CODEWITHSUNDEEP
c#linq
Sachin Prasad
Sachin Prasad

Reputation: 5411

Linq Query to get two different values from a single list

Date           value
10/03/2014      77  
10/02/2015      66

10/01/2016      12    
10/01/2016      34
10/01/2016      55

---
---

Till 30 records

I want to write a linq Query to get Values for last 30 days plus one value before last 30 days.

So I want a response

All these records

10/01/2016      12    
10/01/2016      34
10/01/2016      55

---
---

Plus one record 

10/02/2015      66

Just want to know is it even possible or should I get these values in two different query. Note I am using mongodb.

Upvotes: 0

Views: 329

Answers (2)

ZoolWay
ZoolWay

Reputation: 5505

With the few information:

var last30Days = sourceList.Where(rec => rec.DateField.Date >= DateTime.Today.AddDays(-30));
var firstOneAfter30Days = sourceList.Where(rec => rec.DateField.Date < DateTime.Today.AddDays(-30)).Take(1);
var allTogether = last30Days.Union(firstOneAfter30Days);

Note: Take(1) could be FirstOrDefault() too. You might write it in one line but this makes it more clear.

Upvotes: 1

Oliver
Oliver

Reputation: 9002

You could do something like the following. I have used source to refer to your record set.

//Create your "Last 30 days" timeframe
DateTime endDate = DateTime.Now;    
DateTime startDate = endDate.AddDays(-30);

//Use a query to get the "one before" record
var firstBeforeStart = source.FirstOrDefault(i => i.Date < startDate);

//Use the date of the "one before" record to calculate a query start date
var queryStart = firstBeforeStart == null ? startDate : firstBeforeStart.Date;

//Run another query to get all data based on the amended query start date
var allRecords = source.Where(i => i.Date >= queryStart && i.Date < endDate);

Upvotes: 0

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