mysql> select TRIM(' ');
+-------------+
| TRIM(' ') |
+-------------+
| |
+-------------+
1 row in set (0.00 sec)
现在 需要判断TRIM(' ')的值 请问这个该如何判断 而下面这个说明他不是空啊;
mysql> select 'null' from role where TRIM(' ') is null;
Empty set (0.00 sec)mysql> select 'null' from role where TRIM(' ') is not null;
+------+
| null |
+------+
| null |
| null |
+------+
2 rows in set (0.00 sec)
Empty set (0.00 sec)mysql> SELECT 'null' FROM t_control WHERE TRIM(TRIM(' ')) IS NOT NULL;
+------+
| null |
+------+
| null |
+------+
1 row in set (0.00 sec)
TRIM(' ')=''
mysql> select TRIM(' ')='';
+----------------+
| TRIM(' ')='' |
+----------------+
| 1 |
+----------------+
1 row in set (0.22 sec)mysql>