How to use joins,first or default data retrieval and sorting functionality using LINQ and EF?
While writing LINQ, you may find this code snippet very useful. I have mentioned few examples to clear the syntax.
LINQ stands for Language-Integrated Query. It has powerful query capabilities and easy to understand.
Description-
Multiple tables can be joined and data can be retrieved from it using LINQ query.
private yourentityname db = new yourentityname ();
Make sure entity name should be matched with entity name present in config file. At the time of creation of edmx file it gets saved.
var outputResult = (from firobj in db.firsttablename
join secobj in db.secondtablename
on firobj.firstprimarykey equals secobj.secondprimarykey
where firobj.columnname == somevalue
select new
{
firobj.columnname1_in_firsttable,
firobj.columnname2_in_firsttable,
secobj.columnname1_in_secondtable,
secobj.columnname2_in_secondtable
}).ToList();
How to sort resultset using LINQ?
var outputSorted = outputResult.OrderBy(x => x.columnname).ThenByDescending(y => y.columnname);
In above query, Orderby clause is used to sort data in descending order.
How to retrive data which is first or default one using LINQ and entity framework?
Yourtablename obj = db.yourtablename.FirstOrDefault(t => t.columnname == some_variable_or_some_value);
Above query is used only when single data needs to be fetched from tables of database.