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.
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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- ADO.NET ODBC Connection
- ADO.NET Command
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- ADO.NET ExecuteNonQuery in OleDbCommand Object
- ADO.NET ExecuteScalar in SqlCommand Object
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- How to ADO.NET OleDbDataReader
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- Vb.NET ExecuteReader and ExecuteNonQuery