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SQL

Suan Lee

SQL - Suan Lee 2

Introduction to SQL

• “S.Q.L.” or “sequel”

• Supported by all major commercial database systems

• Standardized – many new features over time

• Interactive via GUI or prompt, or embedded in programs

• Declarative, based on relational algebra

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Data Definition Language (DDL)• CREATE TABLE …

• DROP TABLE …

Data Manipulation Language (DML)• SELECT …

• INSERT …

• DELETE …

• UPDATE …

Other Commands

indexes, constraints, views, triggers, transactions, authorization, …

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The Basic SELECT Statement

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SELECT A1,A2,…,AnFROM R1,R2, …,RmWHERE condition

The Basic SELECT Statement

ΠA1, …, An(σ condition(R1×…×Rm)

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• “S.Q.L.” or “sequel”

• Supported by all major commercial database systems

• Standardized – many new features over time

• Interactive via GUI or prompt, or embedded in programs

• Declarative, based on relational algebra

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Basic SELECT Statement

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Basic SELECT Statement

Demo: simple college admissions databaseCollege(cName, state, enrollment)

Student(sID, sName, GPA, sizeHS)

Apply(sID, cName, major, decision)

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• Colleges

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• Students

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• Apply

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SQL Result

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SELECT sID, sName, GPAFROM StudentWHERE GPA > 3.6;

SQL Result

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SELECT sID, sNameFROM StudentWHERE GPA > 3.6;

SQL Result

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SELECT sName, majorFROM Student, ApplyWHERE Student.sID = Apply.sID;

SQL Result

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SELECT sName, majorFROM Student, ApplyWHERE Student.sID = Apply.sID;

duplicate values

duplicate valuesduplicate values

duplicate values

duplicate values

SQL Result

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SELECT DISTINCT sName, majorFROM Student, ApplyWHERE Student.sID = Apply.sID;

SQL Result

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SELECT sName, GPA, decisionFROM Student, ApplyWHERE Student.sID = Apply.sIDAND sizeHS < 1000AND major = 'CS'AND cName = 'Stanford';

SQL

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SELECT cNameFROM College, ApplyWHERE College.cName =

Apply.cNameAND enrollment > 20000AND major = 'CS';

SQL Result

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SELECT cNameFROM College, ApplyWHERE College.cName =


SQL Result

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SELECT College.cNameFROM College, ApplyWHERE College.cName =


SQL Result

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SELECT DISTINCT College.cNameFROM College, ApplyWHERE College.cName =


SQL

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SELECT Student.sID, sName, GPA, Apply.cName, enrollment

FROM Student, College, ApplyWHERE Apply.sID = Student.sIDAND Apply.cName =

College.cName;

SQL Result

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College.cName;

SQL Result

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College.cNameORDER BY GPA DESC;

SQL Result

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College.cNameORDER BY GPA DESC, enrollment;

SQL Result

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SELECT sID, majorFROM ApplyWHERE major LIKE '%bio%';

SQL Result

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SELECT *FROM ApplyWHERE major LIKE '%bio%';

SQL

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SELECT *FROM Student, College;

SQL Result

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SELECT *FROM Student, College;

…

SQL

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SELECT sID, sName, GPA,sizeHS, GPA*(sizeHS/1000.0)

FROM Student;

SQL Result

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SELECT sID, sName, GPA,sizeHS, GPA*(sizeHS/1000.0)

FROM Student;

SQL Result

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SELECT sID, sName, GPA,sizeHS, GPA*(sizeHS/1000.0)AS scaledGPA

FROM Student;

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Table Variables and Set Operators




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Table variables

Set Operators: Union, Intersect, Except

SQL Result

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SELECT Student.sID, sName,GPA, Apply.cName,enrollment

FROM Student, College, Apply

WHERE Apply.sID = Student.sID

AND Apply.cName = College.cName;

SQL Result

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SELECT S.sID, sName,GPA, A.cName,enrollment

FROM Student S, College C, Apply A

WHERE A.sID = S.sIDAND A.cName = C.cName;

SQL

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SELECT S1.sID, S1.sName,S1.GPA, S2.sID, S2.sName,S2.GPA

