luxspes said:
Copy&Pasted from (A Gentle Introduction to ADO.NET 2.0 Trace Facilities):
Using Tracing to Debug a Parameter Binding Problem
Now that we've gone through the quick overview of tracing, I'd like to
present a simple use case. I'd often use ODBC trace to do problem
determination when an application would "eat" a rich error message and
produce a polite but fairly "information-free" message. Such application
code would look like this:
string s = GetConnectionStringFromConfigFile();
using (SqlConnection conn = new SqlConnection(s))
using (SqlCommand cmd = new SqlCommand(
"select * from authors where au_id = @auid", conn))
{
// the error is hardcoded here but could have come from suboptimal
// editing in a graphic user interface
cmd.Parameters.Add("@auid", SqlDbType.Int);
cmd.Parameters[0].Value = 123456789;
SqlDataReader rdr = null;
try {
// some code that could fail goes here
conn.Open();
rdr = cmd.ExecuteReader();
while (rdr.Read())
Console.WriteLine(rdr[0]);
rdr.Close();
}
catch (Exception e) {
MessageBox.Show("polite error message");
}
}
In this case, the error was caused by a parameter type mismatch, and the
person diagnosing the error might not have access to the source code of
the program. Turning on the trace, we'll see output like this:
"enter_01 <sc.SqlCommand.ExecuteReader|API> 1#"
"<sc.SqlCommand.get_Connection|API> 1#"
"<sc.SqlCommand.get_Connection|API> 1#"
"<sc.TdsParser.CreateSession|ADV> 1# created session 3"
"<sc.TdsParserSessionPool.CreateSession|ADV> 1# adding session 3 to pool"
"<sc.TdsParserSessionPool.GetSession|ADV> 1# using session 3"
"<sc.TdsParser.GetSession|ADV> 1# getting session 3 from pool"
"<sc.SqlCommand.ExecuteReader|INFO> 1# Command executed as RPC."
"<sc.SqlCommand.get_Connection|API> 1#"
"leave_01"
"enter_01 <sc.SqlDataReader.Read|API> 1#"
"<sc.SqlError.SqlError|ERR> infoNumber=245 errorState=1 errorClass=16
errorMessage='Syntax error converting the varchar value '172-32-1176' to a
column of data type int.' procedure='' lineNumber=1"
"leave_01"
This shows us directly that there is a parameter value mismatch. The
sample and the trace file are provided in the article code. Note that
the trace file is much more compact in this case because we're only
tracing with the System.Data.1 provider.
