中国人民大学信息学院计算机系

An Introduction to Database System

SQL


SQL3.1 SQL3.2 3.3 3.4 3.5 3.6 3.7 SQL3.8


3.1 SQLSQL1. 2. 3. 4. 5.


5.


3.1 SQL

SQL

CREATEDROPALTER

SELECT

INSERTUPDATE

DELETE

GRANTREVOKE

SQL3.1 SQL3.2 3.3 3.4 3.5 3.6 3.7 SQL3.8


3.2


3.2 SQL

CREATE TABLE

DROP TABLE

ALTER TABLE

CREATE VIEW

DROP VIEW

CREATE INDEX

DROP INDEX

3.2.1 CREATE TABLE [ ] [ [ ] ] [ ]


[1] StudentSnoSnameSsexSageSdept CREATE TABLE Student (Sno CHAR(5) NOT NULL UNIQUE Sname CHAR(20) UNIQUE Ssex CHAR(1) Sage INT Sdept CHAR(15))


PRIMARY KEYUNIQUENOT NULL

PRIMARY KEY UNIQUE


[2] SCSnoCnoGrade(Sno, Cno)CREATE TABLE SC( Sno CHAR(5) , Cno CHAR(3) , Grade int, Primary key (Sno, Cno));


DROP TABLE ;


[5] Student DROP TABLEStudent ;


ALTER TABLE [ ADD [ ] ][ DROP ][ MODIFY ]

ADDDROPMODIFY


[2] Student

ALTER TABLE Student ADD Scome DATE


/:()ALTER TABLE Student Drop Scome


[3]

ALTER TABLE Student MODIFY Sage SMALLINT


[4] ALTER TABLE Student DROP UNIQUE(Sname)


3.2.2 DBADBMS PRIMARY KEY UNIQUE DBMS DBMS


CREATE [UNIQUE] [CLUSTER] INDEX ON ([][,[] ])ASCDESCASCUNIQUECLUSTER


[6] -StudentCourseSCStudentCourseSC

CREATE UNIQUE INDEX Stusno ON Student(Sno)CREATE UNIQUE INDEX Coucno ON Course(Cno)CREATE UNIQUE INDEX SCno ON SC(Sno ASCCno DESC)


UNIQUEUNIQUEDBMSUNIQUE


CREATE CLUSTER INDEX Stusname ON Student(Sname)StudentSnameStudentSname


DROP INDEX [7] StudentStusnameDROP INDEX Stusname


3.3 3.3.1 3.3.2 3.3.3 3.3.4 3.3.5 3.3.6


3.3.1 SELECT [ALL|DISTINCT] [] FROM [ ] [ WHERE ][ GROUP BY [ HAVING ] ][ ORDER BY [ ASC|DESC ] ]


SELECTFROM()WHERE GROUP BYHAVINGORDER BY


-Student(SnoSnameSsexSageSdept)Course(CnoCnameCpnoCcredit) SC(SnoCnoGrade)


3.3 3.3.1 3.3.2 3.3.3 3.3.4 3.3.5 3.3.6


3.3.2


[1] SELECT SnoSnameFROM Student[2] SELECT SnameSnoSdeptFROM Student


[3] SELECT SnoSnameSsexSageSdept FROM Student SELECT *FROM Student


3. SELECT


3. [4] SELECT Sname2000-SageFROM Student Sname 2000-Sage --------- ------------- 1976 1977 1978 1978


3. [5]

SELECT Sname'Year of Birth: '2000-Sage ISLOWER(Sdept)FROM Student


Sname 'Year of Birth:' 2000-Sage ISLOWER(Sdept) ------- ---------------- --------- -------------- Year of Birth: 1976 cs Year of Birth: 1977 is Year of Birth: 1978 ma Year of Birth: 1977 is


[5.1] SELECT Sname NAME'Year of Birth: BIRTH 2000-Sage BIRTHDAYISLOWER(Sdept) DEPARTMENTFROM Student NAME BIRTH BIRTHDAY DEPARTMENT ------- ---------------- ------------- ------------------ Year of Birth: 1976 cs Year of Birth: 1977 is Year of Birth: 1978 ma Year of Birth: 1977 is


1. SELECTDISTINCTSC Sno Cno Grade ------- ------- ------- 95001 1 92 95001 2 85 95001 3 88 95002 2 90 95002 3 80


ALL DISTINCT [6] (1) SELECT Sno FROM SC;( ALL) SELECT ALL Sno FROM SC; Sno ------- 95001 95001 95001 95002 95002


(2) SELECT DISTINCT Sno FROM SC; Sno ------- 95001 95002


DISTINCTSELECT DISTINCT CnoDISTINCT GradeFROM SC; SELECT DISTINCT CnoGrade FROM SC;


2.WHERE


(1) WHERE=>=!= 20


(2) BETWEEN AND NOT BETWEEN AND [10] 20~232023 SELECT SnameSdeptSageFROM StudentWHERE Sage BETWEEN 20 AND 23


[11] 20~23

SELECT SnameSdeptSageFROM StudentWHERE Sage NOT BETWEEN 20 AND 23


(3) IN , NOT IN [12]ISMA CSSELECT SnameSsexFROM StudentWHERE Sdept IN ( 'IS''MA''CS' );


(3) [13] SELECT SnameSsexFROM Student WHERE Sdept NOT IN ( 'IS''MA''CS' );


(4) [NOT] LIKE [ESCAPE ] = LIKE != < > NOT LIKE


% () 0a%babacbaddgbab _ () a_bab3acbafb


ESCAPE

% _ ESCAPE ''


1) [14] 95001 SELECT * FROM Student WHERE Sno LIKE '95001' SELECT * FROM Student WHERE Sno = '95001'


2)

[15] SELECT SnameSnoSsex FROM Student WHERE Sname LIKE %


[16] "" SELECT Sname FROM Student WHERE Sname LIKE '__'


[17] 2"" SELECT SnameSno FROM Student WHERE Sname LIKE '__%'


[18] SELECT SnameSnoSsex FROM Student WHERE Sname NOT LIKE '%'


3) [19] DB_Design SELECT CnoCcredit FROM Course WHERE Cname LIKE 'DB\_Design' ESCAPE '\'


()

[20] "DB_"3 i SELECT * FROM Course WHERE Cname LIKE 'DB\_%i_ _' ESCAPE ' \ '


(5) IS NULL IS NOT NULL IS NULL = NULL [21] SELECT SnoCno FROM SC WHERE Grade IS NULL


()

[22]

SELECT SnoCno FROM SC WHERE Grade IS NOT NULL


(6) AND OR ANDOR [NOT] IN [NOT] BETWEEN AND


[23] 20 SELECT Sname FROM Student WHERE Sdept= 'CS' AND Sage

[12][12] ISMACSSELECT SnameSsexFROM StudentWHERE Sdept IN ( 'IS''MA''CS' )SELECT SnameSsexFROM StudentWHERE Sdept= ' IS ' OR Sdept= ' MA' OR Sdept= ' CS '


[10][10] 20~232023 SELECT SnameSdeptSageFROM StudentWHERE Sage BETWEEN 20 AND 23 SELECT SnameSdeptSageFROM Student WHERE Sage>=20 AND Sage

ORDER BY ASCDESCASCDESC


[24] 3

SELECT SnoGrade FROM SC WHERE Cno= ' 3 ' ORDER BY Grade DESC


Sno Grade ------- ------- 95010 95024 95007 92 95003 82 95010 82 95009 75 95014 61 95002 55


[25]

SELECT * FROM Student ORDER BY SdeptSage DESC


5COUNT[DISTINCT|ALL] *COUNT[DISTINCT|ALL] SUM[DISTINCT|ALL] AVG[DISTINCT|ALL]


MAX[DISTINCT|ALL] MIN[DISTINCT|ALL] DISTINCTALLALL


[26] SELECT COUNT(*) FROM Student[27] SELECT COUNT(DISTINCT Sno) FROM SCDISTINCT


[28] 1 SELECT AVG(Grade) FROM SC WHERE Cno= ' 1 '[29] 1 SELECT MAX(Grade) FROM SC WHER Cno= ' 1 '


GROUP BY


GROUP BY[30] SELECT CnoCOUNT(Sno) FROM SC GROUP BY Cno Cno COUNT(Sno) 1 22 2 34 3 44 4 33 5 48


GROUP BYGROUP BYSELECT


HAVING[31] 3 SELECT Sno FROM SC GROUP BY Sno HAVING COUNT(*) >3


[32] 390 90 SELECT Sno, COUNT(*) FROM SC WHERE Grade>=90 GROUP BY Sno HAVING COUNT(*)>=3;


HAVINGHAVINGHAVINGWHEREWHEREHAVING


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中国人民大学信息学院计算机系