FROM Student S1, Student S2WHERE S1.GPA = S2.GPA;

SQL Result

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FROM Student S1, Student S2WHERE S1.GPA = S2.GPA;

…

SQL Result

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FROM Student S1, Student S2WHERE S1.GPA = S2.GPAAND S1.sID <> S2.sID;

SQL Result

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FROM Student S1, Student S2WHERE S1.GPA = S2.GPAAND S1.sID < S2.sID;

SQL Result

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SELECT cNameFROM CollegeUNIONSELECT sNameFROM Student;

SQL Result

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SELECT cName AS nameFROM CollegeUNIONSELECT sName AS nameFROM Student;

SQL Result

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SELECT cName AS nameFROM CollegeUNION ALLSELECT sName AS nameFROM Student;

SQL Result

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SELECT cName AS nameFROM CollegeUNION ALLSELECT sName AS nameFROM StudentORDER BY name;

SQL Result

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SELECT sIDFROM ApplyWHERE major = 'CS'INTERSECTSELECT sIDFROM ApplyWHERE major = 'EE‘;

SQL Result

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SELECT A1.sIDFROM Apply A1, Apply A2WHERE A1.sID = A2.sIDAND A1.major = 'CS'AND A2.major = 'EE';

SQL Result

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SELECT A1.sIDFROM Apply A1, Apply A2WHERE A1.sID = A2.sIDAND A1.major = 'CS'AND A2.major = 'EE';

SQL Result

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SELECT DISTINCT A1.sIDFROM Apply A1, Apply A2WHERE A1.sID = A2.sIDAND A1.major = 'CS'AND A2.major = 'EE';

SQL

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SELECT sIDFROM ApplyWHERE major = 'CS'MINUSSELECT sIDFROM ApplyWHERE major = 'EE‘;

SQL Result

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SELECT sIDFROM ApplyWHERE major = 'CS'MINUSSELECT sIDFROM ApplyWHERE major = 'EE‘;

SQL

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SELECT A1.sIDFROM Apply A1, Apply A2WHERE A1.sID = A2.sIDAND A1.major = 'CS'AND A2.major <> 'EE';

SQL

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SELECT A1.sIDFROM Apply A1, Apply A2WHERE A1.sID = A2.sIDAND A1.major = 'CS'AND A2.major <> 'EE';

Result

SQL

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SELECT DISTINCT A1.sIDFROM Apply A1, Apply A2WHERE A1.sID = A2.sIDAND A1.major = 'CS'AND A2.major <> 'EE';

Result

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Subqueries in WHERE




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Expressions involving “subqueries”: nested

Select statements

SQL

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SELECT sID, sNameFROM StudentWHERE sID IN(SELECT sIDFROM ApplyWHERE major = 'CS'

);

SQL

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);

Result

SQL

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SELECT sID, sNameFROM Student, ApplyWHERE Student.sID =

Apply.sIDAND major = 'CS';

SQL

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SELECT sID, sNameFROM Student, ApplyWHERE Student.sID =


Result

SQL

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SELECT Student.sID, sNameFROM Student, ApplyWHERE Student.sID =


Result

SQL

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Result


);

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SQL

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Result

SQL

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SELECT DISTINCT Student.sID,sName

FROM Student, ApplyWHERE Student.sID =


Result

SQL

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SELECT sNameFROM StudentWHERE sID IN(SELECT sIDFROM ApplyWHERE major = 'CS'

);

Result

SQL

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SELECT sNameFROM Student, ApplyWHERE Student.sID =


SQL

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SELECT sNameFROM Student, ApplyWHERE Student.sID =


Result

SQL

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SELECT DISTINCT sNameFROM Student, ApplyWHERE Student.sID =


Result

SQL

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SELECT DISTINCT sNameFROM Student, ApplyWHERE Student.sID =


Result

SELECT DISTINCT Student.sID,sName



SQL

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SELECT GPAFROM StudentWHERE sID IN(SELECT sIDFROM ApplyWHERE major = 'CS'

);

Result

SQL

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SELECT GPAFROM Student, ApplyWHERE Student.sID =


Result

SQL

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SELECT DISTINCT GPAFROM Student, ApplyWHERE Student.sID =


