Question

I have developed a form that takes from user the user id and password and display the list of databases available in the local server.Now I have done it in hard coded format…like this

public void BindDBDropDown()
{
    //Create the connection object
    SqlConnection sConnection = new SqlConnection(
        ConfigurationSettings.AppSettings["ConnectionString"]);

    //To Open the connection.
    sConnection.Open();

    //Query to select the list of databases.
    string selectDatabaseNames =
        @"SELECT NAME FROM MASTER..SYSDATABASES";

    //Create the command object
    SqlCommand sCommand = 
        new SqlCommand(selectDatabaseNames, sConnection);

    try
    {
        //Create the data set 
        DataSet sDataset = new DataSet("master..sysdatabases");

        //Create the dataadapter object
        SqlDataAdapter sDataAdapter = 
            new SqlDataAdapter(selectDatabaseNames, sConnection);
        sDataAdapter.TableMappings.Add("Table", 
            "master..sysdatabases");

        //Fill the dataset
        sDataAdapter.Fill(sDataset);

        //Bind the database names in combobox
        DataViewManager dsv = sDataset.DefaultViewManager;

        //Provides the master mapping between the sourcr table 
        //and system.data.datatable
        cmbDatabases.DataSource = 
            sDataset.Tables["master..sysdatabases"];
        cmbDatabases.DisplayMember = "NAME";
        cmbDatabases.ValueMember = ("NAME");
    }
    catch(Exception ex)
    {
        //All the exceptions are handled and written in the EventLog.
        EventLog logException = new EventLog("Application");
        logException.Source = "MFDBAnalyser";
        logException.WriteEntry(ex.Message);
    }
    finally
    {
        //If connection is not closed then close the connection
        if(sConnection.State != ConnectionState.Closed)
        {
            sConnection.Close();
        }
    }
}

/// <summary>
///This function binds the names of all the tables with primary 
///keys in a dropdown cmbResults.
/// </summary>
public void GetPrimaryKeyTable()
{
    //An instance of the connection string is created to manage
    //the contents of the connection string.
    var sqlConnection = new SqlConnectionStringBuilder();
    sqlConnection.DataSource = "192.168.10.3";
    sqlConnection.UserID = "gp";
    sqlConnection.Password = "gp";
    sqlConnection.InitialCatalog = 
        Convert.ToString(cmbDatabases.SelectedValue);
    string connectionString = sqlConnection.ConnectionString;

    SqlConnection sConnection = new SqlConnection(connectionString);

    //To Open the connection.
    sConnection.Open();

    //Query to select the table_names that have PRIMARY_KEYS.
    string selectPrimaryKeys = @"
        SELECT  TABLE_NAME 
        FROM    INFORMATION_SCHEMA.TABLE_CONSTRAINTS 
        WHERE   CONSTRAINT_TYPE = 'PRIMARY KEY'
        AND     TABLE_NAME <> 'dtProperties'
        ORDER BY TABLE_NAME";

    //Create the command object
    SqlCommand sCommand = 
        new SqlCommand(selectPrimaryKeys, sConnection);

    try
    {
        //Create the dataset
        DataSet dsListOfPrimaryKeys = 
            new DataSet("INFORMATION_SCHEMA.TABLE_CONSTRAINTS");

        //Create the dataadapter object
        SqlDataAdapter sDataAdapter = 
            new SqlDataAdapter(selectPrimaryKeys, sConnection);

        //Provides the master mapping between the sourcr table 
        //and system.data.datatable
        sDataAdapter.TableMappings.Add("Table", 
            "INFORMATION_SCHEMA.TABLE_CONSTRAINTS");

        //Fill the dataset
        sDataAdapter.Fill(dsListOfPrimaryKeys);

        //Bind the result combobox with primary key tables
        DataViewManager dvmListOfPrimaryKeys = 
            dsListOfPrimaryKeys.DefaultViewManager;
        dgResultView.DataSource = dsListOfPrimaryKeys
            .Tables["INFORMATION_SCHEMA.TABLE_CONSTRAINTS"];
    }
    catch(Exception ex)
    {
        //All the exceptions are handled and written in the EventLog.
        EventLog log = new EventLog("Application");
        log.Source = "MFDBAnalyser";
        log.WriteEntry(ex.Message);
    }
    finally
    {
        //If connection is not closed then close the connection
        if(sConnection.State != ConnectionState.Closed)
        {
            sConnection.Dispose();
        }
    }
}

Can anyone help me in removing these hardcoded things and taking the local server address, userid and password from the app.config file directly???

Answer 1

Sure.

first, open up your app.config or web.config file.

Look for the following section

<appSettings>
    <add key="...." value="....." />
    ....
</appSettings>

if that doesn’t exist, then it should be added.

Now add the following key/values…

<add key="myServer" value="192.168.10.3" />
<add key="myUserId" value="gp" />
<add key="myPassword" value="gp" />

and this is an example of what the app.config can now look like…

<?xml version="1.0" encoding="utf-8" ?>
<configuration>
   <appSettings>  
      <add key="myServer" value="192.168.10.3" />
      <add key="myUserId" value="gp" />
      <add key="myPassword" value="gp" />
   </appSettings>
</configuration> 

Kewl. Now lets update the code. The trick is to use the ConfigurationManager.AppSettings class :-

change…

sqlConnection.DataSource = "192.168.10.3";
sqlConnection.UserID = "gp";
sqlConnection.Password = "gp";

to..

sqlConnection.DataSource = ConfiguationManager.AppSettings["myServer"];
sqlConnection.UserID = ConfiguationManager.AppSettings["myUserId"];
sqlConnection.Password = ConfiguationManager.AppSettings["myPassword"];

Now you can change the values of those key/values (in the app.config or web.config) without having to compile the code 🙂

HTH