MySQL 如何使用查询连接来自不同列和附加字符串的字符串

让我们首先创建一个表 –

mysql> create table DemoTable
(
   FirstName varchar(100),
   LastName varchar(100)
);
Query OK, 0 rows affected (0.76 sec)

使用insert命令将一些记录插入表中 –

mysql> insert into DemoTable values('Chris','Brown');
Query OK, 1 row affected (0.12 sec)
mysql> insert into DemoTable values('Adam','Smith');
Query OK, 1 row affected (0.19 sec)
mysql> insert into DemoTable values('Carol','Taylor');
Query OK, 1 row affected (0.11 sec)
mysql> insert into DemoTable values('David','Miller');
Query OK, 1 row affected (0.12 sec)

使用select语句显示表中的所有记录 –

mysql> select * from DemoTable;

这将产生以下输出 –

+-----------+----------+
| FirstName | LastName |
+-----------+----------+
| Chris     | Brown    |
| Adam      | Smith    |
| Carol     | Taylor   |
| David     | Miller   |
+-----------+----------+
4 rows in set (0.00 sec)

以下是执行连接的查询。在这里，我们有FirstName和LastName。除此之外，还为所有字符串值在开头连接了一个附加字符串 –

mysql> select concat('Hello ',FirstName,' ',LastName) from DemoTable;

这将产生以下输出 –

+-----------------------------------------+
| concat('Hello ',FirstName,' ',LastName) |
+-----------------------------------------+
| Hello Chris Brown                       |
| Hello Adam Smith                        |
| Hello Carol Taylor                      |
| Hello David Miller                      |
+-----------------------------------------+
4 rows in set (0.00 sec)