Sample LINQ with Multiple Joins and Selected Columns

gmtzgtz

Rate me:

4.58/5 (8 votes)

1 Jun 2020CPOL

27.1K

How to write a LINQ statement with multiple joins

In this post, we will go through a sample that shows how to write a LINQ statement with multiple joins.

If you are like me, I sometimes find it difficult to remember the syntax of LINQ statements because I jump from T-SQL to ASP.NET and C#.

I was searching for a sample that may show how to write a LINQ statement with multiple joins and I had little luck finding it, so finally, after I put my few brain cells in action, I came up with the following:

var dbRegCourses = (from a in db.CourseRegistries
                    join b in db.Courses on a.courseid equals b.id
                    join c in db.aspnet_Users on a.userid equals c.UserId
                    where a.userid == sUserID
                    orderby a.regdate, b.code, b.description,
                            b.instructor, b.date, b.venue
                    select new
                    {
                      a.regdate, b.code, b.description,
                      b.instructor, b.date, b.venue});

if (dbRegCourses.Count() > 0)
{
    ResultLbl.Text = "We found that you are registered to: " +     
                      dbRegCourses.Count().ToString() + " Courses.";
    return;
}

If you notice, here we are joining three tables, using a where statement and then picking and choosing columns from at least two tables.

I also added an if statement bottom to see if I got any rows back from the LINQ Statement and if that's the case, return a message.

Hope this helps somebody out there,
Will

This article was originally posted at http://feedproxy.google.com/~r/blogspot/NyVKAz/~3/rDUu6SDG7LQ/sample-linq-with-multiple-joins-and.html

License

This article, along with any associated source code and files, is licensed under The Code Project Open License (CPOL)

Written By

gmtzgtz

United States

This member has not yet provided a Biography. Assume it's interesting and varied, and probably something to do with programming.

var fundraisingGridItems = (from product in clubDb.FundraisingProducts join plan in clubDb.FundrasingPlans on product.ProductID equals plan.ProductID join template in clubDb.CustomTemplates on product.CustomTemplateID equals template.ID into templateList from tem in templateList.DefaultIfEmpty() where product.IsVisible == 'T' select new FundraisingGridItem { // Stripe Product ProductID = product.ProductID, Name = product.Name, Description = product.Description, StatementDescriptor = product.StatementDescriptor, CustomTemplateID = product.CustomTemplateID, CustomTemplate = tem.Name == null ? "N/A" : tem.Name, DisplayFrom = product.DisplayFrom, DisplayTo = product.DisplayTo, DTS = product.DTS, // Stripe Plan Nickname = plan.Nickname, Amount = plan.Amount, Currency = plan.Currency, Interval = plan.Interval, IntervalCount = plan.IntervalCount, StartDate = plan.StartDate, Iterations = plan.Iterations } ).ToList().OrderByDescending(x=> x.DTS);

Use Ctrl+Left/Right to switch messages, Ctrl+Up/Down to switch threads, Ctrl+Shift+Left/Right to switch pages.

Sample LINQ with Multiple Joins and Selected Columns

License

Comments and Discussions