Entity Framework: Insert, Update, Delete records
Every .NET developer sometime will start using ADO.NET Entity Framework.
And first question will be such as how to insert, update and delete records.
Performing basic Inser, Update and Delete operations via the Entity Framework is very straight forward.
Before you make any of thase operations you need to declare entyty
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StudentDBEntities entities = new StudentDBEntities(); |
Inserting
To Insert the record we can write the following code:
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public void UpdateStudent(Student student){ //Add to memory entities.AddToStudents(student); //Save to database entities.SaveChanges(); } |
As you can se it's really simple 2 lines of code sample. If you you have entity objects with small amount of data, like, FirstName and LastName you can use next code to perform inserting:
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public void UpdateStudent(string firstName, string lastName){ var student = new Student() { FirstName = firstName, Lastname = lastName } //Add to memory entities.AddToStudents(student); //Save to database entities.SaveChanges(); } |
This will create new istance of Student object with first and last name and perform inserting. For a good coding please use try{}catch{} and check values for null.
Updating
To Update the record we can write the following code :
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public void UpdateStudent(Student student){ var stud = entities.Students.FirstOrDefault(c => c.ID == student.ID); stud.FirstName = student.Forename; stud.LastName = student.Surname; entities.SaveChanges(); } |
But what if the object we are updating contains a lot of attributes. Surely updating each attribute seperately before calling a Save is a little overkill.
Luckily we are providied with a solution which allows us to attach to a record within the context, perform a straight replace on the record with the new modified record and save back the changes, and all in just 3 lines of code:
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public void UpdateStudent(Student student) { entities.Students.Attach(entities.Students.Single(c => c.ID == student.ID)); entities.Students.ApplyCurrentValues(student); entities.Savechanges(); } |
It makes updating short coded and developer life easier.
Deleting
And finaly, perfoming Insert and Update operations we need to perfome Delete operetion also.
Sample deleting code operetion is below:
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public void UpdateStudent(Student student) { var stud = (from s1 in entities.Students where s1.ID== student.ID select s1).FirstOrDefault(); //Delete it from memory entities.DeleteObject(stud); //Save to database entities.SaveChanges(); } |
FirstOrDefault - gives us null object or first found record.
Also we can perform deleting by passing just a value of Student Id:
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public void UpdateStudent(int studentId) { var stud = (from s1 in entities.Students where s1.ID == studentId select s1).FirstOrDefault(); //Delete it from memory entities.DeleteObject(stud); //Save to database entities.SaveChanges(); } |
As you can see, nothing easier could be.
Happy coding!
February 28th, 2013 - 20:02
Thanks!