# LINQ Queries

## Content

LINQ queries demonstrate how to operate and query the JSON objects wrapped in an Entity Framework data model. Listed below are some examples of LINQ queries supported by the Entity framework.


**Contains** 
Retrieve records from the **Books** table where the AuthorFirstName contains the letter"A".

```csharp
var histories = from p in db.Books                
        where p.AuthorFirstName.Contains("A") //using Contains to display Author names with "a" in their first name 
                select p;
```


**Count** Count all entities that match a given criterion.
```csharp 
var _count = (from p in db.Books
            select p).Count();//Count Query based on the number of records selected
```
 

**Select and Filter** 
Select records from the **Books** table that belong to a Genre equal to "**autobiography**".
```csharp 
var histories = from p in db.Books
                where p.Genre== "autobiography"
                select p;
```


**Limit** 
Select the first 2 records.
```csharp 
var histories = (from p in db.Books
                select p).Take(2); //taking 2 histories
```


**Order By** 
Sort records by **Title** in descending order. 
```csharp 
var histories = (from p in db.Books
                orderby p.Title descending //Implementing Order By
                select p).Take(2); //taking 2 histories
```


**Group By** Group records from the **Books** table based on the **Title** property. The groups are then ordered in descending order based on the **Title**.
 ```csharp 
var booksTable = context.Books.AsEnumerable();
var queryBooks = from b in booksTable
                 group b by b.Title into newGroup
                 orderby newGroup.Key descending
                 select newGroup;
```