Question

Entity Frame 5.0 question.

I am new to Entity Frame, basically I have a table “MyPIN”.

[Table("MyPIN")]
public class BatchPINDetail
{
    public BatchPINDetail();
    public int Number { get; set; }

I want to run a query

int x = the biggest Number FROM MyPIN 

The correspond codes are:

public class InContext : DbContext
{
    public InContext();
    public InContext(string connectionString);

    public DbSet<BatchDetail> BatchDetailsRecords { get; set; }

}

Question 1: I am not sure how to retrieve it.

Question 2: After I get the value, I want to reassign the value, say Number += 1; I need to write it to DB.

Thanks for help.

Answer 1

InContext inContext = new InContext(cnStr);
// get first biggest item
BatchPINDetail entity = inContext.BatchDetailsRecords
                                 .OrderByDescending(x => x.Number)
                                 .First();
// get all biggest items
BatchPINDetail entities = inContext.BatchDetailsRecords
                                 .Where(x => x.Number == x.Max(x => x.Number))
                                 .ToArray();

// and if you just want to get biggest number. 
// but note that if you just change `num` nothing will happen.
int num = inContext.BatchDetailsRecords.Max(x => x.Number);

entity.Number += 1;
inContext.SaveChanges();