I write a little Chat Application. To save some infos like Username and Password I store the Data in an SQL-Compact 3.5 SP1 Database.
Everything working fine, but If another (the same .exe on the same machine) Client want to access the Service. It came an EndpointNotFound exception, from the ServiceReference.Class.Open() at the Second Client.
So i remove the CE Data Access Code and I get no Error (with an if (false))
Where is the Problem?
I googled for this, but no one seems the same error I get :(
SOLUTION
I used the wrapper in
http://csharponphone.blogspot.com/2007/01/keeping-sqlceconnection-open-and-thread.html
for threat safty, and now it works :)
Client Code:
public test()
{
var newCompositeType = new Client.ServiceReference1.CompositeType();
newCompositeType.StringValue = "Hallo" + DateTime.Now.ToLongTimeString();
newCompositeType.Save = (Console.ReadKey().Key == ConsoleKey.J);
ServiceReference1.Service1Client sc = new Client.ServiceReference1.Service1Client();
sc.Open();
Console.WriteLine("Save " + newCompositeType.StringValue);
sc.GetDataUsingDataContract(newCompositeType);
sc.Close();
}
Server Code
public CompositeType GetDataUsingDataContract(CompositeType composite)
{
if (composite.Save)
{
SqlCeConnection con = new SqlCeConnection(Properties.Settings.Default.Con);
con.Open();
var com = con.CreateCommand();
com.CommandText = "SELECT * FROM TEST";
SqlCeResultSet result = com.ExecuteResultSet(ResultSetOptions.Scrollable | ResultSetOptions.Updatable);
var rec = result.CreateRecord();
rec["TextField"] = composite.StringValue;
result.Insert(rec);
result.Close();
result.Dispose();
com.Dispose();
con.Close();
con.Dispose();
}
return composite;
}
You're not closing the connection before disposing the con object.
Try:
con.Close();
con.Dispose();
Could be an exception occuring during the service initialisation when the second client connects. Debug the service at the same time as running the second exe,
Set exception behaviour in VS to break when Common Language Runtime Exceptions are thrown as well as when they're unhandled and you'll see the error.
As tomlog's answer states - it could be because you're not closing the connection properly.
I used the wrapper in http://csharponphone.blogspot.com/2007/01/keeping-sqlceconnection-open-and-thread.html for threat safty, and now it works :)
Related
I have read the numerous posts on why you should give the using statement preference over manually doing .Open() then .Close() and finally .Dispose().
When I initially wrote my code, I had something like this:
private static void doIt(string strConnectionString, string strUsername)
{
SqlConnection conn = new SqlConnection(strConnectionString);
try
{
conn.Open();
string strSqlCommandText = $"CREATE USER {strUsername} for LOGIN {strUsername} WITH DEFAULT SCHEMA = [dbo];";
SqlCommand sqlCommand = new SqlCommand(strSqlCommandText, conn);
var sqlNonReader = sqlCommand.ExecuteNonQuery();
if (sqlNonReader == -1) Utility.Notify($"User Added: {strUsername}");
}
catch (Exception ex)
{
Console.WriteLine($"Error: {ex.Message}");
}
finally
{
conn.Close();
conn.Dispose();
}
}
and this works... no problem. but only ONCE.
so, if I do something like this:
private static void doItLots(string strConnectionString, string strUsername)
{
for(int i=0; i<10; i++)
{
doIt(strConnectionString, $"{strUsername}_{i}");
}
}
it works the FIRST time when i=0, but any subsequent iterations fail with Cannot open database "myDbName" requested by the login. The login failed.
However, if I go back and comment out the conn.Dispose(); line, then it works fine on all iterations.
The problem is simply that if I want to do the .Dispose() part outside of the method, then I am forced to pass a SqlConnection object instead of simply passing the credentials, potentially making my code a bit less portable and then I need to keep the connection around longer as well. I was always under the impression that you want to open and close connections quickly but clearly I'm misunderstanding the way the .Dispose() command works.
