这是什么意思“按NULL排序"? [英] what does this mean "order by NULL"

问题描述

我使用oracle 11g.下面的行顺序是空的

i use oracle 11g.what does the line order by null means in the following

select f_value,row_number() over (order by null) as id 
from tableName"

推荐答案

ROW_NUMBER()的OVER()子句需要ORDER BY

使用ORDER BY NULL是一种解决方法，它满足了语法要求，但实际上并未更改数据的顺序.实际上，这是完全不订购的指令.

using ORDER BY NULL is a workaround that satifies the syntax requirement but does not actually change the order of the data. In effect it is an instruction to not order at all.

NB :有些人(包括我自己)更喜欢使用SELECT 1而不是SELECT NULL，但是效果没有差别.

N.B.: some (myself included) prefer to use SELECT 1 instead of SELECT NULL but there is no difference in effect.

底线:不太好，但是可以.

Bottom line: not great, but it works.

提示:TSQL不允许直接使用SELECT 1，但是您可以使用(SELECT 1)

tip: TSQL does not permit the direct use of SELECT 1, but you may use (SELECT 1)

这篇关于这是什么意思“按NULL排序"?的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！