SQL学习笔记1

2018.10.15：周一

 

-- 返回前5个数据

SELECT TOP 5 *

FROM Student;

 

-- 返回前50%的数据

SELECT TOP 50 PERCENT *

FROM Student;

 

-- 以"C"或"P"开头

SELECT *

FROM Student

WHERE Subject LIKE '[CP]%';

 

-- 不以"C"或"P"开头

SELECT *

FROM Student

-- WHERE Subject LIKE '[^CP]%';

-- WHERE Subject LIKE '[!CP]%'; //不行

WHERE Subject NOT LIKE '[CP]%';

 

-- 以"A-D"开头

SELECT *

FROM Student

WHERE Subject LIKE '[A-D]%';

 

--选择科目是java和c#的所有人

SELECT *

FROM Student

WHERE Subject IN ('Java','C#');

-- WHERE Subject NOT IN ('Java','C#');

 

--选择范围之间

SELECT *

FROM Student

WHERE StuAge BETWEEN 22 AND 24;

-- WHERE StuAge NOT BETWEEN 22 AND 24;

 

SELECT *

FROM Student

WHERE (StuAge BETWEEN 22 AND 24) AND Subject NOT IN('Java');

 

SELECT *

FROM Student

WHERE StuName BETWEEN '曹操' AND '关羽'

ORDER BY StuName;

 

--若有日期的话

--SELECT * FROM Student WHERE Date BETWEEN #07/04/1996# AND #07/09/1996#;

 

-- 连接

-- 内

SELECT *

FROM Student INNER JOIN UserLogin

ON Student.StuName=UserLogin.UserName;

-- 左外

SELECT *

FROM Student LEFT JOIN UserLogin

ON Student.StuName=UserLogin.UserName;

-- 右外

SELECT *

FROM Student RIGHT JOIN UserLogin

ON Student.StuName=UserLogin.UserName;

-- 自然

SELECT *

FROM Student FULL JOIN UserLogin

ON Student.StuName=UserLogin.UserName;

 

-- 自连接

SELECT S.StuName AS NAME1,U.UserName AS NAME2

FROM Student S,UserLogin U

WHERE S.ID =U.ID;

 

--组合并去重复

SELECT StuName AS NAME

FROM Student

UNION

SELECT UserName

FROM UserLogin

ORDER BY StuName;

 

--组合但未去重复

SELECT StuName AS NAME

FROM Student

UNION ALL

SELECT UserName

FROM UserLogin

ORDER BY StuName;

 

--复制表中的数据到另一个新建表

SELECT *

INTO Student1015

FROM Student;

 

-- 复制到另一个数据库//貌似不可行

SELECT *

INTO Student181015 IN 'Nwind.mdb'

FROM Student;

 

--只复制一些列到新表

SELECT StuName,StuAge

INTO Student1015_1

FROM Student;

 

--复制多个表中信息插入新表

SELECT UserLogin.ID,Student.StuName,Student.StuAge

INTO Student1015_2

FROM Student INNER JOIN UserLogin

ON Student.StuName=UserLogin.UserName

ORDER BY UserLogin.ID;

 

--建一个空表，查询返回时无返回值

SELECT *

INTO newtable

FROM Student

WHERE 1=0;

 

--把指定列插入另一个表的指定列

INSERT INTO Student1015_2(ID,StuName,StuAge)

SELECT TOP 3 Student.ID,Student.Subject,Student.StuAge

FROM Student

WHERE Student.Subject='c#';

 

--删除表

DROP TABLE Student1015_2;

--只删除表中数据

TRUNCATE TABLE Student1015_2;

 

--添加列

ALTER TABLE Student1015_1

ADD STU15 DATE;

--删除列

ALTER TABLE Student1015_1

DROP COLUMN STU15;

--更改列

ALTER TABLE Student1015_1

ALTER COLUMN STU15 DATETIME;

 

--创建视图

GO

CREATE VIEW [MYSTUDENT] AS

SELECT ID,StuName

FROM Student1015

WHERE StuAge=24;

GO

 

GO

CREATE VIEW [DYMYSTUDENT] AS

SELECT ID,StuName

FROM Student1015

WHERE StuAge>(SELECT AVG(StuAge) FROM Student1015);

GO

--查询视图

GO

SELECT *

FROM [MYSTUDENT]

GO

--更新视图//貌似不行

GO

CREATE OR REPLACE VIEW [MYSTUDENT] AS

SELECT ID,StuName

FROM Student1015

WHERE StuAge=23;

GO

--删除视图

DROP VIEW [MYSTUDENT];

 

--查询时间

SELECT *

FROM Student1015_1

WHERE STU15='2018-10-15';