1、将下列语句复制到sqlyog的询问栏
/*!40101 SET NAMES utf8 */;
create table `t_student` (
`id` double ,
`stuName` varchar (60),
`age` double ,
`sex` varchar (30),
`gradeName` varchar (60)
);
insert into `t_student` (`id`, `stuName`, `age`, `sex`, `gradeName`) values(‘1‘,‘张三‘,‘23‘,‘男‘,‘一年级‘);
insert into `t_student` (`id`, `stuName`, `age`, `sex`, `gradeName`) values(‘2‘,‘张三丰‘,‘25‘,‘男‘,‘二年级‘);
insert into `t_student` (`id`, `stuName`, `age`, `sex`, `gradeName`) values(‘3‘,‘李四‘,‘23‘,‘男‘,‘一年级‘);
insert into `t_student` (`id`, `stuName`, `age`, `sex`, `gradeName`) values(‘4‘,‘王五‘,‘22‘,‘男‘,‘三年级‘);
insert into `t_student` (`id`, `stuName`, `age`, `sex`, `gradeName`) values(‘5‘,‘珍妮‘,‘21‘,‘女‘,‘一年级‘);
insert into `t_student` (`id`, `stuName`, `age`, `sex`, `gradeName`) values(‘6‘,‘李娜‘,‘26‘,‘女‘,‘二年级‘);
insert into `t_student` (`id`, `stuName`, `age`, `sex`, `gradeName`) values(‘7‘,‘王峰‘,‘20‘,‘男‘,‘三年级‘);
insert into `t_student` (`id`, `stuName`, `age`, `sex`, `gradeName`) values(‘8‘,‘梦娜‘,‘21‘,‘女‘,‘二年级‘);
insert into `t_student` (`id`, `stuName`, `age`, `sex`, `gradeName`) values(‘9‘,‘小黑‘,‘22‘,‘男‘,‘一年级‘);
insert into `t_student` (`id`, `stuName`, `age`, `sex`, `gradeName`) values(‘10‘,‘追风‘,‘25‘,‘男‘,‘二年级‘);
insert into `t_student` (`id`, `stuName`, `age`, `sex`, `gradeName`) values(‘11‘,‘小小张三‘,‘21‘,NULL,‘二年级‘);
insert into `t_student` (`id`, `stuName`, `age`, `sex`, `gradeName`) values(‘12‘,‘小张三‘,‘23‘,‘男‘,‘二年级‘);
insert into `t_student` (`id`, `stuName`, `age`, `sex`, `gradeName`) values(‘13‘,‘张三锋小‘,‘24‘,NULL,‘二年级‘);
这样就会在选定的数据库db_student里创建一张t_student表。
注:查询语句写在询问栏后,全选或者光标在语句中,再点击执行查询(F9)按钮,就可以在下方的结果栏看到查询结果。
2、查询所有字段
SELECT id,stuName,age,sex,gradeName FROM t_student;
SELECT * FROM t_student;
3、查询指定字段
SELECT id,stuName FROM t_student;
4、Where条件查询
SELECT * FROM t_student WHERE id=1;
SELECT * FROM t_student WHERE age>22;
5、带IN关键字查询
SELECT * FROM t_student WHERE age IN (21,23);
SELECT * FROM t_student WHERE age NOT IN (21,23);
6、带BETWEEN AND的范围查询
SELECT * FROM t_student WHERE age BETWEEN 22 AND 24;
SELECT * FROM t_student WHERE age NOT BETWEEN 22 AND 24;
SELECT * FROM t_student WHERE age NOT BETWEEN 22 AND 24 ORDER BY id DESC;
7、带LIKE的模糊查询
SELECT * FROM t_student WHERE stuName LIKE ‘珍妮‘;
SELECT * FROM t_student WHERE stuName LIKE ‘张三%‘;
SELECT * FROM t_student WHERE stuName LIKE ‘张三_‘;
SELECT * FROM t_student WHERE stuName LIKE ‘张三__‘;
SELECT * FROM t_student WHERE stuName LIKE ‘%张三%‘;
8、空值查询
SELECT * FROM t_student WHERE sex IS NULL;
SELECT * FROM t_student WHERE sex IS NOT NULL;
9、带AND的多条件查询
SELECT * FROM t_student WHERE gradeName=‘一年级‘ AND age=23;
10、带OR的多条件查询
SELECT * FROM t_student WHERE gradeName=‘一年级‘ OR age=23;
11、DISTINCT去重复查询
SELECT DISTINCT gradeName FROM t_student;
12、对查询结果排序
默认升序:
SELECT * FROM t_student ORDER BY age ASC;
SELECT * FROM t_student ORDER BY age DESC;
13、GROUP BY分组查询
SELECT gradeName, GROUP_CONCAT(stuName) FROM t_student GROUP BY gradeName;
SELECT gradeName,COUNT(stuName) FROM t_student GROUP BY gradeName;
SELECT gradeName,COUNT(stuName) FROM t_student GROUP BY gradeName HAVING COUNT(stuName)>3;
SELECT gradeName,COUNT(stuName) FROM t_student GROUP BY gradeName WITH ROLLUP;
SELECT gradeName,GROUP_CONCAT(stuName) FROM t_student GROUP BY gradeName WITH ROLLUP;
注:group_concat(),手册上说明:该函数返回带有来自一个组的连接的非NULL值的字符串结果
14、LIMIT分页查询
SELECT * FROM t_student LIMIT 0,5;
SELECT * FROM t_student LIMIT 5,5;
SELECT * FROM t_student LIMIT 10,5;