SQL - 計算具有相同值的行數而不顯示計數

Question

如何計算 Selected 表中具有相同a.customer值的行數，但我不想顯示 Count，只是顯示 Selected 行並將顯示限制為 Count 中的前 3 個。 我有這樣的代碼：

    SELECT a.number, b.product, 
    x.descp, b.serial, a.customer
    FROM a 
    LEFT JOIN b
    ON a.number = b.number
    LEFT JOIN x
    ON b.product = x.product
    LEFT JOIN d
    ON a.stat = d.stat
    WHERE d.prmt = 'ABC'
    AND a.date >= 20210528
    AND a.date <= 20210530

Answer 1

您需要將計數和 ROW_NUMBER（僅在較新版本中可用）添加到孔 select

SELECT a.number, b.product, 
    x.descp, b.serial, a.customer
    FROM a 
    INNER JOIN (SELECT 
    a.customer, COUNT(*) countr, ROW_NUMBER() OVER( ORDER BY COUNT(*) DESC) rn
FROM
    a
        LEFT JOIN
    b ON a.number = b.number
        LEFT JOIN
    x ON b.product = x.product
        LEFT JOIN
    d ON a.stat = d.stat
WHERE
    d.prmt = 'ABC' AND a.date >= 20210528
        AND a.date <= 20210530
GROUP BY a.customer) t1 ON t1.customer = a.customer
    LEFT JOIN b
    ON a.number = b.number
    LEFT JOIN x
    ON b.product = x.product
    LEFT JOIN d
    ON a.stat = d.stat
    WHERE d.prmt = 'ABC'
    AND a.date >= 20210528
    AND a.date <= 20210530
    AND rn <= 3