Result

SQL

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SELECT DISTINCT GPAFROM Student, ApplyWHERE Student.sID =


Result

SELECT GPAFROM StudentWHERE sID IN(SELECT sIDFROM ApplyWHERE major = 'CS'

);

SQL

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)AND sID NOT IN(SELECT sIDFROM ApplyWHERE major = 'EE'

);

SQL

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)AND sID NOT IN(SELECT sIDFROM ApplyWHERE major = 'EE'

);

Result

SQL

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)AND NOT sID IN(SELECT sIDFROM ApplyWHERE major = 'EE'

);

Result

SQL

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SELECT cName, stateFROM College C1WHERE EXISTS(SELECT *FROM College C2WHERE C2.state = C1.state

);

SQL

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SELECT cName, stateFROM College C1WHERE EXISTS(SELECT *FROM College C2WHERE C2.state = C1.state

);

Result

SQL

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SELECT cName, stateFROM College C1WHERE EXISTS(SELECT *FROM College C2WHERE C2.state = C1.stateAND C1.cName <> C2.cName

);

SQL

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SELECT cName, stateFROM College C1WHERE EXISTS(SELECT *FROM College C2WHERE C2.state = C1.stateAND C1.cName <> C2.cName

);

Result

SQL

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SELECT cNameFROM College C1WHERE NOT EXISTS(SELECT *FROM College C2WHERE C2.enrollment >

C1.enrollment);

SQL

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SELECT cNameFROM College C1WHERE NOT EXISTS(SELECT *FROM College C2WHERE C2.enrollment >

C1.enrollment);

Result

SQL

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SELECT sNameFROM Student S1WHERE NOT EXISTS(SELECT *FROM Student S2WHERE S2.GPA > S1.GPA

);

SQL

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SELECT sNameFROM Student S1WHERE NOT EXISTS(SELECT *FROM Student S2WHERE S2.GPA > S1.GPA

);

Result

SQL

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SELECT sName, GPAFROM Student S1WHERE NOT EXISTS(SELECT *FROM Student S2WHERE S2.GPA > S1.GPA

);

Result

SQL

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SELECT S1.sName, S1.GPAFROM Student S1, Student S2WHERE S1.GPA > S2.GPA;

SQL

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SELECT S1.sName, S1.GPAFROM Student S1, Student S2WHERE S1.GPA > S2.GPA;

Result

…

SQL

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SELECT DISTINCT S1.sName, S1.GPAFROM Student S1, Student S2WHERE S1.GPA > S2.GPA;

Result

SQL

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SELECT sName, GPAFROM StudentWHERE GPA >= ALL(SELECT GPAFROM Student

);

SQL

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SELECT sName, GPAFROM StudentWHERE GPA >= ALL(SELECT GPAFROM Student

);

Result

SQL

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SELECT sNameFROM Student S1WHERE GPA > ALL(SELECT GPAFROM Student S2WHERE S2.sID <> S1.sID

);

SQL

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SELECT sNameFROM Student S1WHERE GPA > ALL(SELECT GPAFROM Student S2WHERE S2.sID <> S1.sID

);

Result

SQL

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SELECT cNameFROM College C1WHERE enrollment > ALL(SELECT enrollmentFROM College C2WHERE C2.cName <> C1.cName

);

Result

SQL

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SELECT cNameFROM College C1WHERE NOT enrollment <= ANY(SELECT enrollmentFROM College C2WHERE C2.cName <> C1.cName

);

SQL

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SELECT cNameFROM College C1WHERE NOT enrollment <= ANY(SELECT enrollmentFROM College C2WHERE C2.cName <> C1.cName

);

Result

SQL

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SELECT sID, sName, sizeHSFROM StudentWHERE sizeHS > ANY(SELECT sizeHSFROM Student

);

SQL

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SELECT sID, sName, sizeHSFROM StudentWHERE sizeHS > ANY(SELECT sizeHSFROM Student

);

Result

SQL

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SELECT sID, sName, sizeHSFROM Student S1WHERE EXISTS(SELECT *FROM Student S2WHERE S2.sizeHS <

S1.sizeHS);

SQL

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SELECT sID, sName, sizeHSFROM Student S1WHERE EXISTS(SELECT *FROM Student S2WHERE S2.sizeHS <

S1.sizeHS);

Result

SQL

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SELECT sID, sNameFROM StudentWHERE sID = ANY(SELECT sIDFROM ApplyWHERE major = 'CS'

)AND sID <> ANY(SELECT sIDFROM ApplyWHERE major = 'EE'

);

SQL

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)AND NOT sID IN(SELECT sIDFROM ApplyWHERE major = 'EE'

);

Result

SQL

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);

SQL

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);

Result

SQL

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)AND NOT sID = ANY(SELECT sIDFROM ApplyWHERE major = 'EE'

);

SQL

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)AND NOT sID = ANY(SELECT sIDFROM ApplyWHERE major = 'EE'

);

Result

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Subqueries in FROM and SELECT




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Expressions involving “subqueries”: nested

Select statements

SQL

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SELECT sID, sName, GPA, GPA*(sizeHS/1000.0)AS scaledGPA

FROM StudentWHERE GPA*(sizeHS/1000.0)

- GPA > 1.0OR GPA -

GPA*(sizeHS/1000.0) > 1.0;

SQL

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FROM StudentWHERE GPA*(sizeHS/1000.0)

- GPA > 1.0OR GPA -

GPA*(sizeHS/1000.0) > 1.0;

Result

SQL

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FROM StudentWHERE ABS(GPA*(sizeHS/1000.0)

- GPA) > 1.0;

Result

SQL

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SELECT *FROM (SELECT sID, sName, GPA,

GPA*(sizeHS/1000.0)AS scaledGPA

FROM Student) GWHERE ABS (G.scaledGPA - GPA)

> 1.0;

SQL

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SELECT *FROM (SELECT sID, sName, GPA,

GPA*(sizeHS/1000.0)AS scaledGPA

FROM Student) GWHERE ABS (G.scaledGPA - GPA)

> 1.0;

Result

SQL

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SELECT College.cName, state, GPA

FROM College, Apply, Student

WHERE College.cName = Apply.cName

AND Apply.sID = Student.sID

AND GPA >= ALL (SELECT GPAFROM Student, ApplyWHERE Student.sID =

Apply.sIDAND Apply.cName =

College.cName);

SQL

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SELECT College.cName, state, GPA






College.cName);

Result

SQL

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SELECT DISTINCT College.cName, state, GPA






College.cName);

Result

SQL

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SELECT cName, state,( SELECT DISTINCT GPAFROM Apply, StudentWHERE College.cName =

Apply.cNameAND Apply.sID =

Student.sIDAND GPA >= ALL (SELECT GPAFROM Student, ApplyWHERE Student.sID =


College.cName )) AS GPAFROM College;

SQL

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SELECT cName, state,( SELECT DISTINCT GPAFROM Apply, StudentWHERE College.cName =


Student.sIDAND GPA >= ALL (SELECT GPAFROM Student, ApplyWHERE Student.sID =


College.cName )) AS GPAFROM College;

Result

SQL

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SELECT cName, state( SELECT DISTINCT sNameFROM Apply, StudentWHERE College.cName =


Student.sID ) AS sName

FROM College;

SQL

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SELECT cName, state( SELECT DISTINCT sNameFROM Apply, StudentWHERE College.cName =


Student.sID ) AS sName

FROM College;

Result

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Aggregation

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“Aggregation” functionsover values in multiple rows:min, max, sum, avg, count

Aggregation




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SELECT A1,A2,…,AnFROM R1,R2, …,RmWHERE conditionGROUP BY columnsHAVING condition

“Aggregation” functionsover values in multiple rows:min, max, sum, avg, count

New clauses

SQL

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SELECT * FROM Student;

SELECT AVG(GPA) FROM Student;

SQL

Result Result

SQL

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SELECT *FROM Student, ApplyWHERE Student.sID =


SELECT MIN(GPA)FROM Student, ApplyWHERE Student.sID =


SQL

Result Result

SQL

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SELECT *FROM Student, ApplyWHERE Student.sID =


