mysql locate()函数

mysql> select * from test;
+----+------------+-------+-----------+
| id | name       | score | subject   |
+----+------------+-------+-----------+
|   | xiaoming   |     | shuxue    |
|   | xiaohong   |     | shuxue    |
|   | xiaohong   |     | english   |
|   | xiaohong   |     | physics   |
|   | xiaohong   |     | astronaut |
|   | xiaoming   |     | physics   |
|   | xiaoming   |     | astronaut |
|   | xiaoming   |     | english   |
|   | xiaobai    |     | astronaut |
|  | .2xiaobai |     | english   |
|  | .2xiaobai |     | physics   |
|  | 3xiaobai   |     | shuxue    |
|  | 123xiaohei |     | astronaut |
|  | xiaohei    |     | shuxue    |
|  | xiaohei    |     | physics   |
|  | .12xiaohei |     | english   |
+----+------------+-------+-----------+
 rows in set (0.00 sec)
 
mysql> select locate("xiao",name) from test where id=;
+---------------------+
| locate("xiao",name) |
+---------------------+
|                    |
+---------------------+
 row in set (0.00 sec)
 
mysql> select locate("iao",name) from test where id=;
+--------------------+
| locate("iao",name) |
+--------------------+
|                   |
+--------------------+
 row in set (0.00 sec)
 
mysql> select locate("o",name) from test where id=;
+------------------+
| locate("o",name) |
+------------------+
|                 |
+------------------+
 row in set (0.00 sec)
 
mysql> select locate("o",name,) from test where id=;
+--------------------+
| locate("o",name,) |
+--------------------+
|                   |
+--------------------+
 row in set (0.00 sec)