How to specify Table schema using entity framework databse first approach

You should create a configuration class based on your model.In this you can specify the behavior of that property

public class SalesOrderConfiguration:EntityTypeConfiguration<salesorder>
    {
       public SalesOrderConfiguration()
       {
           Property(co => co.CustomerName).HasMaxLength(30).IsRequired();
           Property(co => co.PONumber).HasMaxLength(10).IsOptional();
       }
    }

Your model class will look like below

public class SalesOrder
   {

       public int SalesOrderId { get; set; }
       public string CustomerName { get; set; }
       public string PONumber { get; set; }
   }

You can specify the configuration class in your DbContext

public class SalesContext:DbContext
   {
       public SalesContext()
           : base("DefaultConnection")
       {

       }

       public DbSet<salesorder> SalesOrders { get; set; }

       protected override void OnModelCreating(DbModelBuilder modelBuilder)
       {
           modelBuilder.Configurations.Add(new SalesOrderConfiguration());
       }
   }</salesorder>

Hope this helps