As I stated at the outset, I also tried doing this with using like this...
private static void doIt(string strConnectionString, string strUsername)
{
using (SqlConnection conn = new SqlConnection(strConnectionString))
{
try
{
conn.Open();
string strSqlCommandText = $"CREATE USER {strUsername} for LOGIN {strUsername} WITH DEFAULT SCHEMA = [dbo];";
SqlCommand sqlCommand = new SqlCommand(strSqlCommandText, conn);
var sqlNonReader = sqlCommand.ExecuteNonQuery();
if (sqlNonReader == -1) Utility.Notify($"User Added: {strUsername}");
}
catch (Exception ex)
{
Console.WriteLine($"Error: {ex.Message}");
}
finally
{
conn.Close();
}
}
}
and this does the exact same thing as the initial code with .Dispose() called manually.
Any help here would be greatly appreciated. I'd love to convert to the using statements but having trouble figuring out how to write reusable methods that way...
UPDATE:
I have narrowed it down a bit. The issue is NOT the iterations or making the calls over-and-over again. But I am still getting an access error. Here is the code:
string strConnectionString = $#"Data Source={StrSqlServerDataSource};Initial Catalog={StrDatabaseName};User id={StrSqlServerMasterUser};Password={StrSqlServerMasterPassword}";
using (SqlConnection connUserDb = new SqlConnection(strConnectionString))
{
try
{
Utility.Notify($"Connection State: {connUserDb.State.ToString()}"); // Responds as 'Closed'
connUserDb.Open(); // <-- throws error
Utility.Notify($"Connection State: {connUserDb.State.ToString()}");
Utility.Notify($"MSSQL Connection Open... Adding User '{strUsername}' to Database: '{strDatabaseName}'");
string sqlCommandText =
//$#"USE {StrDatabaseName}; " +
$#"CREATE USER [{strUsername}] FOR LOGIN [{strUsername}] WITH DEFAULT_SCHEMA = [dbo]; " +
$#"ALTER ROLE [db_datareader] ADD MEMBER [{strUsername}]; " +
$#"ALTER ROLE [db_datawriter] ADD MEMBER [{strUsername}]; " +
$#"ALTER ROLE [db_ddladmin] ADD MEMBER [{strUsername}]; ";
using (SqlCommand sqlCommand = new SqlCommand(sqlCommandText, connUserDb))
{
var sqlNonReader = sqlCommand.ExecuteNonQuery();
if (sqlNonReader == -1) Utility.Notify($"User Added: {strUsername} ({sqlNonReader})");
}
result = true;
}
catch (Exception ex)
{
Utility.Notify($"Creating User and Updating Roles Failed: {ex.Message}", Priority.High);
}
finally
{
connUserDb.Close();
Utility.Notify($"MSSQL Connection Closed");
}
}
return result;
}
The error I am getting here is: Cannot open database requested by the login. The login failed.
One clue I have is that prior to this, I was running this same code with two changes:
1) uncommented the USE statement in the sqlCommandText
2) connected to the Master database instead
When I did that, it didn't work either, and instead I got this error: The server principal is not able to access the database under the current security context.
If I go into SSMS and review the MasterUser they are listed as db_owner and I can perform any activities I want, including running the command included in the code above.
I rewrote all the code to make use of a single connection per the recommendations here. After running into the "server principal" error, I added one more connection to attempt to directly connect to this database rather than the master.
UPDATE 2:
Here is another plot twist...
This is working from my local computer fine (now). But, not (always) working when run from an Azure Webjob that targets an Amazon Web Services (AWS) Relational Database Server (RDS) running MSSQL.
I will have to audit the git commits tomorrow, but as of 5p today, it was working on BOTH local and Azure. After the last update, I was able to test local and get it to work, but when run on Azure Webjob it failed as outlined above.
