What's the best way to test SQL Server connect

Question

I need to develop a single routine that will be fired each 5 minutes to check if a list of SQL Servers (10 to 12) are up and running.

I can try to obtain a simple query in each one of the servers but this means that I have to create a table, view or stored procedure in every server, even if I use any already made SP I need to have a registered user in each server too. The servers are not in the same physical location so having those requirements would be a complex task. Is there a way to simply "ping" from C# one SQL Server?

Thanks in advance!

Answer 1

Look for an open listener on port 1433 (the default port). If you get any response after creating a tcp connection there, the server's probably up.

Answer 2

Similar to the answer offered by Andrew, but I use:

Select GetDate() as CurrentDate

This allows me to see if the SQL Server and the client have any time zone difference issues, in the same action.

Answer 3

For what Joel Coehorn suggested, have you already tried the utility named tcping. I know this is something you are not doing programmatically. It is a standalone executable which allows you to ping every specified time interval. It is not in C# though. Also..I am not sure If this would work If the target machine has firewall..hmmm..

[I am kinda new to this site and mistakenly added this as a comment, now added this as an answer. Let me know If this can be done here as I have duplicate comments (as comment and as an answer) here. I can not delete comments here.]

Answer 4

public static class SqlConnectionExtension
{
    #region Public Methods

    public static bool ExIsOpen(this SqlConnection connection, MessageString errorMsg)
    {
        if (connection == null) return false;
        if (connection.State != ConnectionState.Open)
        {
            try
            {
                connection.Open();
            }
            catch (Exception ex) { errorMsg.Append(ex.ToString()); }
        }
        return true;
    }

    public static bool ExIsReady(this SqlConnection connction, MessageString errorMsg)
    {
        if (ExIsOpen(connction, errorMsg) == false) return false;
        try
        {
            using (SqlCommand command = new SqlCommand("select 1", connction))
            using (SqlDataReader reader = command.ExecuteReader())
                if (reader.Read()) return true;
        }
        catch (Exception ex) { errorMsg.Append(ex.ToString()); }
        return false;
    }

    #endregion Public Methods
}



public class MessageString : IDisposable
{
    #region Protected Fields

    protected StringBuilder _messageBuilder = new StringBuilder();

    #endregion Protected Fields

    #region Public Constructors

    public MessageString()
    {
    }

    public MessageString(int capacity)
    {
        _messageBuilder.Capacity = capacity;
    }

    public MessageString(string value)
    {
        _messageBuilder.Append(value);
    }

    #endregion Public Constructors

    #region Public Properties

    public int Length {
        get { return _messageBuilder.Length; }
        set { _messageBuilder.Length = value; }
    }

    public int MaxCapacity {
        get { return _messageBuilder.MaxCapacity; }
    }

    #endregion Public Properties

    #region Public Methods

    public static implicit operator string(MessageString ms)
    {
        return ms.ToString();
    }

    public static MessageString operator +(MessageString ms1, MessageString ms2)
    {
        MessageString ms = new MessageString(ms1.Length + ms2.Length);
        ms.Append(ms1.ToString());
        ms.Append(ms2.ToString());
        return ms;
    }

    public MessageString Append<T>(T value) where T : IConvertible
    {
        _messageBuilder.Append(value);
        return this;
    }

    public MessageString Append(string value)
    {
        return Append<string>(value);
    }

    public MessageString Append(MessageString ms)
    {
        return Append(ms.ToString());
    }

    public MessageString AppendFormat(string format, params object[] args)
    {
        _messageBuilder.AppendFormat(CultureInfo.InvariantCulture, format, args);
        return this;
    }

    public MessageString AppendLine()
    {
        _messageBuilder.AppendLine();
        return this;
    }

    public MessageString AppendLine(string value)
    {
        _messageBuilder.AppendLine(value);
        return this;
    }

    public MessageString AppendLine(MessageString ms)
    {
        _messageBuilder.AppendLine(ms.ToString());
        return this;
    }

    public MessageString AppendLine<T>(T value) where T : IConvertible
    {
        Append<T>(value);
        AppendLine();
        return this;
    }

    public MessageString Clear()
    {
        _messageBuilder.Clear();
        return this;
    }

    public void Dispose()
    {
        _messageBuilder.Clear();
        _messageBuilder = null;
    }

    public int EnsureCapacity(int capacity)
    {
        return _messageBuilder.EnsureCapacity(capacity);
    }

    public bool Equals(MessageString ms)
    {
        return Equals(ms.ToString());
    }

    public bool Equals(StringBuilder sb)
    {
        return _messageBuilder.Equals(sb);
    }

    public bool Equals(string value)
    {
        return Equals(new StringBuilder(value));
    }

    public MessageString Insert<T>(int index, T value)
    {
        _messageBuilder.Insert(index, value);
        return this;
    }

    public MessageString Remove(int startIndex, int length)
    {
        _messageBuilder.Remove(startIndex, length);
        return this;
    }

    public MessageString Replace(char oldChar, char newChar)
    {
        _messageBuilder.Replace(oldChar, newChar);
        return this;
    }

    public MessageString Replace(string oldValue, string newValue)
    {
        _messageBuilder.Replace(oldValue, newValue);
        return this;
    }

    public MessageString Replace(char oldChar, char newChar, int startIndex, int count)
    {
        _messageBuilder.Replace(oldChar, newChar, startIndex, count);
        return this;
    }

    public MessageString Replace(string oldValue, string newValue, int startIndex, int count)
    {
        _messageBuilder.Replace(oldValue, newValue, startIndex, count);
        return this;
    }

    public override string ToString()
    {
        return _messageBuilder.ToString();
    }

    public string ToString(int startIndex, int length)
    {
        return _messageBuilder.ToString(startIndex, length);
    }

    #endregion Public Methods
}

Answer 5

See the following project on GitHub: https://github.com/ghuntley/csharp-mssql-connectivity-tester

try
{
    Console.WriteLine("Connecting to: {0}", AppConfig.ConnectionString);
    using (var connection = new SqlConnection(AppConfig.ConnectionString))
    {
        var query = "select 1";
        Console.WriteLine("Executing: {0}", query);

        var command = new SqlCommand(query, connection);

        connection.Open();
        Console.WriteLine("SQL Connection successful.");

        command.ExecuteScalar();
        Console.WriteLine("SQL Query execution successful.");
    }
}
catch (Exception ex)
{
    Console.WriteLine("Failure: {0}", ex.Message);
}

Answer 6

Connecting to mssql via C# is very problematic.

The handles will not be consistent once we connect, although we have close the connection after connect.

I did read somewhere it was .Net 4.0 issue, and if you use .Net 3.5 it should be ok.