Question

我的查询创建排名系统时遇到了一些麻烦。我的查询很好，但我使用了一些变量，结果不一致。

第一个案例陈述是好的，但不是第二个。我是否有可能在没有使用变量的情况下进行第二次计算？

        CASE
            WHEN SUM(pso.total_products_wt)/COUNT(pso.total_products_wt) BETWEEN 0 AND 100 AND DATEDIFF(NOW(),MAX(pso.date_add))        BETWEEN 0 AND 50        THEN @scoring := ROUND(50 + SUM(pso.total_products_wt)/COUNT(pso.total_products_wt) + COUNT(pso.id_order)*10,0)
            WHEN SUM(pso.total_products_wt)/COUNT(pso.total_products_wt) BETWEEN 0 AND 100 AND DATEDIFF(NOW(),MAX(pso.date_add))        BETWEEN 51 AND 150      THEN @scoring := ROUND(20 + SUM(pso.total_products_wt)/COUNT(pso.total_products_wt) + COUNT(pso.id_order)*10,0)
            WHEN SUM(pso.total_products_wt)/COUNT(pso.total_products_wt) BETWEEN 0 AND 100 AND DATEDIFF(NOW(),MAX(pso.date_add))        BETWEEN 151 AND 364     THEN @scoring := ROUND(SUM(pso.total_products_wt)/COUNT(pso.total_products_wt) + COUNT(pso.id_order)*10,0)
            WHEN SUM(pso.total_products_wt)/COUNT(pso.total_products_wt) BETWEEN 0 AND 100 AND DATEDIFF(NOW(),MAX(pso.date_add))        >= 365                  THEN @scoring := ROUND(SUM(pso.total_products_wt)/COUNT(pso.total_products_wt)/20 + COUNT(pso.id_order)*10,0)
            WHEN SUM(pso.total_products_wt)/COUNT(pso.total_products_wt) BETWEEN 101 AND 499 AND DATEDIFF(NOW(),MAX(pso.date_add))      BETWEEN 0 AND 50        THEN @scoring := ROUND(50 + SUM(pso.total_products_wt)/COUNT(pso.total_products_wt)/3 + COUNT(pso.id_order)*10,0)
            WHEN SUM(pso.total_products_wt)/COUNT(pso.total_products_wt) BETWEEN 101 AND 499 AND DATEDIFF(NOW(),MAX(pso.date_add))      BETWEEN 51 AND 150      THEN @scoring := ROUND(20 + SUM(pso.total_products_wt)/COUNT(pso.total_products_wt)/3 + COUNT(pso.id_order)*10,0)
            WHEN SUM(pso.total_products_wt)/COUNT(pso.total_products_wt) BETWEEN 101 AND 499 AND DATEDIFF(NOW(),MAX(pso.date_add))      BETWEEN 151 AND 364     THEN @scoring := ROUND(SUM(pso.total_products_wt)/COUNT(pso.total_products_wt)/3 + COUNT(pso.id_order)*10,0)
            WHEN SUM(pso.total_products_wt)/COUNT(pso.total_products_wt) BETWEEN 101 AND 499 AND DATEDIFF(NOW(),MAX(pso.date_add))      >= 365                  THEN @scoring := ROUND(SUM(pso.total_products_wt)/COUNT(pso.total_products_wt)/20 + COUNT(pso.id_order)*10,0)
            WHEN SUM(pso.total_products_wt)/COUNT(pso.total_products_wt) >= 500 AND DATEDIFF(NOW(),MAX(pso.date_add))                   BETWEEN 0 AND 50        THEN @scoring := ROUND(50 + SUM(pso.total_products_wt)/COUNT(pso.total_products_wt)/5 + COUNT(pso.id_order)*10,0)
            WHEN SUM(pso.total_products_wt)/COUNT(pso.total_products_wt) >= 500 AND DATEDIFF(NOW(),MAX(pso.date_add))                   BETWEEN 51 AND 150      THEN @scoring := ROUND(20 + SUM(pso.total_products_wt)/COUNT(pso.total_products_wt)/5 + COUNT(pso.id_order)*10,0)
            WHEN SUM(pso.total_products_wt)/COUNT(pso.total_products_wt) >= 500 AND DATEDIFF(NOW(),MAX(pso.date_add))                   BETWEEN 151 AND 364     THEN @scoring := ROUND(SUM(pso.total_products_wt)/COUNT(pso.total_products_wt)/5 + COUNT(pso.id_order)*10,0)
            WHEN SUM(pso.total_products_wt)/COUNT(pso.total_products_wt) >= 500 AND DATEDIFF(NOW(),MAX(pso.date_add))                   >= 365                  THEN @scoring := ROUND(SUM(pso.total_products_wt)/COUNT(pso.total_products_wt)/20 + COUNT(pso.id_order)*10,0)
        END AS 'Scoring',
        CASE
            WHEN @scoring >= 200 THEN '5/5'
            WHEN @scoring BETWEEN 150 AND 199 THEN '4/5'
            WHEN @scoring BETWEEN 100 AND 149 THEN '3/5'
            WHEN @scoring BETWEEN 50 AND 99 THEN '2/5'
            WHEN @scoring <= 49 THEN '1/5'
        END AS 'Rank'

Answer 1

来自文档https://dev.mysql.com/doc/refman/5.5/en/user-variables.html：

但是，涉及用户变量的表达式的评估顺序是未定义的。

所以在你的第二个表达式中，你可以在第一个表达式（正如你所期望的）修改之后读取变量Infinity对，或者恰好之前。

解决方案：

@scoring

在SQL中创建排名系统，变量问题

1 个答案: