Can I search a DataReader? (RESOLVED)

[AlvaroF1]

Based on the code:

Dim myConnection As New OleDb.OleDbConnection("Provider=Microsoft.Jet.OLEDB.4.0;Data Source=myDatabase.mdb")
Dim myCommand As New OleDb.OleDbCommand("SELECT * FROM myTable WHERE Name='Alvaro'")
Dim myDataReader As OleDb.OleDbDataReader
myConnection.Open()
myDataReader = myCommand.ExecuteReader

Is there a way to search the records stored in myDataReader?
Like:

myDataReader.Select("LastName='F1'")
If myDataReader.NoMatch Then
    MsgBox("Found.")
Else
    MsgBox("Not found.")
End If

Thanks.

[Pirate]

I did it different way . It may looks weird but for me , it get the job well done .

Public Shared Sub FineThis(ByVal MyTable As String, ByVal MyColumn As String, ByVal SearchWord As String)
        Dim MyPath As String = Application.StartupPath & "\anyfile.mdb"
        Dim MyConnection As New OleDb.OleDbConnection("Provider=Microsoft.Jet.OLEDB.4.0;Data Source=" & MyPath)
 
        Dim dr As OleDb.OleDbDataReader
Dim SQLString As String = "SELECT " & MyColumn & " FROM " & MyTable & " WHERE " & MyColumn & "='" & SearchWord & "'"
        Dim cmd As New OleDb.OleDbCommand(SQLString, MyConnection)
 
        MyConnection.Open()
        Try
            dr = cmd.ExecuteReader(CommandBehavior.CloseConnection)
            If dr.Read = True Then
                MessageBox.Show("Found :" & dr.Item(MyColumn))
            Else
                MessageBox.Show("No Matches")
            End If
        Catch ex As Exception
            MsgBox(ex.Message)
        End Try
        MyConnection.Close()
    End Sub

Usage :

FineThis("mytab", "c_url", TextBox1.Text)

[hellswraith]

I don't think you can with a datareader. You can do a loop until you find the value you are looking for.

Or
You can return a dataset, then do a dataview on it to search it.

Or
With your query, why don't you get more accurate results back.

SELECT * FROM myTable WHERE Name='Alvaro' AND LastName='F1'

If you get a result back, it is there (found). If not, then not found.

[Pirate]

And btw , DataReader obj , doesn't store values in it . It's just a fast and forward way to read a single data and gets back to its bed . .

hellswraith , did you test the code ?

[Pirate]

I know it's not the efficient way to do some search but at least this is what's he has been asking for .Check this demo :

[hellswraith]

I didn't test it, don't have time right now.

My thing is, why is he pulling data from the database that doesn't need to be pulled? Focusing your SQL Statement as much as possible to narrow the data returned is almost always the better bet.

If you need the extra data for something else, then the datareader shouldn't be used because it can only be looked at once. The dataset would be the better option.

[Pirate]

I've changed the SQL String to select only specified column .

Dim SQLString As String = "SELECT " & MyColumn & " FROM " & MyTable & " WHERE " & MyColumn & "='" & SearchWord & "'"

I agree , that dataset is best bet . This will be faster for some cases like :Checking username and password , checking if the entered data is already stored or not . This is how I use it usually .

[AlvaroF1]

Thank you all.

Here's my code solution:

Dim myConnection As New OleDb.OleDbConnection("Provider=Microsoft.Jet.OLEDB.4.0;Data Source=myDatabase.mdb")
Dim myAdapter As New OleDb.OleDbDataAdapter("SELECT * FROM myTable WHERE Name='Alvaro'", myConnection)
Dim myDataSet As New DataSet()
Dim myDataRow As DataRow()
myAdapter.Fill(myDataSet, "myTable")
myDataRow = myDataSet.Tables("myTable").Select("LastName='F1'")
If myDataRow.Length = 0 Then
    MsgBox("Not found.")
Else
    MsgBox("Found.")
End If