从表中选择前N行 [英] select the TOP N rows from a table
本文介绍了从表中选择前N行的处理方法,对大家解决问题具有一定的参考价值,需要的朋友们下面随着小编来一起学习吧!
问题描述
我正在进行一些分页,并且需要进行一些查询并获得定义为slicing的结果形式. 例如:我需要获取所有20n< x < 40n等.
I am making some paging, and I need to make some query and get the result form defined slicing . for example: I need to get all "top" rows in range 20n < x < 40n etc.
SELECT * FROM Reflow
WHERE ReflowProcessID = somenumber
ORDER BY ID DESC;
现在我需要按名为ID的列进行滑动.
and now I need to make my sliding by column called ID .
有什么建议怎么做?我需要在mysql,mssql和oracle上运行查询.
Any suggestions how to so ? I need to run my query on mysql, mssql, and oracle.
推荐答案
假设您的页面大小为20条记录,并且您想获取第2页,则应按以下步骤操作:
Assuming your page size is 20 record, and you wanna get page number 2, here is how you would do it:
SQL Server,Oracle:
SQL Server, Oracle:
SELECT * -- <-- pick any columns here from your table, if you wanna exclude the RowNumber
FROM (SELECT ROW_NUMBER OVER(ORDER BY ID DESC) RowNumber, *
FROM Reflow
WHERE ReflowProcessID = somenumber) t
WHERE RowNumber >= 20 AND RowNumber <= 40
MySQL:
SELECT *
FROM Reflow
WHERE ReflowProcessID = somenumber
ORDER BY ID DESC
LIMIT 20 OFFSET 20
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