Hi Salam6331,
I guess your question points this piece of code:
public static System.Linq.Expressions.Expression<Func<Table4,bool>> IsEqual(YesNo i)
{
return ((a) => a.Num == (int?)i);
}
What really happens here is you define an expression tree that describes a lambda expression.
Later you can compile this into a delegate or method as you want by calling methods on the result obtained after calling IsEqual(YesNo.No) for e.g. .