1. 查询所有数据：
select * from 表名;
select * from exam_books;
2.按照一定的条件查找：
select * from 表名 where 条件;
select * from exam_books where id<20;
3.范围条件查询：
select * from 表名 where 字段 between 值1 and 值2 ;
select * from exam_books where id<20 and id>10;
select * from exam_books where id between 10 and 20;
select * from exam_books where addtime between '2011-03-17 00:00:00' and '2011-03-18 00:00:00';
4.模糊查询：
select * from 表名 where 字段 like '%条件%';
select * from exam_books where bookname like '%马克思%';
select * from exam_books where bookname like '马__';
(查询书名中第一个字是“马”，后面有两个字)
%和_叫做通配符
5.复合查询：
select * from 表名 where 条件 and 另一个条件;
select * from exam_questions where coursecode = '03706' and chapterid = 2;
6.查询个数：
select count(*) from 表名 where 条件
select count(*) as 别名 from exam_questions where coursecode = '03706' and chapterid = 2;
7.查询结果按顺序排列：
正序、倒序（asc/desc）
select * from 表名 where 条件 order by 字段 desc/asc;
select * from exam_questions where coursecode = '03706' order by chapterid;
8、按照limit查找某个范围内的数据：
SELECT * FROM exam_questions order by id asc limit 0, 15;（代表查找出的第一页的信息）
SELECT * FROM exam_questions order by id asc limit 15, 15;（代表查找出的第二页的信息）
【备注：】limit后面的两个数字中：第一个代表偏移量，第二个代表每页展示的数量
偏移量 = （当前页码数-1） * 每页显示条数
SELECT 字段 AS 别名 FROM 表名 WHERE... ORDER BY ... LIMIT....
10、group by分组查询
select name ,sum(score) from students group by name having name='xxx'
二. 删除数据：delete
delete from 表名 where 条件;
delete from exam_questions where id<2000;
delete from exam_questions where coursecode='00041' and chapterid=1;
DELETE FROM 表名 WHERE子句
三.插入新数据：insert
insert into 表名(字段) values(值);
insert into exam_weburl(webname , weburl , info , bigtypeid) values('人人网', 'renren.com' , '这个网站不错' , 3);
作者: psuugdufnm 时间: 2016-4-11 17:24
四.更新数据：update
update 表名 set 字段1=值1, 字段2=值2 where 条件;
update exam_weburl set info='这个网站不太好' where id=73;
update exam_weburl set webname='人人2', weburl='www.renren.com' where id=73;