Connect to Oracle using ASP.Net and C# or VB.Net

By | January 6, 2009
  • Create a new project in Visual Studio using eight C# or VB.Net
  • Add reference to Oracle.DataAccess.dll file. Typically this file can be found in C:\oracle\product\10.2.0\client_1\BIN directory. This directory may be different based on your oracle configuration.
  • Once library is referenced, go to your class file where you want to create oracle connection.
  • Add following statements based on language you selected for project.

{codecitation class=”brush:vbnet;”}

Imports Oracle.DataAccess.Client ‘ VB.NET

{codecitation class=”brush:c-sharp;”}

using Oracle.DataAccess.Client; // C#


  • An Oracle connection string is inseparable from Oracle names resolution. Suppose we had a database alias of OraDb defined in a tnsnames.ora file as follows:


  • The OraDb alias defines the database address connection information for the client. To use the OraDb alias defined in the tnsnames.ora file shown above, you would use the following syntax:

{codecitation class=”brush:vbnet;”}

Dim oradb As String = “Data Source=OraDb;User Id=scott;Password=tiger;” ‘ VB.NET

string oradb = “Data Source=OraDb;User Id=scott;Password=tiger;”; // C#


  • You can modify the connection string to obviate the need for the tnsnames.ora file, however. Simply replace the name of the alias with how it would be defined in a tnsnames.ora file.

    {codecitation class=”brush:vbnet;”}

    ‘ VB.NET

Dim oradb As String = “Data Source=(DESCRIPTION=” _
+ “User Id=scott;Password=tiger;”

// C#
string oradb = “Data Source=(DESCRIPTION=”
+ “User Id=scott;Password=tiger;”;


  • Now you can create connection object from the connection string above. The connection string must be associated with the connection object.

{codecitation class=”brush:vbnet;”}

Dim conn As New OracleConnection(oradb) ‘ VB.NET

OracleConnection conn = new OracleConnection(oradb); // C#


  • Now you can use this connection like any other connection and do various database tasks.
  • To open a connection, use following statements,

{codecitation class=”brush:vbnet;”}

conn.Open() ‘ VB.NET

conn.Open(); // C#


  • To create a command object, use following statements,

{codecitation class=”brush:vbnet;”}

Dim sql As String = “select dname from dept where deptno = 10” ‘ VB.NET
Dim cmd As New OracleCommand(sql, conn)
cmd.CommandType = CommandType.Text

string sql = “select dname from dept where deptno = 10”; // C#
OracleCommand cmd = new OracleCommand(sql, conn);
cmd.CommandType = CommandType.Text;


  • You can retrieve values from command object using following statement,

{codecitation class=”brush:vbnet;”}

Dim dr As OracleDataReader = cmd.ExecuteReader() ‘ Visual Basic

Label1.Text = dr.Item(“dname”) ‘ retrieve by column name
Label1.Text = dr.Item(0) ‘ retrieve the first column in the select list
Label1.Text = dr.GetString(0) ‘ return a .NET data type
Label1.Text = dr.GetOracleString(0) ‘ return an Oracle data type
OracleDataReader dr = cmd.ExecuteReader(); // C#

label1.Text = dr[“dname”].ToString(); // C# retrieve by column name
label1.Text = dr.GetString(0).ToString(); // return a .NET data type
label1.Text = dr.GetOracleString(0).ToString(); // return an Oracle data type


  • All open connection objects should be closed once you are done using them.

{codecitation class=”brush:vbnet;”} conn.Close() ‘ Visual Basic
conn.Dispose() ‘ Visual Basic

conn.Close(); // C#
conn.Dispose(); // C# {/codecitation}


Category: C#

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