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法律研究在 MySQL 中连接字符串到 SELECT *?
使用 MySQL 中的 CONCAT() 函数连接字符串，如下面的语法所示
SELECT CONCAT(yourColumnName1,’anyConcatenationString’),CONCAT(yourColumnName2,’anyC oncatenationString’),....N from yourTableName;
为了理解上述语法，我们首先创建一个表。创建表的查询如下
mysql> create table selectConcat -> ( -> StudentId int, -> StudentName varchar(100), -> StudentAge int -> ); Query OK, 0 rows affected (1.32 sec)
使用插入命令在表中插入一些记录。查询如下
mysql> insert into selectConcat values(1,'Carol',23); Query OK, 1 row affected (0.19 sec) mysql> insert into selectConcat values(2,'John',24); Query OK, 1 row affected (0.25 sec) mysql> insert into selectConcat values(3,'Adam',25); Query OK, 1 row affected (0.14 sec) mysql> insert into selectConcat values(4,'Bob',21); Query OK, 1 row affected (0.20 sec) mysql> insert into selectConcat values(5,'Sam',22); Query OK, 1 row affected (0.16 sec)
使用 select 语句显示表中的所有记录。查询如下
mysql> select *from selectConcat;
以下是输出
+-----------+-------------+------------+ | StudentId | StudentName | StudentAge | +-----------+-------------+------------+ | 1 | Carol | 23 | | 2 | John | 24 | | 3 | Adam | 25 | | 4 | Bob | 21 | | 5 | Sam | 22 | +-----------+-------------+------------+ 5 rows in set (0.00 sec)
连接 select 语句中的字段。查询如下
mysql> select concat(StudentId,' as an Id'),concat(StudentName,' as a Name') from selectConcat;
以下是输出
+-------------------------------+----------------------------------+ | concat(StudentId,' as an Id') | concat(StudentName,' as a Name') | +-------------------------------+----------------------------------+ | 1 as an Id | Carol as a Name | | 2 as an Id | John as a Name | | 3 as an Id | Adam as a Name | | 4 as an Id | Bob as a Name | | 5 as an Id | Sam as a Name | +-------------------------------+----------------------------------+ 5 rows in set (0.00 sec)
更新日期：29-Jun-2020
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