关于字符串相加的有关问题：由于null加上任何字符串都为null

(case when A.ItemMemo is null then '' else A.ItemMemo end)     +                  (case when A4.Description is null then '' else A4.Description end)    AS 工艺要求

isnull(A.ItemMemo,'')+isnull(A4.Description,'') as 工艺要求
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SQL code
isnull(A.ItemMemo,'')+isnull(A4.Description,'') as 工艺要求

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SQL code
isnull(A.ItemMemo,'')+isnull(A4.Description,'') AS 工艺要求