Sometimes database developer have to change some of the properties of table, due to insertion mistakes. As we have inserted records into Database using entity framework 5, it's time to modify that record and delete that if required through c# programming language.
We (database developer) all know that update and delete query required a condition
through which they retrieve an instance on which action is to be performed.
Update: The update
operation is quite simple in entity framework 5. First retrieve an instance of specified Entity object,
then edit the properties of that instance and finally save the changes to that
context and done. It have a little bit complex syntax in sql programming.
Let’s suppose we have an entry of student named “Student 1”
and we want to change his/her name and age then:
DataContext dc = new DataContext();
Student student = dc.Student.First(s = > s.Name.Equals("Student 1"));
student.Name = "Student 2";
student.Age = 25;
dc.SaveChanges();
Note: "When we are retrieving an instance of Student class and if that student has not been found then there may be an Exception. So better be use 'try catch' block".
DataContext dc = new DataContext();
Student student = dc.Student.First(s = > s.Name.Equals("Student 1"));
student.Name = "Student 2";
student.Age = 25;
dc.SaveChanges();
Execute the code and check the database, you have
successfully made changes through the above c# programming code.
Delete: The delete
operation is little bit different from Update operation. First retrieve an instance of specified Entity object, then
delete that instance from context and finally save changes to context and done.
Let’s suppose we have an entry of student named “Student 2”
and we want to delete then:
DataContext dc = new DataContext();
Student student = dc.Student.First(s = > s.Name.Equals("Student 1"));
dc.Student.Remove(student);
dc.SaveChanges();
DataContext dc = new DataContext();
Student student = dc.Student.First(s = > s.Name.Equals("Student 1"));
dc.Student.Remove(student);
dc.SaveChanges();
Execute the above code of c# programming and check the database, there is no student
named "Student 2".
Note: "When we are retrieving an instance of Student class and if that student has not been found then there may be an Exception. So better be use 'try catch' block".