Question

I have 2 datasets
ds1 and ds2
ds1 contains valid values used in ds2
for e.g.
ds1 contains subject table containing Maths, Science, History.
ds2 contains Student table
Student table contains Subject column.
ds2->Student->Subject values should be present in ds->subject table.

How to implement this type of validation in effective way.
I don’t want to iterate through each row and column of student table.

e.g.
Students Table
Name Subject
Peter Maths
George Science
Joe IT
Roger History

Subjects Table
Subject
Maths
Science
Maths
History

Now I want to validate the data in Students Table against Subject table
Check if the Subject is present in Subjects table or not.
Here I want row Joe IT since IT is not present in Subjects table it is invalid.

Similarly , I need to check Students table data with multiple tables like Subjects.

I want LINQ query.

Answer 1

Use following query

var noSubject =
  ds.Student.AsEnumerable().Where(s => ds.Subject.Rows.Find(s.Subject) == null);