从MsSQL转移到MySQL错误

Question

Im trying to transfer data between databases (from MsSQL Server to MySQL). Source database has ~2700 records. And when im executing program, every 400-600 record VS throws an exception:

Invalid attempt to call IsDBNull when reader is closed.

Code:

foreach (var product in products)
        {
            var prd = product;

            var cmd = connection.CreateCommand();

            cmd.CommandText =
                "INSERT INTO Product(CategoryID, Position, PresentItemID, Guid, ThumbX, ThumbY, " +
                "ImgX, ImgY, Name, Description, IsAvailable, TotalStock, Price, ListPrice, Size, " +
                "meta_tag, desc_tag, page_metatags, FreeDescription, IsVintage, OnSale, Valentine)" +
                "VALUES(@CategoryID, @Position, @PresentItemID, @Guid, @ThumbX, @ThumbY, " +
                "@ImgX, @ImgY, @Name, @Description, @IsAvailable, @TotalStock, @Price, @ListPrice, @Size, " +
                "@meta_tag, @desc_tag, @page_metatags, @FreeDescription, @IsVintage, @OnSale, @Valentine)";

            cmd.Parameters.AddWithValue("@CategoryID", prd.CategoryID);
            cmd.Parameters.AddWithValue("@Position", prd.Position);
            cmd.Parameters.AddWithValue("@PresentItemID", prd.PresentItemID);
            cmd.Parameters.AddWithValue("@Guid", prd.Guid);
            ...
            cmd.Parameters.AddWithValue("@IsVintage", prd.IsVintage);
            cmd.Parameters.AddWithValue("@OnSale", prd.OnSale);
            cmd.Parameters.AddWithValue("@Valentine", prd.Valentine);
            cmd.ExecuteNonQuery();
            progressBar1.PerformStep();
        }

I tried to add this code

    List<Product> prd = products.ToList();

and transfer data from list, not directly from database, but had same error.

Thanks for help.

Answer 1

var cmd = connection.CreateCommand();

You probably need to properly dispose the object being created:

using(var cmd = connection.CreateCommand())
{
    cmd.CommandText = ...
}

Answer 2

To resolve this problem I created back-up of source database, and installed it on machine with destination database. Then programm was executed without any problems. Still cant realize why this exception happened to me.