LINQ - Referential integrity - Asked By waseem kaleem on 04-Oct-11 04:41 AM

Suppose two tables
Category(id,name,description) parent table
book(id,name,catoryId) child table
I want to perform some checks in linq to sql
1)Only those record is stored in Child Table whose category id exists in Parent Table.
2)all those records of parent table which contain records in child are not deleted 

Hi,

For those 2 requirement i would say just use Join which give u a common data which is avaliable in both the table that u can do it like below query

var test = from a in tableA
        Join b in tableB on a.Id = b.Id
        select {new A.Id,A.name,B.Id,B.test}
        order by A.Id

var query = from c in db.Category
            join o in db.book
               on c.id equals o.id into sr
            from x in sr.DefaultIfEmpty()
            select new {
               CategoryID = c.id, Name=c.name,
               BookID = x.id == null ? -1 : x.id};   

 
 try this query 

var Data = from a in book
Join b in Category on a.catoryId = b.id
select {new a.Id,a.name,a.catoryId}