SELECT AVG(GPA)FROM Student, ApplyWHERE Student.sID =


SQL

Result Result

SQL

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SELECT *FROM StudentWHERE sID IN( SELECT sIDFROM ApplyWHERE major = 'CS'

);

SELECT AVG(GPA)FROM StudentWHERE sID IN( SELECT sIDFROM ApplyWHERE major = 'CS'

);

SQL

Result Result

SQL

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SELECT *FROM CollegeWHERE enrollment > 15000;

SELECT COUNT(*)FROM CollegeWHERE enrollment > 15000;

SQL

Result Result

SQL

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SELECT COUNT(*)FROM ApplyWHERE cName = 'Cornell';

SELECT COUNT(DISTINCT sID)FROM ApplyWHERE cName = 'Cornell';

SQL

Result Result

SQL

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SELECT sIDFROM ApplyWHERE cName = 'Cornell';

Result

SQL

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SELECT *FROM Student S1WHERE( SELECT COUNT(*)FROM Student S2WHERE S2.sID <> S1.sIDAND S2.GPA = S1.GPA

) = ( SELECT COUNT(*)FROM Student S2WHERE S2.sID <> S1.sIDAND S2.sizeHS = S1.sizeHS

);

Result

SQL

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SELECT CS.avgGPA - NonCS.avgGPAFROM(SELECT AVG(GPA) AS avgGPAFROM StudentWHERE sID IN(SELECT sIDFROM ApplyWHERE major = 'CS')) CS,

(SELECT AVG(GPA) AS avgGPAFROM StudentWHERE sID NOT IN(SELECT sIDFROM ApplyWHERE major = 'CS')) nonCS;

SQL

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SELECT CS.avgGPA - NonCS.avgGPAFROM(SELECT AVG(GPA) AS avgGPAFROM StudentWHERE sID IN(SELECT sIDFROM ApplyWHERE major = 'CS')) CS,

(SELECT AVG(GPA) AS avgGPAFROM StudentWHERE sID NOT IN(SELECT sIDFROM ApplyWHERE major = 'CS')) nonCS;

Result

SQL

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SELECT( SELECT AVG(GPA) AS avgGPAFROM StudentWHERE sID IN( SELECT sIDFROM ApplyWHERE major = 'CS' ) ) -

( SELECT AVG(GPA) AS avgGPAFROM StudentWHERE sID NOT IN( SELECT sIDFROM ApplyWHERE major = 'CS' ) ) D

FROM Student;

Result

SQL

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SELECT DISTINCT( SELECT AVG(GPA) AS avgGPAFROM StudentWHERE sID IN( SELECT sIDFROM ApplyWHERE major = 'CS' ) ) -

( SELECT AVG(GPA) AS avgGPAFROM StudentWHERE sID NOT IN( SELECT sIDFROM ApplyWHERE major = 'CS' ) ) D

FROM Student;

Result

SQL

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SELECT cName, COUNT(*)FROM ApplyGROUP BY cName;

Result

SQL

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SELECT *FROM ApplyORDER BY cName;

Result

SQL

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SELECT cName, COUNT(*)FROM ApplyGROUP BY cName;

Result

SQL

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SELECT state, SUM(enrollment)FROM CollegeGROUP BY state;

Result

SQL

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SELECT cName, major, MIN(GPA), MAX(GPA)


Apply.sIDGROUP BY cName, major;

SQL

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SELECT cName, major, GPAFROM Student, ApplyWHERE Student.sID =

Apply.sIDORDER BY cName, major;

Result

SQL

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SELECT cName, major, MIN(GPA), MAX(GPA)


Apply.sIDGROUP BY cName, major;

Result

SQL

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SELECT MAX(mx-mn)FROM( SELECT cName, major,

MIN(GPA) AS mn, MAX(GPA) AS mx


Apply.sIDGROUP BY cName, major

) M;

Result

SQL

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SELECT Student.sID, COUNT(DISTINCT cName)


Apply.sIDGROUP BY Student.sID;

SQL

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SELECT Student.sID, cNameFROM Student, ApplyWHERE Student.sID =

Apply.sIDORDER BY Student.sID;

Result

SQL

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Apply.sIDGROUP BY Student.sID;

