Access a SQL database

Access a SQL database by using the System.Data.SqlClient library.



// This example needs the
// System.Data.SqlClient library

#region Building the connection string

string Server = "localhost";
string Username = "my_username";
string Password = "my_password";
string Database = "my_database";

string ConnectionString = "Data Source=" + Server + ";";
ConnectionString += "User ID=" + Username + ";";
ConnectionString += "Password=" + Password + ";";
ConnectionString += "Initial Catalog=" + Database;

#endregion


#region Try to establish a connection to the database

SqlConnection SQLConnection = new SqlConnection();

try
{
SQLConnection.ConnectionString = ConnectionString;
SQLConnection.Open();

// You can get the server version
// SQLConnection.ServerVersion
}
catch (Exception Ex)
{
// Try to close the connection
if (SQLConnection != null)
SQLConnection.Dispose();

// Create a (useful) error message
string ErrorMessage = "A error occurred while trying to connect to the server.";
ErrorMessage += Environment.NewLine;
ErrorMessage += Environment.NewLine;
ErrorMessage += Ex.Message;

// Show error message (this = the parent Form object)
MessageBox.Show(this, ErrorMessage, "Connection error", MessageBoxButtons.OK, MessageBoxIcon.Error);

// Stop here
return;
}

#endregion


#region Execute a SQL query

string SQLStatement = "SELECT * FROM ExampleTable";

// Create a SqlDataAdapter to get the results as DataTable
SqlDataAdapter SQLDataAdapter = new SqlDataAdapter(SQLStatement, SQLConnection);

// Create a new DataTable
DataTable dtResult = new DataTable();

// Fill the DataTable with the result of the SQL statement
SQLDataAdapter.Fill(dtResult);

// Loop through all entries
foreach (DataRow drRow in dtResult.Rows)
{
// Show a message box with the content of
// the "Name" column
MessageBox.Show(drRow["Name"].ToString());
}

// We don't need the data adapter any more
SQLDataAdapter.Dispose();

#endregion


#region Close the database link

SQLConnection.Close();
SQLConnection.Dispose();

#endregion


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