--創(chuàng)建數(shù)據(jù)庫(kù)(文件：主要數(shù)據(jù)文件mdf==1，次要數(shù)據(jù)文件ndf>=0，日志文件ldf>=1)
--文件組：當(dāng)1mdf,5個(gè)ndf(1,2,2),10個(gè)ldf(3,3,4),將它們分成多個(gè)組存放
CREATE database studb;
--創(chuàng)建表teacher,student
create table teacher
(
tid int(10) primary key auto_increment,
tname varchar(20),
tage int(10)
);
use studb;
create table student
(
sid int(10) primary key auto_increment,
sname varchar(20),
sage int(10),
tid int(10) REFERENCES teacher(tid)
);
--外鍵約束：你問(wèn)張三的老師是誰(shuí)？？
--select teacher.tname from teacher,student where student.sname = '張三'
select t.tname from teacher t,student s where s.sname = '張三' and t.tid = s.tid
--創(chuàng)建課程表
create table course
(
cid int(10) primary key,
cname varchar(20),
tid int(10) REFERENCES teacher(tid)
);
--創(chuàng)建分?jǐn)?shù)表
create table sc
(
scid int(10) primary key,
sid int(10) REFERENCES student(sid),
cid int(10) REFERENCES course(cid),
score int(10)
);
--聯(lián)合查詢(xún)：等值查詢(xún)
--1..
select c.cname from course c,student s,sc where s.sname = '小張'
and s.sid = sc.sid and c.cid = sc.cid;
--2..
select sname from student s,course c,sc where c.cname='android' and sc.score>=60
and s.sid = sc.sid and c.cid = sc.cid;
--3..
--子查詢(xún)：當(dāng)條件也要查詢(xún)的時(shí)候,我只知道學(xué)號(hào)，我不知道"小張"這個(gè)字段,那你知道小張的學(xué)號(hào) 嗎
delete from sc where sid = (select sid from student where sname = '小張');
--子查詢(xún)中間的符號(hào)一定是父查詢(xún)與子查詢(xún)兩張表關(guān)聯(lián)的字段(一般是主外鍵)
--4..
update sc set score=score+5 where cid=????;
select tid from teacher where tname='李老師' ==1
select cname from course where tid = 1 ==課程名字，李老師教的
select cid from course where cname='android' ==課程ID
update sc set score=score+5 where cid=
(
select cid from course where cname=
(
select cname from course where tid =
(
select tid from teacher where tname='李老師'
)
)
);
您可能感興趣的文章:- SQL查詢(xún)語(yǔ)句通配符與ACCESS模糊查詢(xún)like的解決方法
- SQL Server SQL高級(jí)查詢(xún)語(yǔ)句小結(jié)
- SQLSERVER查詢(xún)所有數(shù)據(jù)庫(kù)名，表名，和字段名的語(yǔ)句
- mysql like查詢(xún)字符串示例語(yǔ)句
- MySql日期查詢(xún)語(yǔ)句詳解
- mysql分頁(yè)原理和高效率的mysql分頁(yè)查詢(xún)語(yǔ)句
- 用SQL語(yǔ)句查詢(xún)數(shù)據(jù)庫(kù)中某一字段下相同值的記錄方法
- 只有兩個(gè)字段用一個(gè)sql語(yǔ)句查詢(xún)出某個(gè)學(xué)生的姓名、成績(jī)以及在表中的排名
