将空数据复制到列中的非空值

Question

我想将一些旧列中的数据复制到同一个表中的一些新创建的列中。有些列为text，有些列为varchar（旧）到not null（新）。我遇到的困难是旧列中有一些空数据，而新列是BEGIN TRY BEGIN TRANSACTION update tblProject set NewBitColumn1 = OldBitColumn1, NewBitColumn2 = OldBitColumn2, NewBitColumn3 = OldBitColumn3, NewVarCharColumn1 = OldTextColumn1, NewVarCharColumn2 = OldTextColumn2, NewVarCharColumn3 = OldTextColumn3, COMMIT TRAN -- Transaction Success END TRY BEGIN CATCH DECLARE @ErrorMessage NVARCHAR(4000) = ERROR_MESSAGE() DECLARE @ErrorSeverity INT = ERROR_SEVERITY() DECLARE @ErrorState INT = ERROR_STATE() IF @@TRANCOUNT > 0 ROLLBACK TRAN --RollBack in case of Error RAISERROR(@ErrorMessage, @ErrorSeverity, @ErrorState) END CATCH 。我怎样才能使旧数据为空，然后新数据得到一个非空值，0或者＆＃39;＆＃39;依赖。

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Answer 1

使用coalesce()：

update tblProject
    set
        NewBitColumn1 = coalesce(OldBitColumn1, 0),
        NewBitColumn2 = coalesce(OldBitColumn2, 0),
        NewBitColumn3 = coalesce(OldBitColumn3, 0),

        NewVarCharColumn1 = coalesce(OldTextColumn1, ''),
        NewVarCharColumn2 = coalesce(OldTextColumn2, ''),
        NewVarCharColumn3 = coalesce(OldTextColumn3, '');