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POHow to join multiple tables using LINQ-to-SQL?
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  1. POHow to join multiple tables using LINQ-to-SQL?
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    copied!<p>I'm quite new to linq, so please bear with me. </p> <p>I'm working on a asp.net webpage and I want to add a "search function" (textbox where user inputs name or surname or both or just parts of it and gets back all related information). I have two tables ("Person" and "Application") and I want to display some columns from Person (name and surname) and some from Application (score, position,...). I know how I could do it using sql, but I want to learn more about linq and thus I want to do it using linq.</p> <p>For now I got two main ideas:</p> <p>1.)</p> <pre><code> var person = dataContext.GetTable&lt;Person&gt;(); var application = dataContext.GetTable&lt;Application&gt;(); var p1 = from p in Person where(p.Name.Contains(tokens[0]) || p.Surname.Contains(tokens[1])) select new {Id = p.Id, Name = p.Name, Surname = p.Surname}; //or maybe without this line //I don't know how to do the following properly var result = from a in Application where a.FK_Application.Equals(index) //just to get the "right" type of application //this is not right, but I don't know how to do it better join p1 on p1.Id == a.FK_Person </code></pre> <p>2.) The other idea is just to go through "Application" and instead of "join p1 ..." to use</p> <pre><code>var result = from a in Application where a.FK_Application.Equals(index) //just to get the "right" type of application join p from Person on p.Id == a.FK_Person where p.Name.Contains(tokens[0]) || p.Surname.Contains(tokens[1]) </code></pre> <p>I think that first idea is better for queries without the first "where" condition, which I also intended to use. Regardless of what is better (faster), I still don't know how to do it using linq. Also in the end I wanted to display / select just some parts (columns) of the result (joined tables + filtering conditions).</p> <p>I really want to know how to do such things using linq as I'll be dealing also with some similar problems with local data, where I can use only linq. Could somebody please explain me how to do it, I spent days trying to figure it out and searching on the Internet for answers.</p>
 

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