在MySQL表中检查值是否存在于列中？

首先让我们创建一个表 –

mysql> create table DemoTable807(
    ClientId int NOT NULL AUTO_INCREMENT PRIMARY KEY,
    ClientName varchar(100),
    ClientCountryName varchar(100)
);
Query OK, 0 rows affected (0.64 sec)

使用insert命令在表中插入一些记录 –

mysql> insert into DemoTable807(ClientName,ClientCountryName) values('Chris','UK');
Query OK, 1 row affected (0.20 sec)
mysql> insert into DemoTable807(ClientName,ClientCountryName) values('David','AUS');
Query OK, 1 row affected (0.15 sec)
mysql> insert into DemoTable807(ClientName,ClientCountryName) values('Robert','US');
Query OK, 1 row affected (0.74 sec)
mysql> insert into DemoTable807(ClientName,ClientCountryName) values('Mike','ENG');
Query OK, 1 row affected (0.14 sec)

使用select语句从表中显示所有记录 –

mysql> select *from DemoTable807;

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)

以下是在MySQL表中检查值是否存在于列中的查询 –

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

将产生以下输出 –

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

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