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  • SQL IN

    here are some additional clause in the SQL language that can be used to simplify queries by decrease the use of the single Operator repeatly. One of them is IN clause.

    IN clause is used to simplify the queries if you want to select data that meet a large number of options. That means IN function helps reduce the need to use multiple OR conditions.

    The SQL syntax for the IN operator is:

    SELECT [COLUMN NAME] FROM [TABLE NAME]
    WHERE [COLUMN] IN ( [VALUE LIST] )


    EXAMPLE :

    We would like to display all information in IT Department OR Marketing.

    Table GameScores

    PlayerName Department Scores
    Jason IT 3000
    Irene IT 1500
    Jane Marketing 1000
    David Marketing 2500
    Paul HR 2000
    James HR 2000

    SQL statement :

    SELECT * FROM GameScores
    WHERE Department IN ('IT','Marketing')

    Result:

    PlayerName Department Scores
    Jason IT 3000
    Irene IT 1500
    Jane Marketing 1000
    David Marketing 2500

    Actually, This SQL statement below also can show the same results.

    SELECT * FROM GameScores
    WHERE
    Department ='IT' OR Department ='Marketing'

    Why we should use IN clause?
    We should use IN comparisons instead of mutiple comparisons linked using OR whenever possible in order to improve maintainability of our queries. Adding additional value to an IN clause is much easier than repeatly the OR clauses. The code also easier to read as well.

     

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  • 原文地址:https://www.cnblogs.com/zhoug2020/p/3328298.html
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