Question

MySQL Case语句错误：

当我使用以下内容时，作为单独的情况，查询有效，但是当它们组合时它们不会。

我正在使用MySQL Workbench

错误：
仅返回制造商信息，而不是基于ProdID的查询 ProdID是正确的，我用它在此之前提取ID并返回正确的ID＃。

我在1列中要求它们在下一步中运行计算。

不工作：

CASE 
    When(T4.manufacturers_id = 1) then ''
    When(T4.manufacturers_id = 2) then '.10'
    When(T4.manufacturers_id = 3) then '.10'
    When(T4.manufacturers_id = 4) then '0'
    When(T3.products_id = 11) then '.10'
    When(T3.products_id = 34) then '.10'
    When(T3.products_id = 35) then '.10'
    When(T3.products_id = 36) then '.10'
    When(T3.products_id = 37) then '.10'
    When(T3.products_id = 38) then '.10'
    When(T3.products_id = 39) then '.10'
end As Comms,

工作：

CASE 
    When(T4.manufacturers_id = 1) then ''
    When(T4.manufacturers_id = 2) then '.10'
    When(T4.manufacturers_id = 3) then '.10'
    When(T4.manufacturers_id = 4) then '0'
end As MIDComms,

case
    When(T3.products_id = 11) then '.10'
    When(T3.products_id = 34) then '.10'
    When(T3.products_id = 35) then '.10'
    When(T3.products_id = 36) then '.10'
    When(T3.products_id = 37) then '.10'
    When(T3.products_id = 38) then '.10'
    When(T3.products_id = 39) then '.10'
end As PIDComms,

理想情况下，我希望：

    CASE 
    When(T4.manufacturers_id = 1) then ''
    When(T4.manufacturers_id = 2) then '.10'
    When(T4.manufacturers_id = 3) then '.10'
    When(T4.manufacturers_id = 4) then '0'
    When(T3.products_id = 11) then '.10'
    When(T3.products_id) between 34 and 39 then '.10'
end As Comms,

提前致谢

Answer 1

case语句只返回一个值 - 遇到的第一个值。也许你想要某种连接：

CONCAT_WS(':',
          (CASE When(T4.manufacturers_id = 1) then ''
                When(T4.manufacturers_id = 2) then '.10'
                When(T4.manufacturers_id = 3) then '.10'
                When(T4.manufacturers_id = 4) then '0'
           END),
          (CASE When(T3.products_id = 11) then '.10'
                When(T3.products_id = 34) then '.10'
                When(T3.products_id = 35) then '.10'
                When(T3.products_id = 36) then '.10'
                When(T3.products_id = 37) then '.10'
                When(T3.products_id = 38) then '.10'
                When(T3.products_id = 39) then '.10'
           end) ) As Comms,

MySQL case语句错误，数据未显示部分查询

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