Question

我需要允许用户查询所有或部分记录。现在我这样做：

DECLARE @Limit INT = NULL

IF @Limit IS NULL SELECT @Limit = COUNT(ID) FROM vwNotifications

SELECT TOP (@Limit) ROW_NUMBER() OVER(ORDER BY Type, CreatedBy DESC) AS Row, Title
FROM vwNotifications

有没有办法可以在不使用COUNT查询的情况下执行此操作？

Answer 1

你有两个选择

如果它是0，那么

1可以达到20亿但是又一次..你真的想在一次拍摄中返回20亿行吗？

DECLARE @Limit INT = NULL

SELECT @Limit = COALESCE(@Limit, 200000000)

SELECT TOP (@Limit) ROW_NUMBER() OVER(ORDER BY Type, CreatedBy DESC) AS Row, Title
FROM vwNotifications

或做一个if else

DECLARE @Limit INT = NULL

IF @Limit IS NULL

SELECT  ROW_NUMBER() OVER(ORDER BY Type, CreatedBy DESC) AS Row, Title
FROM vwNotifications

else

SELECT TOP (@Limit) ROW_NUMBER() OVER(ORDER BY Type, CreatedBy DESC) AS Row, Title
FROM vwNotifications

Answer 2

假设您的表永远不会包含超过整数支持的行数（即主键是int而不是bigint，实际上可能是这样的：

DECLARE @Limit INT = NULL 

IF @Limit IS NULL OR @Limit = 0
   SET @Limit = 2147483647  -- Max Int

SELECT TOP (@Limit) ROW_NUMBER() OVER(ORDER BY Type, CreatedBy DESC) AS Row, Title 
FROM vwNotifications

您的其他选项是if语句和两个查询..

TSQL：TOP的动态值

2 个答案: