Question

How would I know if a particular data is present in database or not? For E.g. If the Database already has “Student_Id” and “Course_Id” in a table then update the record else insert the record.

I already have a controller action which I use to insert the data, but I want to add an additional feature where it checks the database (SQL Server) and does insert/update based on whether the record is present or now.

I use Linq to SQL to insert data.

Thanks in advance

Answer 1

You could check if the data is there via a simple select statement, prior to adding the data.

bool exists = yourTable.Any(row => row.StudentID == studentId && row.CourseID = courseID);

Ideally though, you should design the database to make Student_Id and Course_Id a combined unique key for this table, so your code won’t be able to add them at all if a record is already there.

As Maess asked, how are the values being generated? Your options could change depending on whether the data is user-generated or not. For example; if you have two dropdown boxes to select a student and a course, don’t allow the user to select a course that the student is already diong.