Question

如何简化以下SQL查询，

DECLARE @EMPLOYEE1 TABLE (EMPID INT,DEPT1 INT,DEPT2 INT)
DECLARE @EMPLOYEE2 TABLE (EMPID INT,DEPT1 INT,DEPT2 INT)

    INSERT INTO @EMPLOYEE1 VALUES
    (1,1,1),
    (2,2,2),
    (3,10,3),
    (4,4,4)
    INSERT INTO @EMPLOYEE2 VALUES
    (1,1,1),
    (2,2,2),
    (3,10,10),
    (4,10,4)       

    SELECT  A.EMPID,    
            A.DEPT1 EMP1_DEPT,
            0 TYPES
    FROM    @EMPLOYEE1 A
    LEFT JOIN @EMPLOYEE2 B ON A.DEPT1=B.DEPT1
    WHERE   B.DEPT1 IS NULL 

    UNION ALL

    SELECT  A.EMPID,    
            A.DEPT2 EMP2_DEPT,
            1 TYPES
    FROM    @EMPLOYEE1 A
    LEFT JOIN @EMPLOYEE2 B ON A.DEPT2=B.DEPT2
    WHERE   B.DEPT2 IS NULL

任何人都可以解决这个问题，谢谢你提前

Answer 1

这是一种方法：

Template.dash_board_content1.helpers({

    'userTerritory': function(){
        const territoryList = Template.instance().state.get('userTerritoryList');

        if (territoryList) return territoryList;

        Meteor.call('userTerritoryList', function(error,result){
            if(!error){
                Template.instance().state.set('userTerritoryList', result);
            } else {
                const errs = Template.instance().state.get('errors');
                errs.push(error);
                //update errors
                Template.instance().state.set('errors', errs);
            }
        });
    },

    'getErrors' : function() {
        //use in your template to display multiple err messages
        return  Template.instance().state.get('errors');
    },
});

Answer 2

以下是使用CROSS APPLY和VALUES的另一种选择：

SELECT A.EMPID,
       A_D.DEPT AS 'EMP1_DEPT',
       A_D.[TYPES]
FROM @EMPLOYEE1 A
CROSS APPLY (VALUES (A.DEPT1, 0), (A.DEPT2, 1)) A_D ( DEPT, [TYPES] )
WHERE NOT EXISTS (SELECT 1
                  FROM @EMPLOYEE2 B
                  CROSS APPLY (VALUES (B.DEPT1, 0), (B.DEPT2, 1)) B_D ( DEPT, [TYPES] )
                  WHERE B_D.DEPT = A_D.DEPT
                    AND B_D.[TYPES] = A_D.[TYPES]);

这种方法的优点是每个表只被击中一次。它使用NOT EXISTS通过使用Left Anti Semi Join来提高查询计划的性能。

如何简化以下SQL查询？

2 个答案: