问题
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!
回答1:
Execute SELECT 1 and check if ExecuteScalar returns 1.
回答2:
I have had a difficulty with the EF when the connection the server is stopped or paused, and I raised the same question. So for completeness to the above answers here is the code.
/// <summary>
/// Test that the server is connected
/// </summary>
/// <param name="connectionString">The connection string</param>
/// <returns>true if the connection is opened</returns>
private static bool IsServerConnected(string connectionString)
{
using (SqlConnection connection = new SqlConnection(connectionString))
{
try
{
connection.Open();
return true;
}
catch (SqlException)
{
return false;
}
}
}
回答3:
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);
}
回答4:
Wouldn't establishing a connection to the database do this for you? If the database isn't up you won't be able to establish a connection.
回答5:
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.
回答6:
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.]
回答7:
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
}
回答8:
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.
回答9:
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.
来源：https://stackoverflow.com/questions/2440060/whats-the-best-way-to-test-sql-server-connection-programmatically