SqlException Class

Definition

The exception that is thrown when SQL Server returns a warning or error. This class cannot be inherited.

public sealed class SqlException : System.Data.Common.DbException
[System.Serializable]
public sealed class SqlException : System.Data.Common.DbException
type SqlException = class
    inherit DbException
[<System.Serializable>]
type SqlException = class
    inherit DbException
Public NotInheritable Class SqlException
Inherits DbException
Inheritance
SqlException
Attributes

Examples

The following example generates a SqlException and then displays the exception.

using Microsoft.Data.SqlClient;
using System.Text;

class Program
{
    static void Main()
    {
        string s = GetConnectionString();
        ShowSqlException(s);
        Console.ReadLine();
    }
    public static void ShowSqlException(string connectionString)
    {
        string queryString = "EXECUTE NonExistantStoredProcedure";
        StringBuilder errorMessages = new StringBuilder();

        using (SqlConnection connection = new SqlConnection(connectionString))
        {
            SqlCommand command = new SqlCommand(queryString, connection);
            try
            {
                command.Connection.Open();
                command.ExecuteNonQuery();
            }
            catch (SqlException ex)
            {
                for (int i = 0; i < ex.Errors.Count; i++)
                {
                    errorMessages.Append("Index #" + i + "\n" +
                        "Message: " + ex.Errors[i].Message + "\n" +
                        "LineNumber: " + ex.Errors[i].LineNumber + "\n" +
                        "Source: " + ex.Errors[i].Source + "\n" +
                        "Procedure: " + ex.Errors[i].Procedure + "\n");
                }
                Console.WriteLine(errorMessages.ToString());
            }
        }
    }

    static private string GetConnectionString()
    {
        // To avoid storing the connection string in your code, 
        // you can retrieve it from a configuration file.
        return "Data Source=(local);Initial Catalog=AdventureWorks;"
            + "Integrated Security=SSPI";
    }
}

Remarks

This class is created whenever the .NET Framework Data Provider for SQL Server encounters an error generated from the server. (Client side errors are thrown as standard common language runtime exceptions.) SqlException always contains at least one instance of SqlError.

Messages that have a severity level of 10 or less are informational and indicate problems caused by mistakes in information that a user has entered. Severity levels from 11 through 16 are generated by the user, and can be corrected by the user. Severity levels from 17 through 25 indicate software or hardware errors. When a level 17, 18, or 19 error occurs, you can continue working, although you might not be able to execute a particular statement.

The SqlConnection remains open when the severity level is 19 or less. When the severity level is 20 or greater, the server ordinarily closes the SqlConnection. However, the user can reopen the connection and continue. In both cases, a SqlException is generated by the method executing the command.

For information about the warning and informational messages sent by SQL Server, see Database Engine Events and Errors. The SqlException class maps to SQL Server severity.

The following is general information on handling exceptions. Your code should catch exceptions to prevent the application from crashing and to allow displaying a relevant error message to the user. You can use database transactions to ensure that the data is consistent regardless of what happens in the client application (including a crash). Features like System.Transaction.TransactionScope or the BeginTransaction method (in System.Data.OleDb.OleDbConnection, System.Data.ODBC.ODBCConnection, and Microsoft.Data.SqlClient.SqlConnection) ensure consistent data regardless of exceptions raised by a provider. Transactions can fail, so catch failures and retry the transaction.

Note that beginning with .NET Framework 4.5, SqlException can return an inner Win32Exception.

The exception class of a .NET Framework data provider reports provider-specific errors. For example System.Data.Odbc has OdbcException, System.Data.OleDb has OleDbException, and Microsoft.Data.SqlClient has SqlException. For the best level of error detail, catch these exceptions and use the members of these exception classes to get details of the error.

In addition to the provider-specific errors, .NET Framework data provider types can raise .NET Framework exceptions such as System.OutOfMemoryException and System.Threading.ThreadAbortException. Recovery from these exceptions may not be possible.

Bad input can cause a .NET Framework data provider type to raise an exception such as System.ArgumentException or System.IndexOutOfRangeException. Calling a method at the wrong time can raise System.InvalidOperationException.

So, in general, write an exception handler that catches any provider specific exceptions as well as exceptions from the common language runtime. These can be layered as follows:

try {  
   // code here  
}  
catch (SqlException odbcEx) {  
   // Handle more specific SqlException exception here.  
}  
catch (Exception ex) {  
   // Handle generic ones here.  
}  

Or:

try {  
   // code here  
}  
catch (Exception ex) {  
   if (ex is SqlException) {  
      // Handle more specific SqlException exception here.  
   }  
   else {  
      // Handle generic ones here.  
   }  
}  

It is also possible for a .NET Framework data provider method call to fail on a thread pool thread with no user code on the stack. In this case, and when using asynchronous method calls, you must register the UnhandledException event to handle those exceptions and avoid application crash.

Properties

Class

Gets the severity level of the error returned from the .NET Framework Data Provider for SQL Server.

ClientConnectionId

Represents the client connection ID. For more information, see Data Tracing in ADO.NET.

Errors

Gets a collection of one or more SqlError objects that give detailed information about exceptions generated by the .NET Framework Data Provider for SQL Server.

LineNumber

Gets the line number within the Transact-SQL command batch or stored procedure that generated the error.

Number

Gets a number that identifies the type of error.

Procedure

Gets the name of the stored procedure or remote procedure call (RPC) that generated the error.

Server

Gets the name of the computer that is running an instance of SQL Server that generated the error.

Source

Gets the name of the provider that generated the error.

State

Gets a numeric error code from SQL Server that represents an error, warning or "no data found" message. For more information about how to decode these values, see Database Engine Events and Errors.

Methods

GetObjectData(SerializationInfo, StreamingContext)

Sets the SerializationInfo with information about the exception.

ToString()

Returns a string that represents the current SqlException object, and includes the client connection ID (for more information, see ClientConnectionId).

Applies to

See also