# Simple Queries

## Simple queries

#### We shall use this data source to see some queries

```csharp
public class Student
{
    public int StudentID { get; set; }
    public string StudentName { get; set; }
    public int Mark { get; set; }
    public string City { get; set; }
}

Student[] studentList =
{
    new Student() { StudentID = 1, StudentName = "John Nigel", Mark = 73, City ="NYC"} ,
    new Student() { StudentID = 2, StudentName = "Alex Roma",  Mark = 51 , City ="CA"} ,
    new Student() { StudentID = 3, StudentName = "Noha Shamil",  Mark = 88 , City ="CA"} ,
    new Student() { StudentID = 4, StudentName = "James Palatte" , Mark = 60, City ="NYC"} ,
    new Student() { StudentID = 5, StudentName = "Ron Jenova" , Mark = 85 , City ="NYC"}
};
```

#### Display `Name` and `Mark` of students with `Mark` higher than 80:

```csharp
var toppers = from student in studentList
                where student.Mark > 80
                select student;

foreach (var s in toppers)
Console.WriteLine(s.StudentName + " " + s.Mark);

Console.ReadKey();
```

> Try the same in method syntax

#### Display `Name` and `City`of students from NYC with `Mark` higher than 70:

```csharp
var res = studentList.Where(s=>s.Mark >70 && s.City =="NYC");

foreach (var s in res)
    Console.WriteLine(s.StudentName + " " + s.City);

Console.ReadKey();
```

#### How many have score 70 and above?

```csharp
var res = studentList.Where(s=>s.Mark >70 && s.City =="NYC").Count();

Console.WriteLine(res);

Console.ReadKey();
```

#### What is the name of student with ID number 4?

```csharp
var res = studentList.Single(s => s.StudentID == 4);

Console.WriteLine(res.StudentName);

Console.ReadKey();
```

#### Display the name of the first student who has scored less than 60

```csharp
var res1 = studentList.First(s=>s.Mark<60);
Console.WriteLine(res1.StudentName);

//or

var res2 = studentList.Where(s => s.Mark < 60).First();
Console.WriteLine(res2.StudentName);

Console.ReadKey();
```

> Try to find who is the last student from the city "CA”?


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