查询执行

发布于 2024-11-05 03:00:18 字数 407 浏览 0 评论 0原文

1）

declare @OrderBy varchar(100) = 'CompanyName'
declare @SortingOrder varchar(5) = 'desc'

Select * from [User] order by (@OrderBy + '  ' + @SortingOrder)

2）

Select * from [User] order by CompanyName desc

如果我使用第二个查询，那么结果为真（如我预期），但如果我使用第一个查询，那么结果不符合预期。

我的意思是，结果集是通过按公司名称降序排列来显示的。

第一个查询有什么问题？有人请解释一下这一点。

谢谢。

原文

declare @OrderBy varchar(100) = 'CompanyName'
declare @SortingOrder varchar(5) = 'desc'

Select * from [User] order by (@OrderBy + '  ' + @SortingOrder)

Select * from [User] order by CompanyName desc

If I use the 2nd query then the result comes true (as I expected), but if I use the 1st query then result is not as expected.

I mean that the result set is displayed by ordering the company name in descending order.

What is the wrong in 1st query?
Someone please explain this.

thanks.

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第几種人 2024-11-12 03:00:18

对于查询 1，您无法按照您尝试执行的方式动态指定要排序的列。但是，您可以构建一个 sql 字符串并使用 EXEC 执行它：

declare @OrderBy varchar(100) = 'CompanyName'
declare @SortingOrder varchar(5) = 'desc'
declare @sql varchar(1000)
SET @sql = 'Select * from [User] order by ' + @OrderBy + ' ' + @SortingOrder
EXEC(@sql)

或者如果您想避免动态 SQL，您可以在 ORDER BY 中使用 CASE WHEN 语句：

declare @OrderBy varchar(100) = 'CompanyName'
declare @so varchar(5) = 'desc'

SELECT * FROM [User] 
ORDER BY
  CASE WHEN @OrderBy = 'CompanyName' AND @so = 'desc' THEN CompanyName END DESC,
  CASE WHEN @OrderBy = 'CompanyName' AND @so <> 'desc' THEN CompanyName END

For query number 1, you can't specify the column you want to order by dynamically the way you're trying to do it. You could however build a sql string and execute it using EXEC:

declare @OrderBy varchar(100) = 'CompanyName'
declare @SortingOrder varchar(5) = 'desc'
declare @sql varchar(1000)
SET @sql = 'Select * from [User] order by ' + @OrderBy + ' ' + @SortingOrder
EXEC(@sql)

Or if you want to avoid dynamic SQL, you can use a CASE WHEN statement in your ORDER BY:

declare @OrderBy varchar(100) = 'CompanyName'
declare @so varchar(5) = 'desc'

SELECT * FROM [User] 
ORDER BY
  CASE WHEN @OrderBy = 'CompanyName' AND @so = 'desc' THEN CompanyName END DESC,
  CASE WHEN @OrderBy = 'CompanyName' AND @so <> 'desc' THEN CompanyName END

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