• EXISTS


    IF OBJECT_ID('tempdb..#Students') IS NOT NULL
    	BEGIN
    		DROP TABLE #Students;
    	END
    CREATE TABLE #Students
    (
    	[Id] BIGINT NOT NULL,
    	[Name] VARCHAR(MAX) NOT NULL,
    	[Gender] VARCHAR(MAX) NULL,
    )
    INSERT INTO #Students VALUES(1,'Lucio','man')
    INSERT INTO #Students VALUES(2,'Lisa','woman')
    INSERT INTO #Students VALUES(3,'Michael','man')
    INSERT INTO #Students VALUES(4,'Vic','man')
    INSERT INTO #Students VALUES(5,'June','woman')
    INSERT INTO #Students VALUES(6,'Lillian','woman')
    INSERT INTO #Students VALUES(7,'Jane','woman')
    INSERT INTO #Students VALUES(8,'Walter','man')
    INSERT INTO #Students VALUES(9,'Jesse','man')
    
    SELECT * FROM #Students
    
    Id	Name	Gender
    ------- ------- --------
    1	Lucio	man
    2	Lisa	woman
    3	Michael	man
    4	Vic	man
    5	June	woman
    6	Lillian	woman
    7	Jane	woman
    8	Walter	man
    9	Jesse	man
    
    IF OBJECT_ID('tempdb..#Scores') IS NOT NULL
    	BEGIN
    		DROP TABLE #Scores;
    	END
    CREATE TABLE #Scores
    (
    	[StudentId] BIGINT NOT NULL,
    	[Score] INT NOT NULL,
    )
    INSERT INTO #Scores VALUES(1,100)
    INSERT INTO #Scores VALUES(2,60)
    INSERT INTO #Scores VALUES(3,80)
    INSERT INTO #Scores VALUES(4,80)
    INSERT INTO #Scores VALUES(5,90)
    INSERT INTO #Scores VALUES(6,80)
    INSERT INTO #Scores VALUES(7,60)
    INSERT INTO #Scores VALUES(8,80)
    INSERT INTO #Scores VALUES(9,70)
    
    SELECT * FROM #Scores
    
    StudentId	Score
    --------------- --------
    1	        100
    2	        60
    3	        80
    4	        80
    5	        90
    6	        80
    7	        60
    8	        80
    9	        70
    

    使用 IN 和 EXISTS

    SELECT * FROM #Students WHERE Id IN (SELECT StudentId FROM #Scores WHERE Score >= 90)
    SELECT * FROM #Students A WHERE EXISTS (SELECT * FROM #Scores B WHERE Score >= 90 AND A.Id = B.StudentId)
    SELECT * FROM #Students A WHERE Id = ANY (SELECT StudentId FROM #Scores WHERE Score >= 90)
    
    Id	Name	Gender
    ------- ------- -------
    1	Lucio	man
    5	June	woman
    
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  • 原文地址:https://www.cnblogs.com/luciolu/p/15818469.html
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