Result

SQL

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Apply.sIDGROUP BY Student.sIDUNIONSELECT sID, 0FROM StudentWHERE sID NOT IN( SELECT sID FROM Apply );

SQL

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Apply.sIDGROUP BY Student.sIDUNIONSELECT sID, 0FROM StudentWHERE sID NOT IN( SELECT sID FROM Apply );

Result

SQL

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SELECT cNameFROM ApplyGROUP BY cNameHAVING COUNT(*) < 5;

SQL

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Result

SQL

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SELECT cNameFROM Apply A1WHERE 5 >(SELECT COUNT(*)FROM Apply A2WHERE A2.cName = A1.cName

);

Result

SQL

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SELECT DISTINCT cNameFROM Apply A1WHERE 5 >(SELECT COUNT(*)FROM Apply A2WHERE A2.cName = A1.cName

);

Result

SQL

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SELECT cNameFROM ApplyGROUP BY cNameHAVING COUNT(DISTINCT sID) < 5;

Result

SQL


Result

SQL

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SELECT majorFROM Student, ApplyWHERE Student.sID =

Apply.sIDGROUP BY majorHAVING MAX(GPA) < ( SELECT AVG(GPA) FROM Student );

SQL

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SELECT majorFROM Student, ApplyWHERE Student.sID =

Apply.sIDGROUP BY majorHAVING MAX(GPA) < ( SELECT AVG(GPA) FROM Student );

Result

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NULL Values




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NULL values: undefined or unknown

SQL

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SELECT *FROM Student;

Result

SQL

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INSERT INTO Student VALUES (432, 'Kevin', null, 1500);INSERT INTO Student VALUES (321, 'Lori', null, 2500);

Result

SQL

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SELECT sID, sName, GPAFROM StudentWHERE GPA > 3.5;

Result

SQL

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SELECT sID, sName, GPAFROM StudentWHERE GPA <= 3.5;

Result

SQL

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SELECT sID, sName, GPAFROM StudentWHERE GPA > 3.5 OR

GPA <= 3.5;

Result

SQL

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SELECT sID, sName, GPAFROM StudentWHERE GPA > 3.5 OR

GPA <= 3.5 ORGPA IS NULL;

Result

SQL

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SELECT sID, sName, GPA, sizeHS

FROM StudentWHERE GPA > 3.5 OR

sizeHS < 1600;

Result

SQL

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SELECT sID, sName, GPA, sizeHS

FROM StudentWHERE GPA > 3.5 OR

sizeHS < 1600 ORsizeHS >= 1600;

Result

SQL

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SELECT COUNT(*)FROM StudentWHERE GPA IS NOT NULL;

Result

SQL

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SELECT COUNT(DISTINCT GPA)FROM StudentWHERE GPA IS NOT NULL;

Result

SQL

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SELECT DISTINCT GPAFROM Student;

Result

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Data Modification Statements

• Inserting new data (2 methods)

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INSERT INTO TABLEVALUES (A1,A2,…,An)

INSERT INTO TABLESelect-Statement


• Deleting existing data

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DELETE FROM TABLEWHERE Condition


• Updating existing data

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UPDATE TABLESET Attribute = ExpressionWHERE Condition


• Updating existing data




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UPDATE TABLESET A1 = Expr1, A2 = Expr2, …,

A3 = Expr3, WHERE Condition

SQL

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INSERT INTO CollegeVALUES ('Carnegie Mellon',

'PA', 11500);

Result

SELECT * FROM College;

SQL

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SELECT *FROM StudentWHERE sID NOT IN(SELECT sIDFROM Apply

);

Result

SQL

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SELECT sID, 'Carnegie Mellon', 'CS', NULL

FROM StudentWHERE sID NOT IN(SELECT sIDFROM Apply

);

Result

SQL

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INSERT INTO ApplySELECT sID, 'Carnegie Mellon’,

‘CS’, NULLFROM StudentWHERE sID NOT IN(SELECT sIDFROM Apply

);

Result

SELECT * FROM Apply;

SQL

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SELECT *FROM StudentWHERE sID IN(SELECT sIDFROM ApplyWHERE major = ‘EE’AND decision = ‘N’

);

