6.8 OracleDataReader Class
An OracleDataReader object represents a forward-only, read-only, in-memory result set.
Unlike the DataSet, the OracleDataReader object stays connected and fetches one row at a time.
The following section contain related information:
Class Inheritance
System.Object
System.MarshalByRefObject
System.Data.Common.DataReader
System.Data.Common.DbDataReader
Oracle.DataAccess.Client.OracleDataReader
Declaration
// C# public sealed class OracleDataReader : DbDataReader, IEnumerable, IDataReader, IDisposable, IDataRecord
Requirements
| Provider | ODP.NET, Unmanaged Driver | ODP.NET, Managed Driver |
|---|---|---|
|
Assembly |
|
|
|
Namespace |
|
|
|
.NET Framework |
3.5, 4.5, 4.6 |
4.5, 4.6 |
Thread Safety
All public static methods are thread-safe, although instance methods do not guarantee thread safety.
Remarks
An OracleDataReader instance is constructed by a call to the ExecuteReader method of the OracleCommand object. The only properties that can be accessed after the DataReader is closed or has been disposed, are IsClosed and RecordsAffected.
To minimize the number of open database cursors, OracleDataReader objects should be explicitly disposed.
Example
The following OracleDataReader example retrieves the data from the EMP table:
/* Database Setup, if you have not done so yet.
connect scott/tiger@oracle
CREATE TABLE empInfo (
empno NUMBER(4) PRIMARY KEY,
empName VARCHAR2(20) NOT NULL,
hiredate DATE,
salary NUMBER(7,2),
jobDescription Clob,
byteCodes BLOB
);
Insert into empInfo(EMPNO,EMPNAME,JOBDESCRIPTION,byteCodes) values
(1,'KING','SOFTWARE ENGR', '5657');
Insert into empInfo(EMPNO,EMPNAME,JOBDESCRIPTION,byteCodes) values
(2,'SCOTT','MANAGER', '5960');
commit;
*/
// C#
using System;
using System.Data;
using Oracle.DataAccess.Client;
class OracleDataReaderSample
{
static void Main()
{
string constr = "User Id=scott;Password=tiger;Data Source=oracle";
OracleConnection con = new OracleConnection(constr);
con.Open();
string cmdstr = "SELECT * FROM EMPINFO";
OracleConnection connection = new OracleConnection(constr);
OracleCommand cmd = new OracleCommand(cmdstr, con);
OracleDataReader reader = cmd.ExecuteReader();
// Declare the variables to retrieve the data in EmpInfo
short empNo;
string empName;
DateTime hireDate;
double salary;
string jobDesc;
byte[] byteCodes = new byte[10];
// Read the next row until end of row
while (reader.Read())
{
empNo = reader.GetInt16(0);
Console.WriteLine("Employee number: " + empNo);
empName = reader.GetString(1);
Console.WriteLine("Employee name: " + empName);
// The following columns can have NULL value, so it
// is important to call IsDBNull before getting the column data
if (!reader.IsDBNull(2))
{
hireDate = reader.GetDateTime(2);
Console.WriteLine("Hire date: " + hireDate);
}
if (!reader.IsDBNull(3))
{
salary = reader.GetDouble(3);
Console.WriteLine("Salary: " + salary);
}
if (!reader.IsDBNull(4))
{
jobDesc = reader.GetString(4);
Console.WriteLine("Job Description: " + jobDesc);
}
if (!reader.IsDBNull(5))
{
long len = reader.GetBytes(5, 0, byteCodes, 0, 10);
Console.Write("Byte codes: ");
for (int i = 0; i < len; i++)
Console.Write(byteCodes[i].ToString("x"));
Console.WriteLine();
}
Console.WriteLine();
}
// Clean up
reader.Dispose();
con.Dispose();
}
}