Question

I am just looking at the using statement, I have always known what it does but until now not tried using it, I have come up with the below code:

 using (SqlCommand cmd =       new SqlCommand(reportDataSource,           new SqlConnection(Settings.Default.qlsdat_extensionsConnectionString)))  {      cmd.CommandType = CommandType.StoredProcedure;      cmd.Parameters.Add('@Year', SqlDbType.Char, 4).Value = year;      cmd.Parameters.Add('@startDate', SqlDbType.DateTime).Value = start;      cmd.Parameters.Add('@endDate', SqlDbType.DateTime).Value = end;      cmd.Connection.Open();       DataSet dset = new DataSet();      new SqlDataAdapter(cmd).Fill(dset);      this.gridDataSource.DataSource = dset.Tables[0];  } 

This seems to work but is there any point in this since as far as I can tell I would still need to enclose this in a try catch block to catch unforseen errors e.g. sql server down. Am I missing something?

As far as I can currently see it just stops me closing and disposing of cmd but there will be more lines of code due to the try catch still being needed.

Answer 1

This code should be as follows to ensure timely closing of the connection. Closing just the command doesn’t close the connection:

using (SqlConnection con = new SqlConnection(Settings.Default.qlsdat_extensionsConnectionString)) using (SqlCommand cmd = new SqlCommand(reportDataSource, con))          {              cmd.CommandType = CommandType.StoredProcedure;              cmd.Parameters.Add('@Year', SqlDbType.Char, 4).Value = year;              cmd.Parameters.Add('@startDate', SqlDbType.DateTime).Value = start;              cmd.Parameters.Add('@endDate', SqlDbType.DateTime).Value = end;              cmd.Connection.Open();               DataSet dset = new DataSet();              new SqlDataAdapter(cmd).Fill(dset);              this.gridDataSource.DataSource = dset.Tables[0];          } 

To answer your question, you can do the same in a finally block, but this scopes the code nicely and ensures that you remember to clean up.