What is the appropriate procedure for updating or deleting many EntityFramework entities?

.net c# entity-framework sql

Question

In SQL one might sometimes write something like

DELETE FROM table WHERE column IS NULL

or

UPDATE table SET column1=value WHERE column2 IS NULL

or any other criterion that might apply to multiple rows.

As far as I can tell, the best EntityFramework can do is something like

foreach (var entity in db.Table.Where(row => row.Column == null))
    db.Table.Remove(entity);   // or entity.Column2 = value;
db.SaveChanges();

But of course that will retrieve all the entities, and then run a separate DELETE query for each. Surely that must be much slower if there are many entities that satisfy the criterion.

So, cut a long story short, is there any support in EntityFramework for updating or deleting multiple entities in a single query?

1
25
3/19/2012 7:56:56 PM

Accepted Answer

EF doesn't have support for batch updates or deletes but you can simply do:

db.Database.ExecuteSqlCommand("DELETE FROM ...", someParameter);

Edit:

People who really want to stick with LINQ queries sometimes use workaround where they first create select SQL query from LINQ query:

string query = db.Table.Where(row => row.Column == null).ToString();

and after that find the first occurrence of FROM and replace the beginning of the query with DELETE and execute result with ExecuteSqlCommand. The problem with this approach is that it works only in basic scenarios. It will not work with entity splitting or some inheritance mapping where you need to delete two or more records per entity.

13
3/19/2012 8:10:28 PM

Popular Answer

Take a look to Entity Framework Extensions (Multiple entity updates). This project allow set operations using lambda expressions. Samples from doc:

this.Container.Devices.Delete(o => o.Id == 1);

this.Container.Devices.Update(
     o => new Device() { 
        LastOrderRequest = DateTime.Now, 
        Description = o.Description + "teste"
     }, 
     o => o.Id == 1);

Digging EFE project source code you can see how automatize @Ladislav Mrnka second approach also adding setting operations:

    public override string GetDmlCommand()
    {
        //Recover Table Name

        StringBuilder updateCommand = new StringBuilder();
        updateCommand.Append("UPDATE ");
        updateCommand.Append(MetadataAccessor.GetTableNameByEdmType(
                                  typeof(T).Name));
        updateCommand.Append(" ");
        updateCommand.Append(setParser.ParseExpression());
        updateCommand.Append(whereParser.ParseExpression());

        return updateCommand.ToString();
    }

Edited 3 years latter

Take a look to this great answer: https://stackoverflow.com/a/12751429



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