SQL（或Linq）选择以前的值 [英] SQL (or Linq) Select previous value

问题描述

嘿所有，



我想根据DateTime值（特别是年份）从当前记录中的一个记录中选择一个值正在输入和已经在那里（除非第一行）。我的id因为删除而跳过（我认为修复它的方法也适用）。



有人想帮我查询吗？ （注意：我之前已经重新订购了ID，但是我忘记了当我这样做时使用了哪种语言，我似乎无法找到它的参考，这样做通常看起来像是浪费资源） 。



谢谢，



Ruben

Hey all,

I would like to select a value from a record that is one previous from the current record based on the DateTime value (specifically: year) that is being input and one that is already in there (unless first row). My id's skip because of deletes (I suppose a fix-it method for that would work too).

Anyone want to help me with the query? (Note: I have re-ordered ID's before, but I forget which language that was in when I did it, I can't seem to find a reference on that, and doing that often seems like it would be a waste of resources).

Thanks,

Ruben

推荐答案

我希望这可以帮到你

I hope this help you

//list object
var lstValue = new List<int>();
//insert 0 -> 19
for (var i = 0; i < 20; i++)
    lstValue.Add(i);
//set up currentValue
var crValue = 3;
//sort list by
lstValue = lstValue.OrderByDescending(s => s).ToList();
//get index of current value
var index = lstValue.IndexOf(crValue);
Console.WriteLine(index);
//get value previous
if (index > 0)
{
    var prvValue = lstValue.Skip(index - 1).First();
    Console.WriteLine(prvValue);
}

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