How to catch SQLServer timeout exceptions

Question

I need to specifically catch SQL server timeout exceptions so that they can be handled differently. I know I could catch the SqlException and then check if the message string Contains "Timeout" but was wondering if there is a better way to do it?

try
{
    //some code
}
catch (SqlException ex)
{

    if (ex.Message.Contains("Timeout"))
    {
         //handle timeout
    }
    else
    {
         throw;
    }
}

Answer 1

To check for a timeout, I believe you check the value of ex.Number. If it is -2, then you have a timeout situation.

-2 is the error code for timeout, returned from DBNETLIB, the MDAC driver for SQL Server. This can be seen by downloading Reflector, and looking under System.Data.SqlClient.TdsEnums for TIMEOUT_EXPIRED.

Your code would read:

if (ex.Number == -2)
{
     //handle timeout
}

Code to demonstrate failure:

try
{
    SqlConnection sql = new SqlConnection(@"Network Library=DBMSSOCN;Data Source=YourServer,1433;Initial Catalog=YourDB;Integrated Security=SSPI;");
    sql.Open();

    SqlCommand cmd = sql.CreateCommand();
    cmd.CommandText = "DECLARE @i int WHILE EXISTS (SELECT 1 from sysobjects) BEGIN SELECT @i = 1 END";
    cmd.ExecuteNonQuery(); // This line will timeout.

    cmd.Dispose();
    sql.Close();
}
catch (SqlException ex)
{
    if (ex.Number == -2) {
        Console.WriteLine ("Timeout occurred");
    }
}

Answer 2

here: http://www.tech-archive.net/Archive/DotNet/microsoft.public.dotnet.framework.adonet/2006-10/msg00064.html

You can read also that Thomas Weingartner wrote:

Timeout: SqlException.Number == -2 (This is an ADO.NET error code)
General Network Error: SqlException.Number == 11
Deadlock: SqlException.Number == 1205 (This is an SQL Server error code)

...

We handle the "General Network Error" as a timeout exception too. It only occurs under rare circumstances e.g. when your update/insert/delete query will raise a long running trigger.

Answer 3

Updated for c# 6:

    try
    {
        // some code
    }
    catch (SqlException ex) when (ex.Number == -2)  // -2 is a sql timeout
    {
        // handle timeout
    }

Very simple and nice to look at!!

Answer 4

Whats the value for the SqlException.ErrorCode property? Can you work with that?

When having timeouts, it may be worth checking the code for -2146232060.

I would set this up as a static const in your data code.