ADO.NET ExecuteScalar in OleDbCommand Object

ExecuteScalar() in OleDbCommand Object is used for get a single value from Database after its execution. It executes SQL statements or Stored Procedure and returned a scalar value on first column of first row in the Result Set. If the Result Set contains more than one columns or rows , it takes only the first column of first row, all other values will ignore. If the Result Set is empty it will return a Null reference. It is very useful to use with aggregate functions like Count(*) or Sum() etc. When compare to ExecuteReader() , ExecuteScalar() uses fewer System resources.

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Imports System.Data.OleDb
Public Class Form1
    Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click
        Dim connetionString As String
        Dim cnn As OleDbConnection
        Dim cmd As OleDbCommand
        Dim sql As String

        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)
            Dim count As Int32 = Convert.ToInt32(cmd.ExecuteScalar())
            cmd.Dispose()
            cnn.Close()
            MsgBox(" No of Rows " & count)
        Catch ex As Exception
            MsgBox("Can not open connection ! ")
        End Try
    End Sub
End Class

connetionString = "Provider = Microsoft.Jet.OLEDB.4.0; Data Source = Your mdb filename;"
sql = "Your SQL Statement Here like Select Count(*) from product"

You have to replace the string with your realtime variables.

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