Result

SQL

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SELECT sID, 'Carnegie Mellon','EE', 'Y'

FROM StudentWHERE sID IN(SELECT sIDFROM ApplyWHERE major = ‘EE’AND decision = ‘N’

);

Result

SQL

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INSERT INTO ApplySELECT sID, 'Carnegie Mellon',

'EE', 'Y'FROM StudentWHERE sID IN(SELECT sIDFROM ApplyWHERE major = ‘EE’AND decision = ‘N’

);

Result


SQL

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SELECT sID, COUNT(DISTINCT major)

FROM ApplyGROUP BY sIDHAVING COUNT(DISTINCT major)

> 2;

Result

SQL

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DELETEFROM StudentWHERE sID IN(SELECT sIDFROM ApplyGROUP BY sIDHAVING COUNT(DISTINCT major)

> 2);

Result


SQL

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DELETEFROM ApplyWHERE sID IN(SELECT sIDFROM ApplyGROUP BY sIDHAVING COUNT(DISTINCT major)

> 2);

Result


SQL

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SELECT *FROM CollegeWHERE cName NOT IN(SELECT cNameFROM ApplyWHERE major = 'CS'

);

Result

SQL

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DELETEFROM CollegeWHERE cName NOT IN(SELECT cNameFROM ApplyWHERE major = 'CS'

);

Result

SELECT * FROM College;

SQL

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SELECT *FROM ApplyWHERE cName =

'Carnegie Mellon'AND sID IN

(SELECT sIDFROM StudentWHERE GPA < 3.6

);

Result

SQL

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UPDATE ApplySET decision = ‘Y’,

major = ‘economics’WHERE cName =

'Carnegie Mellon'AND sID IN

(SELECT sIDFROM StudentWHERE GPA < 3.6

);

Result

SQL

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SELECT *FROM ApplyWHERE major = 'EE'AND sID IN

( SELECT sIDFROM StudentWHERE GPA >= ALL( SELECT GPAFROM StudentWHERE sID IN( SELECT sIDFROM ApplyWHERE major = 'EE‘

))

);

Result

SQL

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UPDATE ApplySET major = 'CSE'WHERE major = 'EE'AND sID IN

( SELECT sIDFROM StudentWHERE GPA >= ALL( SELECT GPAFROM StudentWHERE sID IN( SELECT sIDFROM ApplyWHERE major = 'EE‘

))

);

Result

SQL

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UPDATE StudentSETGPA = ( SELECT MAX(GPA)

FROM Student ),sizeHS = ( SELECT MIN(sizeHS)

FROM Student );

Result


SQL

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UPDATE ApplySET decision = 'Y';

Result


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JOIN Operators

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Explicit Join of tables

JOIN Operators

• Inner Join On Condition

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⋈Θ

JOIN Operators


• Natural Join

SQL - Suan Lee 196



⋈

⋈Θ

JOIN Operators


• Natural Join

• Inner Join Using(attributes)

SQL - Suan Lee 197



⋈

⋈Θ

⋈

JOIN Operators


• Natural Join

• Inner Join Using(attributes)

• Left | Right | Full Outer Join

SQL - Suan Lee 198



⋈

⋈Θ

⋈

SQL

SQL - Suan Lee 199

SELECT DISTINCT sName, majorFROM Student, ApplyWHERE Student.sID = Apply.sID;

Result

SQL

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SELECT DISTINCT sName, majorFROM Student INNER JOIN ApplyON Student.sID = Apply.sID;

Result

SQL

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SELECT DISTINCT sName, majorFROM Student JOIN ApplyON Student.sID = Apply.sID;

Result

SQL

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SELECT sName, GPAFROM Student, ApplyWHERE Student.sID = Apply.sIDAND sizeHS < 1000AND major = 'CS'AND cName = 'Stanford';

Result

SQL

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SELECT sName, GPAFROM Student JOIN ApplyON Student.sID = Apply.sIDWHERE sizeHS < 1000AND major = 'CS'AND cName = 'Stanford';

Result

SQL

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SELECT sName, GPAFROM Student JOIN ApplyON Student.sID = Apply.sIDAND sizeHS < 1000AND major = 'CS'AND cName = 'Stanford';

