PgSqlDataReader Class

In This Topic

Reads a forward-only stream of rows from PostgreSQL.

Syntax

Visual Basic
C#

'Declaration
 
Public Class PgSqlDataReader 
   Inherits Devart.Common.DbDataReaderBase
   Implements System.Collections.IEnumerable, System.Data.IDataReader, System.Data.IDataRecord, System.IDisposable

public class PgSqlDataReader : Devart.Common.DbDataReaderBase, System.Collections.IEnumerable, System.Data.IDataReader, System.Data.IDataRecord, System.IDisposable

Remarks

To create a PgSqlDataReader, you must call the ExecuteReader method of the PgSqlCommand object, rather than directly using a constructor.

System.Data.Common.DbDataReader.IsClosed and Devart.Data.SqlShimDataReader.RecordsAffected are the only properties that you can call after the PgSqlDataReader is closed. In some cases, you must call Devart.Data.SqlShimDataReader.Close before you can call Devart.Data.SqlShimDataReader.RecordsAffected.

When protocol is ProtocolVersion.Ver20, the following restriction takes place. While the PgSqlDataReader is in use, the associated PgSqlConnection is busy serving the PgSqlDataReader, and no other operations can be performed on the PgSqlConnection other than closing it. This is the case until the Close method of the PgSqlDataReader is called. For example, you cannot retrieve output parameters until you call Close.

Example

The following example creates a PgSqlConnection, a PgSqlCommand, and a PgSqlDataReader. The example reads through the data, writing it out to the console. Finally, the example closes the PgSqlDataReader, then the PgSqlConnection.

csharp

public void ReadMyData(string myConnString)  {
        PgSqlConnection pgConnection = new PgSqlConnection(myConnString);
        PgSqlCommand pgCommand = (PgSqlCommand)pgConnection.CreateCommand();
        pgCommand.CommandText = "SELECT DeptNo, DName, Loc FROM Test.Dept";
        pgConnection.Open();
        PgSqlDataReader pgReader = pgCommand.ExecuteReader();
        try {
                // Always call Read before accessing data.
                while (pgReader.Read()) {
                Console.WriteLine(pgReader.GetInt32(0).ToString() + " " + 
                pgReader.GetString(1) + " " + pgReader.GetString(2));
        }
        }
        finally {
                // always call Close when done reading.
                pgReader.Close();

                // Close the connection when done with it.
                pgConnection.Close();
        }
}

Visual Basic

Public Sub ReadMyData(ByVal myConnString As String)
        Dim pgConnection As New PgSqlConnection(myConnString)
        Dim pgCommand As PgSqlCommand = pgConnection.CreateCommand()
                pgCommand.CommandText = "SELECT DeptNo, DName, Loc FROM Test.Dept"
        pgConnection.Open()
        Dim pgReader As PgSqlDataReader = pgCommand.ExecuteReader()
        Try
                ' Always call Read before accessing data.
                While pgReader.Read()
                        Console.WriteLine(String.Concat(pgReader.GetInt32(0).ToString(), " ", _
                        pgReader.GetString(1), " ", pgReader.GetString(2)))
                End While
        Finally
                ' always call Close when done reading.
                pgReader.Close()

                        ' Close the connection when done with it.
                        pgConnection.Close()
        End Try
End Sub

Inheritance Hierarchy

System.Object
   System.MarshalByRefObject
      System.Data.Common.DbDataReader
         Devart.Common.DbDataReaderBase
            Devart.Data.PostgreSql.PgSqlDataReader

Reference

PgSqlDataReader Members
Devart.Data.PostgreSql Namespace
PgSqlConnection Class
PgSqlCommand Class

Send Feedback