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C# List.Find and Predicates - How To

I have a list of users that includes name, startdate, and enddate. A user may be listed several times but with diferent start and end dates. I want to create a new list that contains a single entry for each user with that users minimum startdate and maximum enddate. I am using C# and attempting to complete this task using List.Find and Predicates but not having much success. ANy help greatly aprreciated.

TIA

Yurich

I would create a new data source use a SQL query similar to the following (it can be in a stored procedure, doesn't matter):

SELECT User,
(
SELECT Top 1 start_date -- earliest start_date
FROM YourDates
WHERE User = u1.User
ORDER BY start_date
) as start_date,
(
SELECT Top 1 end_date -- latest end_date
FROM YourDates
WHERE User = u1.User
ORDER BY end_date DESC
) as end_date

FROM Users as u1

It can vary a bit depending how you exactly store your data (e.g. User can have UserID PK, not just User, etc.) but that would be the fastest I think.

Good luck,
Yurich

Bob Learned

What have you tried with List.Find and predicates?

Bob

DylanJones1

ASKER

This did what I needed.

List<User> ThisUserList = UserNames.FindAll(delegate(User u) {return ThisUser.UserName == u.UserName; });

ASKER CERTIFIED SOLUTION

Computer101

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