SQL语句大全-百度百科
SQL HAVING 子句,having百度
MSSQL数据库的字段类型总结
数据库中的聚合函数
MYSQL语句大全
尚学堂数据库学习笔记
Oracle中的Schema和User （详解，赞！该作者的其他帖子也很好）
64位WIN7+oracle11g+plsql安装完全卸载Oracle 11g R2
win7旗舰版（64位）环境下oracle11g的安装方法 （按照此方法安装的 plsql无法使用Inport Tables 和 Export Tables功能操作dmp文件）
PL/SQL Developer连接本地Oracle 11g 64位数据库
（四）多对多模式 （以权限控制作为例子学习较好）
数据库三大范式详解 （去繁就简，记住概要意思）
数据库范式（1NF 2NF 3NF BCNF）详解
写给开发者看的关系型数据库设计
Oracle 如何修改列的数据类型（alter操作）
oracle SELECT INTO 和 INSERT INTO SELECT
ORACLE中date类型字段的处理
经典SQL练习题
ORACLE创建用户操作
Oracle 建立索引及SQL优化
多表连接子查询;left join、right join、inner join的区别
修改SQL数据库中表字段类型时，报“一个或多个对象访问此列”错误的解决方法
用一条insert语句来插入多行数据
进入数据库use student;创建学生表create table student(Sno char(9) primary key,Sname char(20) unique,Ssex char(2),Sage smallint,Sdept char(20));创建课程表create table Course(Cno char(4) primary key,Cname char(40),Cpno char(4),Ccredit smallint);创建学生选课表create table SC(Sno char(4),Cno char(4),Primary key (Sno,Cno));找出这个数据库中所有的表select name FROM sysobjects WHERE type='U'显示出表中所有数据select * from student;select * from Course;select * from SC;插入一条记录（'200215128'，'1'）insert into SC(Sno,Cno) values ('200215128','1');一次性插入多行数据，用insert into 表名 values 的形式无法实现，用all和不用有什么区别呢？insert into SC (Sno,Cno,Grade) select 200215121,1,92 union allselect 200215121,2,85 union allselect 200215121,3,88 union allselect 200215122,2,90 union allselect 200215122,3,80查询成绩在80-90的学生信息select * from student where Sno in(select Sno from SC where Grade between 80 and 90);查询所以年龄在20岁以下的学生姓名及其年龄select Sname,Sage from student where Sage < 20;查询年龄不再20~23岁之间的学生的姓名、系别和年龄select Sname,Sdept,Sage from student where Sage not between 18 and 19查询所有姓刘的学生的姓名、学号和性别select Sname,Sno,Ssex from student where Sname like '刘%'将计算机科学系全体学生的成绩置零update SC set Grade = 0 where 'CS'=(select Sdept from student where student.Sno = SC.Sno);查询计算机科学系的学生及年龄不大于19岁的学生，两种语句select * from student where Sdept = 'CS' or Sage <= 19;select * from student where Sdept = 'CS' union select * from student where Sage <= 19;查询其他系中比计算机科学系某一学生年龄小的学生姓名和年龄select Sname,Sage,Sdept from student where Sage < any (select Sage from student where Sdept = 'CS') and Sdept <> 'CS';删除学号为200215128的学生记录delete from SC where Sno = '200215128';删除计算机科学系所有学生的选课记录，两种语句，有什么区别？in语句效率较低，子查询效率较join语句低delete from SC where Sno in (select Sno from student where Sdept = 'CS');delete from SC where 'CS' = (select Sdept from student where student.Sno = SC.Sno);select * from SC where 'CS' = (select Sdept from student where student.Sno = SC.Sno);select * from SC left join student on SC.Sno = student.Sno where Sdept='CS'如果有聚合函数或者group by，字段必须在其中之一内，order by默认是asc顺序select count(sno) as count,cno from SC group by cno order by count desc select count(sno) as 统计,cno from SC group by cno order by 统计;查询与"刘晨"在同一个系学习的学生，两种语句，有什么区别？in考虑重名情况select * from student where Sdept = (select Sdept from student where Sname = '刘晨');select * from student where Sdept in (select Sdept from student where Sname = '刘晨');平均函数,distinct统计非重复非空字段select avg(Sage) from student where Sdept = 'MA';select count(distinct Sdept),avg(Sage),sum(Sage),min(Sage),max(Sage) from student;
