数据准备工作：
1 CREATE TABLE student( 2 sid INT PRIMARY KEY AUTO_INCREMENT, 3 `name` VARCHAR(10), 4 age INT, 5 city VARCHAR(10) 6 ); 7 8 INSERT INTO student VALUES (NULL,"张三",20,"广州"); 9 INSERT INTO student VALUES (NULL,"李四",22,"深圳"); 10 INSERT INTO student VALUES (NULL,"王五",17,"佛山"); 11 INSERT INTO student VALUES (NULL,"赵六",24,"广州"); 12 INSERT INTO student VALUES (NULL,"孙七",20,NULL);
一、简单查询
语法：select [distinct] * | 列名1,列名2 from 表;
1.1 查询所有学生
查询指令：select * from student;
mysql> select * from student; +-----+--------+------+--------+ | sid | name | age | city | +-----+--------+------+--------+ | 1 | 张三 | 20 | 广州 | | 2 | 李四 | 22 | 深圳 | | 3 | 王五 | 17 | 佛山 | | 4 | 赵六 | 24 | 广州 | | 5 | 孙七 | 20 | NULL | +-----+--------+------+--------+ 5 rows in set (0.00 sec)
1.2 查询学生姓名和年龄
查询指令：select name,age from student;
mysql> select name,age from student; +--------+------+ | name | age | +--------+------+ | 张三 | 20 | | 李四 | 22 | | 王五 | 17 | | 赵六 | 24 | | 孙七 | 20 | +--------+------+ 5 rows in set (0.00 sec)
1.3 运算查询：将所有学生的年龄+1进行显示
查询指令：select name,age+1 from student;
mysql> select name,age+1 from student; +--------+-------+ | name | age+1 | +--------+-------+ | 张三 | 21 | | 李四 | 23 | | 王五 | 18 | | 赵六 | 25 | | 孙七 | 21 | +--------+-------+ 5 rows in set (0.00 sec)
1.4 别名查询：将列名name,age分别用中文显示
查询指令：select name as 姓名,age as 年龄 from student;
mysql> select name as 姓名,age as 年龄 from student; +--------+--------+ | 姓名 | 年龄 | +--------+--------+ | 张三 | 20 | | 李四 | 22 | | 王五 | 17 | | 赵六 | 24 | | 孙七 | 20 | +--------+--------+ 5 rows in set (0.00 sec)
二、条件查询
语法：select [distinct] * | 列名1,列名2 from 表 where 条件;
2.1 查询年龄大于20的学生
查询指令：select * from student where age > 20;
mysql> select * from student where age > 20; +-----+--------+------+--------+ | sid | name | age | city | +-----+--------+------+--------+ | 2 | 李四 | 22 | 深圳 | | 4 | 赵六 | 24 | 广州 | +-----+--------+------+--------+ 2 rows in set (0.00 sec)
2.2 查询年龄是18到22的学生
查询指令：select * from student where age between 18 and 22;
mysql> select * from student where age between 18 and 22; +-----+--------+------+--------+ | sid | name | age | city | +-----+--------+------+--------+ | 1 | 张三 | 20 | 广州 | | 2 | 李四 | 22 | 深圳 | | 5 | 孙七 | 20 | NULL | +-----+--------+------+--------+ 3 rows in set (0.00 sec)
2.3 查询地址是广州或深圳的学生
查询指令：select * from student where city in ("广州","深圳");
mysql> select * from student where city in ("广州","深圳"); +-----+--------+------+--------+ | sid | name | age | city | +-----+--------+------+--------+ | 1 | 张三 | 20 | 广州 | | 2 | 李四 | 22 | 深圳 | | 4 | 赵六 | 24 | 广州 | +-----+--------+------+--------+ 3 rows in set (0.00 sec)
2.4 查询姓孙的学生
查询指令：select * from student where name like "孙%";
mysql> select * from student where name like "孙%"; +-----+--------+------+------+ | sid | name | age | city | +-----+--------+------+------+ | 5 | 孙七 | 20 | NULL | +-----+--------+------+------+ 1 row in set (0.00 sec)
2.5 查询地址不为空的学生
查询指令：select * from student where city IS NOT NULL;
mysql> select * from student where city IS NOT NULL; +-----+--------+------+--------+ | sid | name | age | city | +-----+--------+------+--------+ | 1 | 张三 | 20 | 广州 | | 2 | 李四 | 22 | 深圳 | | 3 | 王五 | 17 | 佛山 | | 4 | 赵六 | 24 | 广州 | +-----+--------+------+--------+ 4 rows in set (0.00 sec)
2.6 查询地址为广州或深圳，且年龄大于20的学生
查询指令：select * from student where city in ("广州","深圳") and age > 20;
mysql> select * from student where city in ("广州","深圳") and age > 20; +-----+--------+------+--------+ | sid | name | age | city | +-----+--------+------+--------+ | 2 | 李四 | 22 | 深圳 | | 4 | 赵六 | 24 | 广州 | +-----+--------+------+--------+ 2 rows in set (0.00 sec)
2.7 查询地址不是广州或深圳的学生
查询指令：select * from student where city not in ("广州","深圳");
mysql> select * from student where city not in ("广州","深圳"); +-----+--------+------+--------+ | sid | name | age | city | +-----+--------+------+--------+ | 3 | 王五 | 17 | 佛山 | +-----+--------+------+--------+ 1 row in set (0.00 sec)