How to display TextBox/ComboBox value from database table?

Question

There is a database table TableUser, and there are four fields: FirstName, LastName, Country, State. Actually, there is another field Username, which does not require user to provide, it is ENvironment.Name

When user submits his/her information, first three fields are required, and State is optional.

Now in another form, user wants to update his/her information (It is guaranteed that the user is in database).

Two parts of question:
How to display the record value back into TextBox/ComboBox?
When user updates his/her information, how to write the code to update information in database? It is same that first three fields are required and State is optional.

Thanks.

    private void ChildForm1_Load(object sender, EventArgs e)
           {


               OdbcConnection Cn = new OdbcConnection(GlobalVariables.DatabaseConnectionString);
               Cn.Open();

 string query = "SELECT * from TableUser WHERE Username = '" + ENvironment.Name + "'";
 //It is guaranteed that there is one record

 TextboxFirstName.Text = FirstName from returned query; there is a value
 TextboxLastName.Text = LastName from returned query; there is a value

 ComboBoxCountry.Text = Country from returned query; there is a value
 ComboBoxState.Text = State from returned query; It may be missing/null


               Cn.Close();


           }

Answer 1

Hi VAer-4038,
For question1, you can try the following the code:

using (OdbcConnection connection = new OdbcConnection())  
 {  
        connection.ConnectionString = "Your connectionString";  
        connection.Open();  
        OdbcCommand command = new OdbcCommand("SELECT * from TableUser WHERE Username = '" + ENvironment.Name + "'", connection );  
        // Execute the DataReader and access the data.  
        OdbcDataReader dr = command.ExecuteReader();  
        while (dr.Read())  
        {  
           TextboxFirstName.Text = dr["FirstName"].ToString();  
           TextboxLastName.Text = dr["LastName "].ToString();  
        }  
}  

For question2, you can use OdbcCommand.ExecuteNonQuery method to execute an SQL statement against the connection.
And here is code example i this document you can refer to.
Best Regards,
Daniel Zhang

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