i want select distinct firstName's column from Database with linq
my class is:
public partial class user
{
public string firstName{ get; set; }
public string lastName{ get; set; }
public int dgree{ get; set; }
public string class{ get; set; }
}
i using below code but return full list.
var query = (from user _db.Users
select user).Distinct().OrderBy(u=>u.firstName).ToList();
To return distinct values from a list of custom objects you need to impelement the IEquatable<T> interface in the user class.
public partial class user : IEquatable<user>
{
public string firstName{ get; set; }
public string lastName{ get; set; }
public int dgree{ get; set; }
public string class{ get; set; }
public bool Equals(Product other)
{
//check if the objects are the same based on your properties:
//example
if (firstName == other.firstName)
return true; //then i assume they're equal and return true. You can check here all your properites that make an object unique.
return false;
}
public override int GetHashCode()
{
// If Equals() returns true for a pair of objects
// then GetHashCode() must return the same value for these objects.
}
}`
More examples at : http://msdn.microsoft.com/en-us/library/bb348436.aspx
The way you wrote it you get only exact duplicate lines cut. do you get any of them in your result ?
if you need to distinct on specific column check out this answer: Distinct By specific property
