Zoltan Halasz

Posted on Nov 7, 2019 • Updated on Dec 19, 2019

Bulk Insert in Dapper into MS SQL

#csharp #sql

I am collecting costs by employee from 6 sources and then insert them into a a GeneratedDetail table. But the collected data has 1000+ rows, and the insertion one by one row is very slow. I needed to find a bulk insert solution.

I am using Dapper as ORM in my C# project, and MS SQL Database.
According to research, my approach would be as below. It works now quite fast, I am satisfied with the speed of execution. Feel free to comment and propose a better solution.
note: spGeneratedDetailInsert is a stored procedure with many parameters.

    public  void GeneratedDetailInsertBulk1(List<GeneratedDetail> DetailList)
    {
        using (IDbConnection connection = new System.Data.SqlClient.SqlConnection(connectionString))
        {
            var sql = "";           
            foreach (var mydet in DetailList)
            {               
                sql = sql + "Exec spGeneratedDetailInsert '" + mydet.BillingCode + "', " +
                    mydet.Emp_id + ", '" +
                    mydet.Emp_name + "', " +
                    mydet.HrId + ", " +
                    mydet.Entity_id + ", " +
                    mydet.BU_id + ", '" +
                    mydet.Currency + "', '" +
                    mydet.Item + "', " +
                    mydet.ExchangeRate + ", " +
                    mydet.InitValueRON + ", " +
                    mydet.InitValueCurr + ", " +
                    mydet.MUValueCurr + ", " +
                    mydet.TotalRon + ", '" +
                    mydet.ServiceType + "', '" +
                    mydet.CostCategory + "', '" +
                    mydet.UpdatedBy + "', '" +
                    mydet.UpdatedAt + "', '" +
                    mydet.PeriodId + "' ; ";                                   
            }
             connection.Execute(sql);
        }
    }

Note: I am not using Dapper Plus, and I don't want to.

Top comments (8)

Evaldas Buinauskas • Nov 7 '19 • Edited

Why not simple?

public void GeneratedDetailInsertBulk1 (List DetailList)
{
    using (var connection = new System.Data.SqlClient.SqlConnection (connectionString))
    {
        const string sql = "spGeneratedDetailInsert";

        connection.Execute (sql, DetailList, commandType : CommandType.StoredProcedure);
    }
}

What you have there is a SQL injection vulnerability, don't concatenate strings to build SQL statements.

Also Dapper should support a list of parameters and be able to execute that stored procedure for each list parameter.

If it actually doesn't, foreach will definitely work:

public void GeneratedDetailInsertBulk1 (List DetailList)
{
    using (var connection = new System.Data.SqlClient.SqlConnection (connectionString))
    {
        const string sql = "spGeneratedDetailInsert";

        foreach (var detail in DetailList)
        {
            connection.Execute (sql, detail, commandType : CommandType.StoredProcedure);
        }
    }
}

The better way would be to not use stored procedures and if you need an actual bulk insert, convert your list to a DataTable, using a method, such as in here and then do the actual bulk insert, take sample code from this StackOverflow question

Zoltan Halasz • Nov 7 '19 • Edited

I appreciate your response. Structurally your solution is more beautiful, but mine is 2x faster. I have 850 records, and my solution inserts them in 15 sec, whereas the proposed solution is around 33 sec. Speed is very important here, as there will be around 1500 - 2000 records on a monthly basis, and we will use an Azure SQL database to store the data, so updates are a bit slow.
Thank you for your suggestion anyway, it's great way to learn and try.

Evaldas Buinauskas • Nov 7 '19

850 records in 15 seconds is still really, really slow :)

Are your inserts complicated so that you need a stored procedure?

With a proper bulk insert you could do all of that in less than a second.

Zoltan Halasz • Nov 7 '19

Yes, I checked your suggestion with the proper SQL bulk insert. It now works, indeed around 1 second. I needed to convert the List to Datatable using the suggested method. Thank you! :)

Evaldas Buinauskas • Nov 7 '19

There you go, way better than initial way you had it. Also tons of times faster.

Mike Pendon (Zym) • Dec 26 '19 • Edited

Hi, had you tried RepoDb.InsertAll(DetailList)? That is a "packed" statements. The first run could be slower by 1 sec due to compilation. The second run would be extremely fast.

Otherwise, RepoDb.BulkInsert which is using the SqlBulkCopy underneath that does the real bulk operation. That would only take 1 millisecond, I suppose.

Please let us hear it if you have done so. Thanks

Zoltan Halasz • Dec 27 '19

Thanks Michael, I figured it out already, see my post: dev.to/zoltanhalasz/bulk-insert-wi...

Mike Pendon (Zym) • Dec 27 '19

Great and thanks!

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Bulk Insert in Dapper into MS SQL

Top comments (8)

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