如何根据参数值设置条件 where 子句

Question

我有以下 SQL，

DECLARE @EmployeeID Int

SELECT *
  FROM [Northwind].[dbo].[Orders]
  WHERE OrderID = 10248
  AND EmployeeID = @EmployeeID

我想确定 IF @EmployeeID IS NULL然后不包括AND

就像是，

SELECT *
  FROM [Northwind].[dbo].[Orders]
  WHERE OrderID = 10248
  IF @EmployeeID IS NOT  NULL
  AND EmployeeID = @EmployeeID

我可以考虑创建一个表变量，然后根据参数值对其进行过滤，但是有没有更好的方法？

Answer 1

我想你想要：

WHERE OrderID = 10248 AND
      (@EmployeeId IS NULL OR EmployeeID = @EmployeeID)