问题
I am executing a command in this way :
var Command = new SqlCommand(cmdText, Connection, tr);
Command.ExecuteNonQuery();
In the command there is an error, however .NET does not throw any error message. How could I know that the command did not executed properly, and how to get the exception?
回答1:
You'll only get an exception in C# if your error's severity is 16 or above. If you are using a PRINT, you won't get an exception in .NET.
If you can edit the raise error code, this would cause a SqlException in C#:
RAISERROR('Some error message', 16, 1)
You can then get to each individual error in the SqlException.Errors collection.
Just a side-note - SQL Server will continue to run commands after the RAISERROR if you don't RETURN directly afterwards. If you don't return, you can get multiple errors back.
回答2:
.NET does indeed raise an error message... if the severity is 16 or above (since it throws an exception) - the message will be in the exception .Message. If you are using RAISERROR with a lower severity (or using PRINT) then you will have to subscribe to the InfoMessage event on the connection.
回答3:
Only high severity errors will be thrown back in ExecuteNonQuery. There is another scenario that I have observed with OdbcCommand.ExecuteNonQuery() method. May be this is true for SqlCommand.ExecuteNonQuery() as well. If the SQL contained in the CommandText property is a single statement (Example: INSERT INTO table (col1,col2) VALUES (2,'ABC'); ) and if there is a foreign key violation or primary key violation in the above statement ExecuteNonQuery will throw an exception. However, if your CommandText is a batch where you have more than one SQL Statements seperated by semi colon (Like Several INSERTS or UPDATES) and if one of them fails ExecuteNonQuery does not throw an exception back. You need to be explicitly checking for the number of records affected returned by the method. Simply putting the code in a try{}Catch{} wont help.
回答4:
Try the below.
PS: Just because you use a transaction, doesn't mean you can neglect handling exceptions and rollbacks.
public static void MessageEventHandler( object sender, SqlInfoMessageEventArgs e ) {
foreach( SqlError error in e.Errors ) {
Console.WriteLine("problem with sql: "+error);
throw new Exception("problem with sql: "+error);
}
}
public static int executeSQLUpdate(string database, string command) {
SqlConnection connection = null;
SqlCommand sqlcommand = null;
int rows = -1;
try {
connection = getConnection(database);
connection.InfoMessage += new SqlInfoMessageEventHandler( MessageEventHandler );
sqlcommand = connection.CreateCommand();
sqlcommand.CommandText = command;
connection.Open();
rows = sqlcommand.ExecuteNonQuery();
} catch(Exception e) {
Console.Write("executeSQLUpdate: problem with command:"+command+"e="+e);
Console.Out.Flush();
throw new Exception("executeSQLUpdate: problem with command:"+command,e);
} finally {
if(connection != null) { connection.Close(); }
}
return rows;
}
And this is proper transaction handling:
//public static void ExecuteInTransaction(Subtext.Scripting.SqlScriptRunner srScriptRunner)
public override void ExecuteInTransaction(string strSQL)
{
System.Data.Odbc.OdbcTransaction trnTransaction = null;
try
{
System.Threading.Monitor.Enter(m_SqlConnection);
if (isDataBaseConnectionOpen() == false)
OpenSQLConnection();
trnTransaction = m_SqlConnection.BeginTransaction();
try
{
/*
foreach (Subtext.Scripting.Script scThisScript in srScriptRunner.ScriptCollection)
{
System.Data.Odbc.OdbcCommand cmd = new System.Data.Odbc.OdbcCommand(scThisScript.ScriptText, m_sqlConnection, trnTransaction);
cmd.ExecuteNonQuery();
}
*/
// pfff, mono C# compiler problem...
// System.Data.Odbc.OdbcCommand cmd = new System.Data.Odbc.OdbcCommand(strSQL, m_SqlConnection, trnTransaction);
System.Data.Odbc.OdbcCommand cmd = this.m_SqlConnection.CreateCommand();
cmd.CommandText = strSQL;
cmd.ExecuteNonQuery();
trnTransaction.Commit();
} // End Try
catch (System.Data.Odbc.OdbcException exSQLerror)
{
Log(strSQL);
Log(exSQLerror.Message);
Log(exSQLerror.StackTrace);
trnTransaction.Rollback();
} // End Catch
} // End Try
catch (Exception ex)
{
Log(strSQL);
Log(ex.Message);
Log(ex.StackTrace);
} // End Catch
finally
{
strSQL = null;
if(m_SqlConnection.State != System.Data.ConnectionState.Closed)
m_SqlConnection.Close();
System.Threading.Monitor.Exit(m_SqlConnection);
} // End Finally
} // End Sub ExecuteInTransaction
回答5:
Inspired by the work of M Hassan, Stefan Steiger, and Mark Gravell in this thread, here is a minimum proof-of-concept example of what is going on here:
private static void DoSql()
{
// Errors of severity level of 10 or less
// will NOT bubble up to .Net as an Exception to be caught in the usual way
const string sql = @"RAISERROR('A test error message of low severity', 10, 1)";
using (SqlConnection conn = new SqlConnection(myConnString))
{
conn.Open();
// Hook up my listener to the connection message generator
conn.InfoMessage += new SqlInfoMessageEventHandler(MySqlMessageHandler);
using (SqlCommand cmd = new SqlCommand(sql, conn))
{
cmd.ExecuteNonQuery();
// code happily carries on to this point
// despite the sql Level 10 error that happened above
}
}
}
private static void MySqlMessageHandler(object sender, SqlInfoMessageEventArgs e)
{
// This gets all the messages generated during the execution of the SQL,
// including low-severity error messages.
foreach (SqlError err in e.Errors)
{
// TODO: Something smarter than this for handling the messages
MessageBox.Show(err.Message);
}
}
回答6:
You catch the SqlException using try/catch
try
{
//.......
Command.ExecuteNonQuery();
}
catch (SqlException ex)
{
log (SqlExceptionMessage(ex).ToString());
}
The following Method Catch details of SqlException which can be logged or displayed to user
public StringBuilder SqlExceptionMessage(SqlException ex)
{
StringBuilder sqlErrorMessages = new StringBuilder("Sql Exception:\n");
foreach (SqlError error in ex.Errors)
{
sqlErrorMessages.AppendFormat("Mesage: {0}\n", error.Message)
.AppendFormat("Severity level: {0}\n", error.Class)
.AppendFormat("State: {0}\n", error.State)
.AppendFormat("Number: {0}\n", error.Number)
.AppendFormat("Procedure: {0}\n", error.Procedure)
.AppendFormat("Source: {0}\n", error.Source)
.AppendFormat("LineNumber: {0}\n", error.LineNumber)
.AppendFormat("Server: {0}\n", error.Server)
.AppendLine(new string('-',error.Message.Length+7));
}
return sqlErrorMessages;
}
The Generated message look like:
Sql Exception:
Mesage: Error converting data type nvarchar to datetime.
Severity level: 16
State: 5
Number: 8114
Procedure: Sales by Year
Source: .Net SqlClient Data Provider
LineNumber: 0
Server: myserver
-------------------------------------------------------
来源：https://stackoverflow.com/questions/7024109/how-can-i-get-an-error-message-that-happens-when-using-executenonquery