'+' 拼接字符串引起的小事故

一、拼接字符串

    需求：account_code原来数据的基础上在其前添加‘HSJS’的标识……

    1）误操作一：

mysql> update  tbpayment_settlement  set  account_code = ('HSJS'+ account_code) where  id = 616783;
1292 - Truncated incorrect DOUBLE value: 'HSJS'
mysql> 

   2）误操作二：

mysql> update  tbpayment_settlement  set  account_code = ('1001'+ account_code) where  id = 616783;
1292 - Truncated incorrect DOUBLE value: '201908'
mysql> 

     补充：

mysql> select  account_code from  tbpayment_settlement  where id = 616783;
+--------------+
| account_code |
+--------------+
| 201908       |
+--------------+
1 row in set

mysql> 

解答：account_code为varchar类型，不能采用 ‘+’ 来拼接字符串，‘+’ 用于数字类型的相加。而字符串应使用concat(str1,str2,...)函数。

   3）正解

mysql> update  tbpayment_settlement  set  account_code = concat('HSJS',account_code) where  id = 616783;
Query OK, 1 row affected
Rows matched: 1  Changed: 1  Warnings: 0

mysql> select  account_code from  tbpayment_settlement  where id = 616783;
+----------------+
| account_code   |
+----------------+
| HSJS201908     |
+----------------+
1 row in set

mysql>