Result

SQL

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Result

SQL

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SELECT Apply.sID, sName, GPA, Apply.cName, enrollment

FROM Apply, Student, CollegeWHERE Apply.sID = Student.sIDAND Apply.cName =

College.cName;

Result

SQL

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FROM Apply JOIN Student JOIN College

ON Apply.sID = Student.sIDAND Apply.cName =

College.cName;

Result

SQL

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FROM (Apply JOIN Student ONApply.sID = Student.sID)

JOIN CollegeON Apply.cName =

College.cName;

SQL

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FROM (Apply JOIN Student ONApply.sID = Student.sID)

JOIN CollegeON Apply.cName =

College.cName;

Result

SQL

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SELECT DISTINCT sName, majorFROM Student INNER JOIN ApplyON Student.sID = Apply.sID;

Result

SQL

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SELECT DISTINCT sName, majorFROM StudentNATURAL JOIN Apply;

Result

SQL

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SELECT *FROM StudentNATURAL JOIN Apply;

Result

SQL

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SELECT DISTINCT sIDFROM StudentNATURAL JOIN Apply;

Result

SQL

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SELECT DISTINCT sIDFROM Student, Apply;

Result

SQL

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Result

SQL

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SELECT sName, GPAFROM StudentNATURAL JOIN ApplyWHERE sizeHS < 1000AND major = 'CS'AND cName = 'Stanford';

Result

SQL

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SELECT sName, GPAFROM StudentJOIN Apply USING(sID)WHERE sizeHS < 1000AND major = 'CS'AND cName = 'Stanford';

SQL

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SELECT sName, GPAFROM StudentJOIN Apply USING(sID)WHERE sizeHS < 1000AND major = 'CS'AND cName = 'Stanford';

Result

SQL

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SELECT *FROM Student S1 NATURAL JOIN Student S2;

Result

SQL

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SELECT *FROM Student;

Result

SQL

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SELECT sName, sID, cName, majorFROM StudentINNER JOIN Apply USING(sID);

Result

SQL

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SELECT sName, sID, cName, majorFROM StudentOUTER JOIN Apply USING(sID);

Result

SQL

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SELECT sName, sID, cName, majorFROM StudentLEFT OUTER JOIN Apply USING(sID);

Result

SQL

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SELECT sName, sID, cName, majorFROM StudentLEFT JOIN Apply USING(sID);

Result

SQL

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SELECT sName, sID, cName, majorFROM StudentNATURAL LEFT OUTER JOIN Apply;

Result

SQL

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SELECT sName, Student.sID, cName, major

FROM Student, ApplyWHERE Student.sID = Apply.sIDUNIONSELECT sName, sID, NULL, NULLFROM StudentWHERE sID NOT IN( SELECT sID FROM Apply );

Result

SQL

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SELECT sName, sID, cName, majorFROM StudentNATURAL LEFT OUTER JOIN Apply;

Result

SQL

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INSERT INTO Apply VALUES (321, 'MIT', 'history', 'N');INSERT INTO Apply VALUES (321, 'MIT', 'psychology', 'Y');

SQL

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SELECT sName, sID, cName, majorFROM ApplyNATURAL LEFT OUTER JOIN Student;

Result

SQL

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SELECT sName, sID, cName, majorFROM StudentNATURAL RIGHT OUTER JOIN Apply;

Result

SQL

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SELECT sName, sID, cName, majorFROM StudentFULL OUTER JOIN Apply USING(sID);

Result

SQL

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SELECT sName, sID, cName, majorFROM StudentLEFT OUTER JOIN Apply USING(sID)UNIONSELECT sName, sID, cName, majorFROM StudentRIGHT OUTER JOIN Apply USING(sID)

Result

SQL

SQL - Suan Lee 233

SELECT sName, Student.sID, cName, major

FROM Student, ApplyWHERE Student.sID = Apply.sIDUNIONSELECT sName, sID, NULL, NULLFROM StudentWHERE sID NOT IN ( SELECT sID FROM Apply )UNIONSELECT NULL, sID, cName, majorFROM ApplyWHERE sID NOT IN( SELECT sID FROM Student );

Result

SQL - Suan Lee 234

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