ADO.NET Entity: Insert Update and Delete with Relationship
Few days back I had written an article on Insert/Update/Delete for simple standalone tables at ADO.NET Entity: Insert Update and Delete. Now after that many of you had requested me to put article on how it works with relationship.
Here I will use a database created by me. There will be two tables connected with each other.
Now I will create TestDB.edmx out of this database.
Insert
using (TestDBEntities ctx = new TestDBEntities())
{
//Create new Department
Dept d = new Dept() { DeptName = "ADO Entity" };
//Create new Employee 1
EmpDept ed1 = new EmpDept() { EmpName = "ADO Employee 1" };
//Create new Employee 2
EmpDept ed2 = new EmpDept() { EmpName = "ADO Employee 2" };
//Add employee to the Dept *OBJECT*
d.EmpDept.Add(ed1);
d.EmpDept.Add(ed2);
//Updating the context
ctx.AddToDept(d);
//Save to Database
ctx.SaveChanges();
}
Update
using (TestDBEntities ctx = new TestDBEntities())
{
//Get an existing Department
Dept dep = (from d in ctx.Dept
where d.DeptId == 22
select d).First();
//Set new Department name
dep.DeptName = "ADO.NET 3.0";
//Create new Employee 2
EmpDept ed2 = new EmpDept() { EmpName = "ADO 2" };
//Add *new* employee to the Dept *OBJECT*
dep.EmpDept.Add(ed2);
//Save to Database
ctx.SaveChanges();
}
Delete
using (TestDBEntities ctx = new TestDBEntities())
{
//Get an existing Department
Dept dep = (from d in ctx.Dept.Include("EmpDept")
where d.DeptId == 22
select d).First();
/*
Needd to do ToList() becuase once you delete
a record then iteration will not be possible.
*/
foreach (EmpDept ed in dep.EmpDept.ToList())
{
//This removes relationship from Context
dep.EmpDept.Remove(ed);
//Delete it from context
ctx.DeleteObject(ed);
}
//Delete the master table
ctx.DeleteObject(dep);
//Save to Database
ctx.SaveChanges();
}
Note: during delete you first need to remove the relationship from entity and then delete the object from entity. So you need to keep the child data offline and then do operation. Then delete the main object.
In my next post I will write about “how to select with Relationship”.
Namoskar!!!