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检查值是否存在于MySQL表的列中？

2024-05-01 15:18:04 436

让我们首先创建一个表-

mysql> create table DemoTable807(
   ClientId int NOT NULL AUTO_INCREMENT PRIMARY KEY,
   ClientName varchar(100),
   ClientCountryName varchar(100)
);

使用插入命令在表中插入一些记录-

mysql> insert into DemoTable807(ClientName,ClientCountryName) values('Chris','UK');
mysql> insert into DemoTable807(ClientName,ClientCountryName) values('David','AUS');
mysql> insert into DemoTable807(ClientName,ClientCountryName) values('Robert','US');
mysql> insert into DemoTable807(ClientName,ClientCountryName) values('Mike','ENG');

使用select语句显示表中的所有记录-

mysql> select *from DemoTable807;

这将产生以下输出-

+----------+------------+-------------------+
| ClientId | ClientName | ClientCountryName |
+----------+------------+-------------------+
|        1 | Chris      | UK                |
|        2 | David      | AUS               |
|        3 | Robert     | US                |
|        4 | Mike       | ENG               |
+----------+------------+-------------------+
4 rows in set (0.00 sec)

以下是检查MySQL表的列中是否存在值的查询-

mysql> select *from DemoTable807 where ClientCountryName='US';

这将产生以下输出-

+----------+------------+-------------------+
| ClientId | ClientName | ClientCountryName |
+----------+------------+-------------------+
|        3 | Robert     | US                |
+----------+------------+-------------------+
1 row in set (0.00 sec)

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检查值是否存在于MySQL表的列中？

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