如何在MySQL中处理多个AND条件？

要在MySQL中使用多个AND条件，以下是语法-

select *from yourTableName where yourColumnName1=yourValue1 and yourColumnName2=yourValue2 and yourColumnName3=yourValue3;

让我们首先创建一个表-

mysql> create table DemoTable
   (
   StudentId int NOT NULL AUTO_INCREMENT PRIMARY KEY,
   StudentName varchar(20),
   StudentAge int,
   StudentCountryName varchar(40)
   );

使用插入命令在表中插入一些记录-

mysql> insert into DemoTable(StudentName,StudentAge,StudentCountryName) values('John',23,'US');
mysql> insert into DemoTable(StudentName,StudentAge,StudentCountryName) values('Carol',21,'UK');
mysql> insert into DemoTable(StudentName,StudentAge,StudentCountryName) values('John',21,'US');
mysql> insert into DemoTable(StudentName,StudentAge,StudentCountryName) values('John',21,'AUS');

使用select语句显示表中的所有记录-

mysql> select *from DemoTable;

输出结果

+-----------+-------------+------------+--------------------+
| StudentId | StudentName | StudentAge | StudentCountryName |
+-----------+-------------+------------+--------------------+
| 1         | John        | 23         | US                 |
| 2         | Carol       | 21         | UK                 |
| 3         | John        | 21         | US                 |
| 4         | John        | 21         | AUS                |
+-----------+-------------+------------+--------------------+
4 rows in set (0.00 sec)

以下是MySQL中多个AND条件的查询-

mysql> select *from DemoTable where StudentName="John" and StudentAge=21 and StudentCountryName="AUS";

输出结果

+-----------+-------------+------------+--------------------+
| StudentId | StudentName | StudentAge | StudentCountryName |
+-----------+-------------+------------+--------------------+
| 4         | John        | 21         | AUS                |
+-----------+-------------+------------+--------------------+
1 row in set (0.00 sec)