MySQL 在Select中显示列的值两次

您可以使用concat()函数。首先让我们创建一个表 −

mysql> create table DemoTable
(
   Value int
);
Query OK, 0 rows affected (0.73 sec)

使用insert命令将一些记录插入表中 −

mysql> insert into DemoTable values(100);
Query OK, 1 row affected (0.18 sec)
mysql> insert into DemoTable values(200);
Query OK, 1 row affected (0.08 sec)
mysql> insert into DemoTable values(100);
Query OK, 1 row affected (0.11 sec)
mysql> insert into DemoTable values(200);
Query OK, 1 row affected (0.10 sec)
mysql> insert into DemoTable values(200);
Query OK, 1 row affected (0.11 sec)
mysql> insert into DemoTable values(100);
Query OK, 1 row affected (0.30 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 −

+-------+
| Value |
+-------+
|   100 |
|   200 |
|   100 |
|   200 |
|   200 |
|   100 |
+-------+
6 rows in set (0.00 sec)

下面是显示MySQL中列值两次的查询语句 −

mysql> select concat(Value,'~',Value) from DemoTable group by Value;

这将产生以下输出 −

+-------------------------+
| concat(Value,'~',Value) |
+-------------------------+
|                 100~100 |
|                 200~200 |
+-------------------------+
2 rows in set (0.00 sec)

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