Sql server 2008 r2 如何将空值更改为“0”；0“；逐案陈述

我不得不将空值改为“0”，我写了这样的代码

SELECT 
  Custom.tblR_docProducer.libtxtDocumentID AS ParentID, 
  Custom.tblR_docProducer_grdProductRating.grdProductName AS ProductName, 
  Custom.tblR_docProducer_grdProductRating.grdProductType AS CategoryID,
  Custom.tblR_docProducer_grdProductRating.gdlkRating AS StarID, 
  Custom.tblR_docProducer_grdProductRating.gdlkRatingYear AS YearID, 
  1 AS DisplayOrder, 
  0 AS isDisabled
FROM Custom.tblR_docProducer 
INNER JOIN Custom.tblR_docProducer_grdProductRating 
  ON Custom.tblR_docProducer.Id = Custom.tblR_docProducer_grdProductRating._Parent

StarID
5
NULL

结果仍然是空的，如下所示

SELECT 
  Custom.tblR_docProducer.libtxtDocumentID AS ParentID, 
  Custom.tblR_docProducer_grdProductRating.grdProductName AS ProductName, 
  Custom.tblR_docProducer_grdProductRating.grdProductType AS CategoryID,
  Custom.tblR_docProducer_grdProductRating.gdlkRating AS StarID, 
  Custom.tblR_docProducer_grdProductRating.gdlkRatingYear AS YearID, 
  1 AS DisplayOrder, 
  0 AS isDisabled
FROM Custom.tblR_docProducer 
INNER JOIN Custom.tblR_docProducer_grdProductRating 
  ON Custom.tblR_docProducer.Id = Custom.tblR_docProducer_grdProductRating._Parent

StarID
5
NULL

使用IsNull

IsNull(Custom.tblR_docProducer_grdProductRating.gdlkRating, 0) AS StarID

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虽然不能完全理解结果，但可以使用ISNULL（）函数包装列。e、 g.ISNULL（MyColumn，0）作为MyColumn您永远不会将NULL更改为0，并且查询中也没有标题所建议的任何case语句。