MySQL 如何连接所有列

首先，您需要知道表中存在多少列。以下是了解列名的语法 −

show columns from yourTableName;

以下是连接所有列的语法 −

select concat(yourColumnName1,yourColumnName2,yourColumnName3,........N) from yourTableName;

让我们首先创建一个表 −

mysql> create table DemoTable
   (
   CustomerId int,
   CustomerName varchar(20),
   CustomerAge int
   );
Query OK, 0 rows affected (0.66 sec)

以下是获取精确列的查询 −

mysql> show columns from DemoTable;

这将产生以下输出 −

+--------------+-------------+------+-----+---------+-------+
| Field        | Type        | Null | Key | Default | Extra |
+--------------+-------------+------+-----+---------+-------+
| CustomerId   | int(11)     | YES  |     | NULL    |       |
| CustomerName | varchar(20) | YES  |     | NULL    |       |
| CustomerAge  | int(11)     | YES  |     | NULL    |       |
+--------------+-------------+------+-----+---------+-------+
3 rows in set (0.00 sec)

使用插入命令在表中插入记录−

mysql> insert into DemoTable values(101,'Chris',26);
Query OK, 1 row affected (0.15 sec)
mysql> insert into DemoTable values(102,'Robert',27);
Query OK, 1 row affected (0.16 sec)

使用select语句从表中显示所有记录−

mysql> select * from DemoTable;

这将产生以下输出 −

+------------+--------------+-------------+
| CustomerId | CustomerName | CustomerAge |
+------------+--------------+-------------+
| 101        | Chris        | 26          |
| 102        | Robert       | 27          |
+------------+--------------+-------------+
2 rows in set (0.00 sec)

以下是连接所有列的查询 −

mysql> select concat(CustomerId,CustomerName,CustomerAge) from DemoTable;

这将产生以下输出 −

+---------------------------------------------+
| concat(CustomerId,CustomerName,CustomerAge) |
+---------------------------------------------+
| 101Chris26                                  |
| 102Robert27                                 |
+---------------------------------------------+
2 rows in set (0.00 sec)

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