MySQL CONCAT方法用法及代码示例

例子

考虑下表有关一些学生的信息：

可以使用此处的代码创建上述示例表

基本用法

要将 fname 和 lname 连接起来，中间有一个空格：

SELECT CONCAT(fname, ' ', lname)
FROM students;



+---------------------------+
| CONCAT(fname, ' ', lname) |
+--------------------------+
| Sky Towner                |
| Ben Davis                 |
| Travis Apple              |
| Arthur David              |
| Benjamin Town             |
+---------------------------+

要使用 AS 为结果列提供别名：

SELECT CONCAT(fname, ' ', lname) AS "Full Name"
FROM students;



+---------------+
| Full Name     |
+---------------+
| Sky Towner    |
| Ben Davis     |
| Travis Apple  |
| Arthur David  |
| Benjamin Town |
+---------------+

数值参数

数字参数自动转换为字符串：

SELECT CONCAT(fname, ' is ', age, ' years old.') AS "Sentence"
FROM students;



+---------------------------+
| Sentence                  |
+---------------------------+
| Sky is 17 years old.      |
| Ben is 19 years old.      |
| Travis is 18 years old.   |
| Arthur is 16 years old.   |
| Benjamin is 17 years old. |
+---------------------------+

空参数

如果任何参数是 NULL ，则返回 NULL ：

SELECT CONCAT('Hello', NULL);



+-----------------------+
| CONCAT('Hello', NULL) |
+-----------------------+
| NULL                  |
+-----------------------+