SqlConnection implements IDisposable. You don't call dispose or close.
try{
using (SqlConnection conn = new SqlConnection(strConnectionString))
{
conn.Open();
string strSqlCommandText = $"CREATE USER {strUsername} for LOGIN {strUsername} WITH DEFAULT SCHEMA = [dbo];";
SqlCommand sqlCommand = new SqlCommand(strSqlCommandText, conn);
var sqlNonReader = sqlCommand.ExecuteNonQuery();
if (sqlNonReader == -1) Utility.Notify($"User Added: {strUsername}");
}}
catch (Exception ex)
{
Console.WriteLine($"Error: {ex.Message}");
}
I got a web service running on c# but recently, something strange happened. Even when I query from a simple table with only 1 value like this:
string str = "";
using (SqlConnection connection = new SqlConnection(ConfigurationSettings.AppSettings["Main.ConnectionStringTD"]))
{
connection.Open();
try
{
SqlCommand selectCommand = new SqlCommand
{
CommandType = CommandType.Text,
Connection = connection,
CommandText = "select Version from TN_Version"
};
str = selectCommand.ExecuteScalar().ToString();
}
catch (Exception exception)
{
str = "ERROR:" + exception.Message + "_" + exception.InnerException.Message;
Console.WriteLine(exception.Message ?? "");
}
return str;
}
This always returns correct value when I debug on local but an error message returned whenever I publish this service on host and execute it:
There is no row at position 0.
It's really strange cuz this is a simple table and absolute nothing changes or delete its value...
Error
And I have to execute the service 3 or 4 times until it gets me the correct value:
<string xmlns="http://webservice.com/">6.7</string>
Please, someone helps me, this have been bugging me to no end. Thanks you so much (really)
The error message simply means that no rows were returned by your query. so maybe, after you hosted the app, either IIS or a firewall causing this problem in the connection. Check with the firewall turned off and check the rights of your IIS user account.
For the past month I've been getting data with a C# program in tandem with a company's API. Just yesterday all the sudden it would no longer work, even though I haven't changed the code at all. Here's the code:
public string GetMatchCode()
{
//this could be loaded from config file or other source
string connectString = "Server=123.123.1.23;Database=blah_users;Uid=blah_data;Pwd=blahblah;";
string sql = "SELECT MAX(match_id) FROM `data_blah`";
using (var connect = new MySqlConnection(connectString))
using (var command = new MySqlCommand(sql, connect))
{
connect.Open();
return command.ExecuteScalar().ToString();
}
}
And I get this error:
An unhandled exception of type 'MySql.Data.MySqlClient.MySqlException' occurred in MySql.Data.dll
Additional information: Access denied for user 'blah_data'#'cpe-86-80-21-54.san.res.rr.com' (using password: YES)
Any idea what could have happened and how to fix it? The only thing I think could've happened is that my support ticket dealing with node.js compatibility was executed wrong by support employees. Thanks!
Your db user's permission has failed. The user may have been removed; the permissions may have been modified. Contact the db owner.
So it looks like you are not authenticating: Either incorrect credentials or server needs a different method. Try disabling "sslmode" like below:
public string GetMatchCode()
{
//this could be loaded from config file or other source
string connectString = "Server=123.123.1.23;Database=blah_users;Uid=blah_data;Pwd=blahblah;sslmode=none;";
string sql = "SELECT MAX(match_id) FROM `data_blah`";
using (var connect = new MySqlConnection(connectString))
using (var command = new MySqlCommand(sql, connect))
{
connect.Open();
return command.ExecuteScalar().ToString();
}
}
That should do it
string sql = "SELECT MAX(match_id) FROM `data_blah`";
Isn't it supposed to be " ' " instead of " ` " surrounding "data_blah"?
How do I create a SQL Compact Edition database? I have tried to figure it out, searched the internet and I cant find it (but then again, how do you search for this?!). Here is my code so far:
checkPasswordsMatch();
SqlCEConnection myconn = new SqlCEConnection();
SqlCeCommand myCommand = new SqlCeCommand(
#"CREATE DATABASE ""pwdb.sdf"" DATABASEPASSWORD '" + textBox1.Text + "'");
myCommand.ExecuteNonQuery();
What do I put on the connection part? I dont understand.
