UPDATE [Table1]
SET [StatuID] = CASE WHEN [StatuID] - 1 < 0 THEN 0 ELSE [StatuID] - 1 END
WHERE [IndexId] = @IndexId;
UPDATE [Table1]
SET [StatuID] = CASE WHEN [StatuID] - 1 < 0 THEN 0 ELSE [StatuID] - 1 END
WHERE [IndexId] = @IndexId;