Develop Reference

C# Connection mysql with self signed

Is self signed certificate disrupting connection to mysql?
I already give action crud in data and grant access to administration.
but the connection still got error.
Unable to connect to any of the specified MySQL hosts
my team connection like this:
Catalog=devbaf;User Id=userclient;password=client123
connection code:
try
{
string constring = "SERVER=123.45.678.9;DATABASE=devbaf;User Id=backendsystem;PASSWORD=1q2w3e4r5t;";
using (MySqlConnection con = new MySqlConnection(constring))
{
using (MySqlCommand cmd = new MySqlCommand("SELECT * FROM users"))
{
using (MySqlDataAdapter sda = new MySqlDataAdapter())
{
cmd.Connection = con;
sda.SelectCommand = cmd;
using (DataTable dt = new DataTable())
{
sda.Fill(dt);
gvtest.DataSource = dt;
gvtest.DataBind();
}
}
}
}
}
catch (Exception e)
{
Response.Write(e.Message.ToString());
}
explanation problem:
I make a database in local server, so my friend can access to it to insert data. but when he make a connection script it wont connect to my database but can connect to server. He already tries to move some file to the server and it works,but the connection to database wont connect. i don't have an experience for this coz im php programmer not c# programmer. hope my explanation is clear.

I have found your error message like trying to connect the host but in your connection string is missing the MySQL server name or host address. I hope if you add the MySQL hostname or server address to your connection. it will fix your issue.
you can try this
string connectionString ="SERVER=servername; DATABASE=databasename; User Id=userid; PASSWORD=password;";

Open database into application c#

I have added a SQL Server .mdf database file to my C# application, but when I try to connect with this code, the program causes a connection error.
CODE:
DataSet data;
string con = "Data Source=dbinterno.mdf;";
string queryString = "Select * FROM Dati";
try
{
using (SqlConnection connection = new SqlConnection(con))
{
connection.Open();
SqlDataAdapter adapter = new SqlDataAdapter();
SqlCommand command = new SqlCommand(queryString, connection);
command.ExecuteNonQuery();
data = new DataSet();
adapter.Fill(data);
MessageBox.Show(data.ToString());
connection.Close();
}
}
catch
{
MessageBox.Show("\n Problemi di connessione al database");
}
The error is:
ERROR IMAGE

Here are a couple observations:
Your connection string will need to be modified. Try using
string con = "Server=myServerAddress;Database=myDataBase;Trusted_Connection=True;";
using Windows Authentication or this:
string con = "Server=myServerAddress;Database=myDataBase;User Id=myUsername;
Password=myPassword;"; using standard security, Source: connectionstrings.com. This should be managed some other way than in code as well. Desktop applications can be de-compiled, and if the password changes, you would need a rebuild. In a ASP.NET application, Microsoft advises to use a web.config file or in the windows registry using a custom subkey.
You will want to use ExecuteReader() for a SELECT statement as ExecuteNonQuery() will not return a result set. See this answer that describes the differences in the types of SQL Server methods
you don't need connection.Close();, the using statement will handle that.

Getting Error while connecting to DB using c#

Is there anything wrong with this code? Please help me out.
protected void Button_Click(object sender, EventArgs e)
{
string cs = "Data Source=SFSIND0402;Initial Catalog=TestDB;Integrated Security=SSPI;Provider=Microsoft.ACE.OLEDB.12.0";
OleDbConnection conn = new OleDbConnection(cs);
conn.Open();
OleDbCommand insert = conn.CreateCommand();
insert.CommandText="insert into Employee(ID, Name, Sex, Salary) values('003','Vedpathi','M',25000)";
insert.Connection = conn;
insert.ExecuteNonQuery();
conn.Close();
}
I am getting the following error:
Multiple-step OLE DB operation generated errors. Check each OLE DB status value, if available. No work was done
(on line 22:conn.Open();)

When connecting to an MS SQL database, use the MS SQL providers:
using (var connection = new SqlConnection(connectionString))
{
connection.Open();
var cmd = new SqlCommand(commandText, connection);
cmd.ExecuteNonQuery();
}

In addition to the solution Luaan mentioned, you should store your connection string in the config file of the app and also encrypt it.
Even if you use SSL encryption when communicating with the DB, an ill-indended person can extract the string variables, if he / she runs the application on his / her machine.

[ODBC Firebird Driver][Firebird]attempted update during read-only transaction

I am getting above error during an insert query firebird,
Following is snippet of my code, i use odbc connection to perform and insert command
[ODBC Firebird Driver][Firebird]attempted update during read-only transaction
using (OdbcConnection cn = new OdbcConnection(string.Format("dsn={0};UID={1};PWD={2};", dsn, user, pwd)))
{
cn.Open();
foreach (var track in tracking)
{
string insertSQL = string.Format("INSERT INTO SHIPPINGIMPORT (TRACKINGNUM, SHIPCARTONID) VALUES ('{0}','{1}')",track.TrackingNum, track.CartonId);
using (OdbcCommand cmd = new OdbcCommand(insertSQL, cn))
{
cmd.CommandType = CommandType.Text;
cmd.ExecuteNonQuery();
}
}
}

Since I am using odbc connection, the fault was actually in the odbc connection configuration. You simply need to un-check the read (default write). Now it works like a charm. Hope this helps someone.

MySqlConnection in C# not working

My connection to my database is not working. It tries to load for a long time then says the connection failed. All i want to do is access the database and print out a name. I am brand new to this but here is what i have so far:
string connectionstring = "uid=user;server=it.et.byu.edu;port=xxxxx;database=database;password=password;";
MySqlConnection connection = new MySqlConnection(connectionstring);
connection.Open();
MySqlCommand cmd = new MySqlCommand("SELECT username FROM Users WHERE username='george'", connection);
try
{
MySqlDataReader rdr = cmd.ExecuteReader();
while (rdr.Read())
{
Console.WriteLine(rdr.GetString(0));
}
rdr.Close();
}
connection.Close();

Check your connection string and make sure you can connect/manipulate your MYSQL database if you are using XAMPP or other Mysql Tools using your credentials(uid,password).
For introduction this might help you :
ADO.NET With MySQL and MSDE
Connection strings for MySQL
Best Regards