだ結果にならないので、DATE()関数を使う。
mysql> SELECT DATE '2010-01-01 10:00:00' = DATE '2010-01-01' AS ret;
+-----+
| ret |
+-----+
| 0 |
+-----+
mysql> SELECT DATE('2010-01-01 10:00:00') = DATE '2010-01-01' AS ret;
+------+
| ret |
+------+
| 1 |
+------+
*** 参考 [#a5803d68]
http://dev.mysql.com/doc/refman/5.1/ja/date-and-time-functions.html