如何通过CASE语句将空值更改为“0”

Question

我坚持将空值更改为“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

结果仍为null

StarID
5
NULL

Answer 1

使用IsNull

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