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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 $ind o relatioe&le' in the (orthwind database' the )rders tab*ustomer +, -eld' which reerences a customer in the *table. etrie#ing the *ustomer +, or a speci-c order straightorward.
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SubqueriesSample*odes:
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SubqueriesSample*ode:
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JoinsJoins return data from multiple tables.
Types of SQL Joins
1. Inner Join
2. Left Join
3. Right Join
. !ull Join "!ull #uter Join$
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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&le 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&le' 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: