mysql兩列合成一列，mysql兩列一列

mysql兩列合成一列，mysql兩列一列

比如：有姓和名兩列，我想查詢的結果為一列。就需要concat關鍵字了。sql如下：

select concat(firstName,lastName) from tj_user

mysql 兩列合并 一列

使用下面的SQL語句，運行一次後就何必了，然後就可以刪除Adress2列：
update Adress set Adress1=concate(Adress1,Adress2)
 
mysql 中怎在兩列之間添加一列

mysql> CREATE TABLE TESTTABLE(
-> A INT DEFAULT 0,
-> B INT DEFAULT 0
-> )ENGINE=INNODB DEFAULT CHARSET=UTF8;
Query OK, 0 rows affected

mysql> DESC TESTTABLE;
+-------+---------+------+-----+---------+-------+
| Field | Type | Null | Key | Default | Extra |
+-------+---------+------+-----+---------+-------+
| A | int(11) | YES | | 0 | |
| B | int(11) | YES | | 0 | |
+-------+---------+------+-----+---------+-------+
2 rows in set

mysql> ALTER TABLE TESTTABLE ADD COLUMN C INT DEFAULT 0 AFTER A;
Query OK, 0 rows affected
Records: 0 Duplicates: 0 Warnings: 0
mysql> DESC TESTTABLE;
+-------+---------+------+-----+---------+-------+
| Field | Type | Null | Key | Default | Extra |
+-------+---------+------+-----+---------+-------+
| A | int(11) | YES | | 0 | |
| C | int(11) | YES | | 0 | |
| B | int(11) | YES | | 0 | |
+-------+---------+------+-----+---------+-------+
3 rows in set