Retrieving Data Using a DataReader

The DataReader provides the fastest but least flexible way to retrieve data from the database. Data is returned as a read-only, forward-only stream of data that is returned one record at a time. If you need to retrieve many records rapidly, using a DataReader would require less memory than a DataSet, which would need to create a large table to hold the results.

The following code example, which requires the emp table (see Sample Tables for Pervasive.SQL ), shows how to execute a simple query on a Pervasive.SQL database and read the results using a DataReader:

// Open connection to Pervasive.SQL database 
PsqlConnection  Conn; 
Conn = new PsqlConnection("ServerDSN=DEMODATA; 
								UID=test; 
								PWD=test; 
                           Server=localhost"); 
Conn.Open(); 
// Create a SQL command 
string strSQL = "SELECT ename FROM emp WHERE sal>50000"; 
PsqlCommand   DBCmd = new PsqlCommand(strSQL, Conn); 
PsqlDataReader  myDataReader; 
myDataReader = DBCmd.ExecuteReader(); 
while (myDataReader.Read()) 
{ 
     Console.WriteLine("High salaries: " + 
myDataReader["ename"].ToString()); 
} 
myDataReader.Close(); 
//  Close the connection 
Conn.Close();