I'm coding a transaction manually in ADO.NET. The example I'm working from reuses the SqlCommand
which seem like a fine idea.
However, I have added parameters to my command.
My question is: in the following code, is command.Parameters.Clear()
correct? Or am I doing it wrong?
using (var connection = new SqlConnection(EomAppCommon.EomAppSettings.ConnStr))
{
connection.Open();
SqlTransaction transaction = connection.BeginTransaction();
SqlCommand command = connection.CreateCommand();
command.Transaction = transaction;
try
{
foreach (var itemIDs in this.SelectedItemIds)
{
command.CommandText = "UPDATE Item SET payment_method_id = @batchID WHERE id in (@itemIDs)";
// IS THE FOLLOWING CORRECT?
command.Parameters.Clear();
command.Parameters.Add(new SqlParameter("@batchID", batchID));
command.Parameters.Add(new SqlParameter("@itemIDs", itemIDs));
command.ExecuteNonQuery();
}
transaction.Commit();
}
catch (Exception ex)
{
MessageBox.Show("Failed to update payment batches, rolling back." + ex.Message);
try
{
transaction.Rollback();
}
catch (Exception exRollback)
{
if (!(exRollback is InvalidOperationException)) // connection closed or transaction already rolled back on the server.
{
MessageBox.Show("Failed to roll back. " + exRollback.Message);
}
}
}
}
Since you're repeatedly executing the same query, it's unnecessary to clear them - you can add the parameters outside the loop and just fill them inside.
try
{
command.CommandText = "UPDATE Item SET payment_method_id = @batchID WHERE id in (@itemIDs)";
command.Parameters.Add(new SqlParameter("@batchID", 0));
command.Parameters.Add(new SqlParameter("@itemIDs", ""));
foreach (var itemIDs in this.SelectedItemIds)
{
command.Parameters["@batchID"].Value = batchID;
command.Parameters["@itemIDs"].Value = itemIDs;
command.ExecuteNonQuery();
}
transaction.Commit();
}
Note - you can't use parameters with IN as you've got here - it won't work.
In this condition you need it as you need set new parameters values, so its correct.
By the way, move
command.CommandText = ".."
outside of the loop too, as it's never changed.
来源:https://stackoverflow.com/questions/14374541/should-i-call-parameters-clear-when-reusing-a-sqlcommand-with-a-transation