This method executes the query using the connection, and returns the first column of the first row in the result set returned by the query.

Declaration

// C#
public override object ExecuteScalar();

Return Value

An object which represents the value of the first row, first column.

Implements

IDbCommand

Exceptions

InvalidOperationException - The command cannot be executed.

Remarks

Extra columns or rows are ignored. ExecuteScalar retrieves a single value (for example, an aggregate value) from a database. This requires less code than using the ExecuteReader() method, and then performing the operations necessary to generate the single value using the data returned by an OracleDataReader.

If the query does not return any row, it returns null.

The ExecuteScalar method throws an InvalidOperationException, if the value of the XmlCommandType property is set to one of the following OracleXmlCommandType values: Insert, Update, Delete, Query.

Example

// C#
 
using System;
using System.Data;
using Oracle.DataAccess.Client; 
 
class ExecuteScalarSample
{
  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 count(*) from emp", con);
 
    object count = cmd.ExecuteScalar();
 
    Console.WriteLine("There are {0} rows in table emp", count);
 
    // Clean up
    cmd.Dispose();
    con.Dispose();
  }
}