无敌CASE

/*选择及WHERE条件中的CASE*/

SELECT
    CASE
        WHEN 0 = 0
        THEN 0

        WHEN 1 = 1
        THEN 1
        
        ELSE
            NULL
    END AS case_col
/*
FROM
    tb_beyond
*/
WHERE
    CASE
        WHEN 0 = 0
        THEN 'A' = 'A'

        WHEN 1 = 1
        THEN 'B' = 'B'

        ELSE
            0 = 1
    END



/*更新中的CASE*/
UPDATE
    t_beyond
SET
    member_count =
        CASE
            WHEN year_month <= 19930630
            THEN 4
            WHEN year_mont > 19830630
            THEN 3
            ELSE 5
        END,
    leader = '黄家驹'
FROM
    t_beyond_base