C# ADO.NET OleDbCommand - ExecuteScalar
The ExecuteScalar() in C# OleDbCommand Object uses to retrieve a single value from the Database after the execution of SQL Statements or Stored Procedures.
The ExecuteScalar() executes SQL statements or Stored Procedure and returned a scalar value on first column of first row in the returned Result Set. If the Result Set contains more than one columns or rows , it will return only the first column of the first row value and ignore all other values . If the Result Set is empty it will return a NULL reference.
Int32 count = Convert.ToInt32(cmd.ExecuteScalar());
It is very useful to use with aggregate functions like Count(*) or Sum() etc and also when compare to ExecuteReader() , ExecuteScalar() uses fewer System resources.
using System;
using System.Windows.Forms;
using System.Data.OleDb;
namespace WindowsApplication1
{
public partial class Form1 : Form
{
public Form1()
{
InitializeComponent();
}
private void button1_Click(object sender, EventArgs e)
{
string connetionString = null;
OleDbConnection cnn ;
OleDbCommand cmd ;
string sql = null;
connetionString = "Provider=Microsoft.Jet.OLEDB.4.0;Data Source=Your mdb filename;";
sql = "Your SQL Statement Here like Select Count(*) from product";
cnn = new OleDbConnection(connetionString);
try
{
cnn.Open();
cmd = new OleDbCommand(sql, cnn);
Int32 count = Convert.ToInt32(cmd.ExecuteScalar());
cmd.Dispose();
cnn.Close();
MessageBox.Show (" No of Rows " + count);
}
catch (Exception ex)
{
MessageBox.Show("Can not open connection ! ");
}
}
}
} |
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