mysql实践（六）

条件：

select * from test where nid > 3;

select * from test where nid between 3 and 6;

select * from test where nid in (1,2,4,5);

select * from test where nid = 3 and name ='eric';

select * from test where dept in (select department from dept);

通配符：

select * from test where name like "%eric_";

分页：

select * from test limit 5;

select * from test limit 4,5

select * from test limit 5 offset 4;

组合：

select name from userinfo union select deptment from dept;

select name from userinfo union all select deptment from dept;

排序：

select * from test order by nid asc;

select * from test order by nid desc;

select nid,name from test order by nid asc, name desc;

分组：

select dept,count(*), avg(age),max(age),min(age),sum(age) from userinfo where nid > 3 group by dept order by dept;

group by 在where之后，order by 之前

连表：

select userinfo.dept,dept.department from userinfo,dept where userinfo.dept=dept.nid;

select userinfo.*,dept.department from userinfo left join dept on userinfo.dept=dept.nid;