它对您来说只是空白,因为您尚未设置sql_mode。如果您进行设置,则该查询将向您显示详细信息:
MysqL> SELECT @@sql_mode;
+------------+
| @@sql_mode |
+------------+
| |
+------------+
1 row in set (0.00 sec)
MysqL> set sql_mode=ORACLE;
Query OK, 0 rows affected (0.00 sec)
MysqL> SELECT @@sql_mode;
+----------------------------------------------------------------------------------------------------------------------+
| @@sql_mode |
+----------------------------------------------------------------------------------------------------------------------+
| PIPES_AS_CONCAT,ANSI_QUOTES,IGNORE_SPACE,ORACLE,NO_KEY_OPTIONS,NO_TABLE_OPTIONS,NO_FIELD_OPTIONS,NO_AUTO_CREATE_USER |
+----------------------------------------------------------------------------------------------------------------------+
1 row in set (0.00 sec)