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Subqueries and JoinPrepared by: Engr. Lance Adrian A. Valdez

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Intended Learning Outcome

Learn to write queries with subqueries. Learn to select columns rom multiple tables wit

Learn to select records rom multiple tables with

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SubqueriesSubqueries are queries embedded in queries. "hey areretrie#e data rom one table based on data in another ta

generally are used when tables ha#e some $ind o relatioe&ample' in the (orthwind database' the )rders tab*ustomer +, -eld' which reerences a customer in the *table. etrie#ing the *ustomer +, or a speci-c order straightorward.

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SubqueriesSample*odes:

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SubqueriesSample*ode:

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JoinsJoins return data from multiple tables.

Types of SQL Joins

1. Inner Join

2. Left Join

3. Right Join

. !ull Join "!ull #uter Join$

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Joins (Inner Join)

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Joins (Inner Join)Sample*odes:

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Table Aliases/sing ull table names as pre-&es can ma$e S0Lunnecessarily wordy. "able aliases can ma$e the code a l

concise. "he e&ample below' which is identical in unctithe query abo#e' illustrates the use o table aliases.

An alias can be called whate#er you want. "hough typica-rst letter2s3 o the table name' it can be whate#er ma$esyou as the ,e#eloper. %or e&ample' the alias or a tabCourses

can bec' or

crs' or

debbie' etc.

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Table AliasesSample*ode:

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Multi-table Joins

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Multi-table JoinsSample*ode:

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Joins (Left Join)

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Joins (Left Join)Sample*ode:

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Joins (Right Join)

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Joins (Right Join)Sample*ode:

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Joins (ull Join)

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Joins (ull Join)Sample*ode: