ExecutePageReader Method (OracleCommand)

In This Topic

Syntax
Remarks
Example
See Also

Returns a specific subset of rows when paging through the results of a query.

Syntax

Visual Basic
C#

public new OracleDataReader ExecutePageReader( 
   CommandBehavior behavior,
   int startRecord,
   int maxRecords
)

'Declaration
 
Public Shadows Function ExecutePageReader( _
   ByVal behavior As CommandBehavior, _
   ByVal startRecord As Integer, _
   ByVal maxRecords As Integer _
) As OracleDataReader

Parameters

behavior: One of the System.Data.CommandBehavior values.
startRecord: Specifies the number of starting record of the set of records to be returned.
maxRecords: Specifies total number of records to retrieve.

Return Value

A OracleDataReader object with requested records.

Remarks

Use method ExecutePageReader when you want to retrieve not the whole dataset but some part of it that begins with given row number and has certain quantity of rows. This is especially useful when working with large amounts of data.

If you want to retrieve all data in a dataset, use ExecuteReader() instead.

Note: This method is not supported in .NET Standard 1.3 compatible assembly. It is available only in the assembly for full .NET Framework and .NET Standard 2.0 compatible assembly.

ExecutePageReader method puts on following restrictions on the executable statement:

- you cannot execute stored procedures and PL/SQL blocks;

- you may specify only SQL statement that can be placed into the subquery.

To use ExecutePageReader method it is recommended to optimize a query for retrieving a first row, otherwise using this method is ineffective.

Example

The example below shows how to retrieve a part of a table. If this function is called with parameters startRecord=2 and maxRecords=3, it returns 3 rows: second, third, and fourth.

csharp

public void ExecutePaged(OracleConnection myConnection, int StartRow, int PageLength)
{
  OracleCommand myCommand = new OracleCommand("SELECT * FROM Test.Dept", myConnection);
  myConnection.Open();
  OracleDataReader myReader = myCommand.ExecutePageReader(System.Data.CommandBehavior.Default,StartRow,PageLength);
  try
  {
    while (myReader.Read())
    {
      Console.WriteLine(myReader.GetInt32(0) + ", " + myReader.GetString(1) + ", " + myReader.GetString(2));
    }
  }
  finally
  {
    myReader.Close();
    myConnection.Close();
  }
}

Visual Basic

Public Sub ExecutePaged(ByVal myConnection As OracleConnection, ByVal StartRow As Integer, ByVal PageLength As Integer)
  Dim myCommand As New OracleCommand("SELECT * FROM Test.Dept", myConnection)
  myConnection.Open()
  Dim myReader As OracleDataReader = myCommand.ExecutePageReader(System.Data.CommandBehavior.Default, StartRow, PageLength)
  Try
    While myReader.Read()
      Console.WriteLine(myReader.GetInt32(0).ToString() + ", " _
      + myReader.GetString(1) + ", " _
      + myReader.GetString(2))
    End While
  Finally
    myReader.Close()
    myConnection.Close()
  End Try
End Sub

Reference

OracleCommand Class
OracleCommand Members
ExecuteReader() Method

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