This method executes a command specified in the CommandText and returns an OracleDataReader object.

Declaration

// C#
public OracleDataReader ExecuteReader();

Return Value

An OracleDataReader.

Implements

IDbCommand

Exceptions

InvalidOperationException - The command cannot be executed.

Remarks

When the CommandType property is set to CommandType.StoredProcedure, the CommandText property should be set to the name of the stored procedure.

The specified command executes this stored procedure when ExecuteReader is called. If parameters for the stored procedure consist of REF CURSOR objects, behavior differs depending on whether ExecuteReader() or ExecuteNonQuery() is called. If ExecuteReader() is invoked, REF CURSOR objects can be accessed through the OracleDataReader that is returned.If more than one REF CURSOR is returned from a single execution, subsequent REF CURSOR objects can be accessed sequentially by the NextResult method on the OracleDataReader. If the ExecuteNonQuery method is invoked, the output parameter value can be cast to a OracleRefCursor type and the OracleRefCursor object then can be used to either populate a DataSet or create an OracleDataReader object from it. This approach provides random access to all the REF CURSOR objects returned as output parameters.

The value of 100 is used for the FetchSize. If 0 is specified, no rows are fetched. For further information, see "Obtaining LONG and LONG RAW Data".

If the value of the XmlCommandType property is set to OracleXmlCommandType.Insert, OracleXmlCommandType.Update, OracleXmlCommandType.Delete, or OracleXmlCommandType.Query then the ExecuteReader method throws an InvalidOperationException.

Example

// C#
 
using System;
using System.Data;
using Oracle.DataAccess.Client; 
 
class ExecuteReaderSample
{
  static void Main()
  {
    string constr = "User Id=scott;Password=tiger;Data Source=oracle";
    OracleConnection con = new OracleConnection(constr);
    con.Open();
 
    OracleCommand cmd = new OracleCommand("select ename from emp", con);

    OracleDataReader reader = cmd.ExecuteReader();

    while (reader.Read())
    {
      Console.WriteLine("Employee Name : " + reader.GetString(0));
    }
 
    // Clean up
    reader.Dispose();
    cmd.Dispose();
    con.Dispose();
  }
}