Other

How add join in LINQ?

by Rhyley Bryan

How add join in LINQ?

The following is the Linq query for above SQL query.

  1. var result = (from p in Products join o in Orders on p.ProductId equals o.ProductId into temp from t in temp.DefaultIfEmpty() select new.
  2. {
  3. p.ProductId,
  4. OrderId = (int ? ) t.OrderId,
  5. t.OrderNumber,
  6. p.ProductName,
  7. Quantity = (int ? ) t.Quantity,
  8. t.TotalAmount,

Is LINQ join inner or outer?

Usually linq is using an left outer join for its queries but on some cases it decides to use inner join instead.

How use inner join in LINQ?

In relational database terms, an inner join produces a result set in which each element of the first collection appears one time for every matching element in the second collection. If an element in the first collection has no matching elements, it does not appear in the result set.

How do you write LINQ?

The LINQ query syntax starts with from keyword and ends with select keyword. The following is a sample LINQ query that returns a collection of strings which contains a word “Tutorials”. The following figure shows the structure of LINQ query syntax. Query syntax starts with a From clause followed by a Range variable.

How Write Right join in LINQ?

Right outer join in LINQ

  1. using (JoinEntities Context = new JoinEntities())
  2. {
  3. var rightOuterJoin = from d in Context.DepartmentMasters.
  4. join e in Context.EmployeeMasters on d.DepartmentId equals e.DepartmentId into emp.
  5. from employee in emp.DefaultIfEmpty()
  6. select new.
  7. {
  8. EmployeeCode = employee.Code,

How Use left and right join in LINQ?

A Left Outer join returns all records from the left table and the matching record from the right table. If there are no matching records in the right table then it returns null. If we want to do a Left Outer join in LINQ then we must use the keyword “into” and method “DefaultIfEmpty”.

What is the use of DefaultIfEmpty in LINQ?

The DefaultIfEmpty operator is used to replace an empty collection or sequence with a default valued singleton collection or sequence. Or in other words, it returns a collection or sequence with default values if the source is empty, otherwise return the source.

What does LINQ join do?

This join returns records or rows that are a multiplication of record number from both the tables means each row on the left table will be related to each row of a right table. In LINQ to achieve CROSS JOIN behavior, there is no need to use Join clause and where clause.

What is LINQ example?

Language-Integrated Query (LINQ) is the name for a set of technologies based on the integration of query capabilities directly into the C# language. Traditionally, queries against data are expressed as simple strings without type checking at compile time or IntelliSense support.

Is LINQ better than SQL?

More importantly: when it comes to querying databases, LINQ is in most cases a significantly more productive querying language than SQL. Compared to SQL, LINQ is simpler, tidier, and higher-level. Here’s same query in LINQ.

When to use explicit join clauses in LINQ?

Joins on object collections vs. relational tables. In a LINQ query expression, join operations are performed on object collections. Object collections cannot be “joined” in exactly the same way as two relational tables. In LINQ, explicit join clauses are only required when two source sequences are not tied by any relationship.

How to use join with multiple conditions in LINQ?

I’m trying to implement a query in LINQ that uses a left outer join with multiple conditions in the ON clause. I’ll use the example of the following two tables Project (ProjectID, ProjectName) and Task (TaskID, ProjectID, TaskName, Completed).

When to use the where clause in LINQ?

They should take an object of the type of the table in question and return the key to use in the join. I think you mean this: You can apply the where clause afterwards, not as part of the key selector. Posting because when I started LINQ + EntityFramework, I stared at these examples for a day.

When do you use the into keyword in LINQ?

When used with the join keyword, into will add a variable containing all of the matching items from the join. (This is called a Group Join) so when you use multiple joins do you use the ‘into’ clause and join the next query with that ‘variable’ that you’ve just added? – Jacques Feb 14 ’17 at 16:55