UPDATE: I decided to create a database to incorporate with the application, and simply check if there was a value (admin Password) dedicated to the record Master.
Here is my new code:
Application.EnableVisualStyles();
Application.SetCompatibleTextRenderingDefault(false);
SqlCeConnection myconn = new SqlCeConnection("Data Source = pwdb.sdf;");
SqlCeCommand checkpass = new SqlCeCommand("SELECT * from PW WHERE Name = Master;",myconn);
try
{
myconn.Open();
}
catch (Exception ex)
{
MessageBox.Show(ex.ToString());
}
if (checkpass.ExecuteNonQuery() != null)
{
Application.Run(new enterMasterPassword());
}
else
Application.Run(new mainPassSet());
The problem is, when i execute this now, i get:
An unhandled exception of type 'System.Data.SqlServerCe.SqlCeException' occurred in System.Data.SqlServerCe.dll
Any ideas anyone??
Try using the SqlCeEngine class. With that class you can create a new database:
using (SqlCeEngine engine = new SqlCeEngine())
{
engine.LocalConnectionString = yourConnectionString;
engine.CreateDatabase();
}
Since you likely only want to create the database once you may not want to do it in your code.
A couple suggestions:
1) if you're using Visual Studio you can open the Server Explorer (Under menu View->Server Explorer) and create it there.
2) Use one of the free SQL managers like linkpad or powershell + sqlcmd (there are others)
3) or... Don't know what data model you are using but EntityFramework with "code first" will create the database for you automatically based on your connection string and how you name your data context. Since you are using the sdf tag, maybe you are using EF...
I am trying to build a .NET web application using SQL to query AS400 database. This is my first time encountering the AS400.
What do I have to install on my machine (or the AS400 server) in order to connect?
(IBM iSeries Access for Windows ??)
What are the components of the connection string?
Where can I find sample codes on building the Data Access Layer using SQL commands?
Thanks.
You need the AS400 .Net data provider. Check here:
https://www-01.ibm.com/support/docview.wss?uid=isg3T1027163
For connection string samples, check here:
https://www.connectionstrings.com/as-400/
Also, check out the redbook for code examples and getting started.
http://www.redbooks.ibm.com/redbooks/pdfs/sg246440.pdf
Following is what I did to resolve the issue.
Installed the IBM i Access for Windows. Not free
Referred the following dlls in the project
IBM.Data.DB2.iSeries.dll
Interop.cwbx.dll (If Data Queue used)
Interop.AD400.dll (If Data Queue used)
Data Access
using (iDB2Command command = new iDB2Command())
{
command.Connection = (iDB2Connection)_connection;
command.CommandType = CommandType.Text;
command.Parameters.AddWithValue(Constants.ParamInterfaceTransactionNo, 1);
command.CommandText = dynamicInsertString;
command.ExecuteScalar();
}
Connection String
<add name="InterfaceConnection"
connectionString="Data Source=myserver.mycompany.com;User ID=idbname;Password=mypassxxx;
Default Collection=ASIPTA;Naming=System"/>
UPDATE
i Access for Windows on operating systems beyond Windows 8.1 may not be supported. Try the replacement product IBM i Access Client Solutions
IBM i Access Client Solutions
As mentioned in other answers, if you have the IBM i Access client already installed, you can use the IBM.Data.DB2.iSeries package.
If you don't have the IBM i Access software, you can leverage JTOpen and use the Java drivers. You'll need the nuget package JT400.78 which will pull in the IKVM Runtime.
