c# - Dapper + MSAccess: How to get identifier of inserted row

Question

I am using Dapper with C# and back end is MS Access. My DAL method inserts record in database. I want to return unique identifier (or updated POCO with unique identifier) of the inserted row. I am expecting my function something like follows (I know this does not work; just to explain what I want): -

public MyPoco Insert(MyPoco myPoco)
{
    sql = @"INSERT INTO MyTable (Field1, Field2) VALUES (@Field1, @Field2)";
    var param = GetMappedParams(myPoco);//ID property here is null.
    var result = _connection.Query<MyPoco>(sql, param, null, false, null, CommandType.Text);.Single();
    return result;//This result now contains ID that is created by database.
}

I am from NHibernate world and POCO updates automatically with NH. If not; we can call Refresh method and it updates the ID. I am not aware how to achieve this with Dapper.

I read this question on SO which is not relevant as it talks about SQL Server.

Another this question does not have accepted answer.

I read this question where accepted answer explains pit-falls of using @@Identity.

Answer 1

This is what works for me:

static MyPoco Insert(MyPoco myPoco)
{
    string sql = "INSERT INTO MyTable (Field1, Field2) VALUES (@Field1, @Field2)";
    _connection.Execute(sql, new {myPoco.Field1, myPoco.Field2});
    myPoco.ID = _connection.Query<int>("SELECT @@IDENTITY").Single();
    return myPoco;  // This result now contains ID that is created by database.
}

Note that this will work with an OleDbConnection to the Access database, but it will not work with an OdbcConnection.

Edit re: comment

To ensure that the Connection remains open between the INSERT and the SELECT calls, we could do this:

static void Insert(MyPoco myPoco)
{
    string sql = "INSERT INTO MyTable (Field1, Field2) VALUES (@Field1, @Field2)";
    bool connAlreadyOpen = (_connection.State == System.Data.ConnectionState.Open);
    if (!connAlreadyOpen)
    {
        _connection.Open();
    }
    _connection.Execute(sql, new {myPoco.Field1, myPoco.Field2});
    myPoco.ID = _connection.Query<int>("SELECT @@IDENTITY").Single();
    if (!connAlreadyOpen)
    {
        _connection.Close();
    }
    return;  // (myPoco now contains ID that is created by database.)
}