python-day11 Mysql 數據類操作
阿新 • • 發佈：2017-07-10
通配符 sid alex line htm having core count ace
數據類操作####
insert#=====
insert into student(sname,gender,class_id) values(‘ls‘,‘男‘,1)
insert into class(caption) values(‘python1班‘)
insert into teacher(tname) values(‘alex‘)
insert into course(cname,tearch_id) values(‘python‘,1)
insert into score(student_id,corse_id,number) values(4,3,60);
update=====
update score set number=87 where sid=1;
delete===
delete from score where sid=1;
select====================
select * from 表
select * from 表 where id > 1
select nid,name,gender as gg from 表 where id > 1
a、條件
select * from 表 where id > 1 and name != ‘alex‘ and num = 12;
select * from 表 where id between 5 and 16;
select * from 表 where id in (11,22,33)
select * from 表 where id not in (11,22,33)
select * from 表 where id in (select nid from 表)
b、通配符
select * from 表 where name like ‘ale%‘ - ale開頭的所有（多個字符串）
select * from 表 where name like ‘ale_‘ - ale開頭的所有（一個字符）
c、限制
select * from 表 limit 5; - 前5行 select * from 表 limit 4,5; - 從第4行開始的5行
select * from 表 limit 5 offset 4 - 從第4行開始的5行
d、排序
select * from 表 order by 列 asc - 根據 “列” 從小到大排列
select * from 表 order by 列 desc - 根據 “列” 從大到小排列
select * from 表 order by 列1 desc,列2 asc - 根據 “列1” 從大到小排列，如果相同則按列2從小到大排序
e、分組
select num from 表 group by num
select num,nid from 表 group by num,nid
select num,nid from 表 where nid > 10 group by num,nid order nid desc
select num,nid,count(*),sum(score),max(score),min(score) from 表 group by num,nid
select num from 表 group by num having max(id) > 10
特別的：group by 必須在where之後，order by之前
f、連表
無對應關系則不顯示
select A.num, A.name, B.name
from A,B
Where A.nid = B.nid
無對應關系則不顯示
select A.num, A.name, B.name
from A inner join B
on A.nid = B.nid
A表所有顯示，如果B中無對應關系，則值為null
select A.num, A.name, B.name
from A left join B
on A.nid = B.nid
B表所有顯示，如果B中無對應關系，則值為null
select A.num, A.name, B.name
from A right join B
on A.nid = B.nid
g、組合
組合，自動處理重合
select nickname
from A
union
select name
from B
組合，不處理重合
select nickname
from A
union all
select name
from B
其他進階:http://www.cnblogs.com/wupeiqi/articles/5713323.html
python-day11 Mysql 數據類操作