In my case I needed to query a DB2 database on an AS400 and output a DataTable. I found several hints and small snippets of code but nothing comprehensive so I wanted to share what I was able to build up in case it helps someone else:
using com.ibm.as400.access;
using java.sql;
var sql = "SELECT * FROM FOO WITH UR";
DriverManager.registerDriver(new com.ibm.as400.access.AS400JDBCDriver());
Connection conn = DriverManager.getConnection(
"jdbc:as400:" + ServerName + ";prompt=false", UserName, Password);
Statement stmt = conn.createStatement();
ResultSet rs = stmt.executeQuery(sql);
ResultSetMetaData md = rs.getMetaData();
int ct = md.getColumnCount();
DataTable dt = new DataTable();
for(int i=1; i<=ct; i++)
dt.Columns.Add(md.getColumnName(i));
while (rs.next())
{
var dr = dt.NewRow();
for (int i = 1; i <= ct; i++)
dr[i - 1] = rs.getObject(i);
dt.Rows.Add(dr);
}
rs.close();
The conversion from RecordSet to DataTable is a little clunky and gave me bad flashbacks to my VBScript days. Performance likely isn't blinding fast, but it works.
Extremely old question - but this is still relevant. I needed to query our AS/400 using .NET but none of the answers above worked and so I ended up creating my own method using OleDb:
public DataSet query_iseries(string datasource, string query, string[] parameterName, string[] parameterValue)
{
try
{
// Open a new stream connection to the iSeries
using (var iseries_connection = new OleDbConnection(datasource))
{
// Create a new command
OleDbCommand command = new OleDbCommand(query, iseries_connection);
// Bind parameters to command query
if (parameterName.Count() >= 1)
{
for (int i = 0; i < parameterName.Count(); i++)
{
command.Parameters.AddWithValue("#" + parameterName[i], parameterValue[i]);
}
}
// Open the connection
iseries_connection.Open();
// Create a DataSet to hold the data
DataSet iseries_data = new DataSet();
// Create a data adapter to hold results of the executed command
using (OleDbDataAdapter data_adapter = new OleDbDataAdapter(command))
{
// Fill the data set with the results of the data adapter
data_adapter.Fill(iseries_data);
}
return iseries_data;
}
}
catch (Exception ex)
{
MessageBox.Show(ex.Message);
return null;
}
}
And you would use it like so:
DataSet results = query_iseries("YOUR DATA SOURCE", "YOUR SQL QUERY", new string[] { "param_one", "param_two" }, new string[] { "param_one_value", "param_two_value"});
It returns a DataSet of the results returned. If anyone needs/wants a method for inserting/updating values within the IBM AS/400, leave a comment and I'll share...
I'm using this code and work very good for me!
Try
Dim sqltxt As String = "SELECT * FROM mplib.pfcarfib where LOTEF=" & My.Settings.loteproceso
dt1 = New DataTable
Dim ConAS400 As New OleDb.OleDbConnection
ConAS400.ConnectionString = "Provider=IBMDA400;" & _
"Data Source=192.168.100.100;" & _
"User ID=" & My.Settings.usuario & ";" & _
"Password=" & My.Settings.contrasena
Dim CmdAS400 As New OleDb.OleDbCommand(sqltxt, ConAS400)
Dim sqlAS400 As New OleDb.OleDbDataAdapter
sqlAS400.SelectCommand = CmdAS400
ConAS400.Open()
sqlAS400.Fill(dt1)
grid_detalle.DataSource = dt1
grid_detalle.DataMember = dt1.TableName
Catch ex As Exception
DevExpress.XtraEditors.XtraMessageBox.Show("Comunicación Con El AS400 No Establecida, Notifique a Informatica..", "Error", MessageBoxButtons.OK, MessageBoxIcon.Error)
Me.Close()
End Try
I recently found the ADO.Net driver available on NuGet. I have the iSeries client access installed on my PC, so I can't say if it works as a standalone, but it does connect. Theonly problem is I can't actually see any tables or procedures. I think there may be a schema or library or something I still haven't gotten down to. I will post if I find the answer. Meanwhile I can still get to the server and write most of my code with the NuGet adapter.
Check out http://asna.com/us/ as they have some development tools working with SQL and the AS400.