SELECT [Projname],[version],[state] FROM [dbo].[Goods] WHERE
[Projname] = CASE WHEN @Projname IS NULL THEN [Projname] ELSE @Projname END
或者
SELECT [Projname],[version],[state] FROM [dbo].[Goods] WHERE
([Projname] = @Projname OR @Projname IS NULL )
SELECT [Projname],[version],[state] FROM [dbo].[Goods] WHERE
[Projname] = CASE WHEN @Projname IS NULL THEN [Projname] ELSE @Projname END
或者
SELECT [Projname],[version],[state] FROM [dbo].[Goods] WHERE
([Projname] = @Projname OR @Projname IS NULL )