dbdata.CommandText = "SELECT * FROM Tabelle"
reader = dbdata.ExecuteReader
 
while reader.read
    t1.text = reader.item("Feld")
 
    if t1.text = "Hallo" then
            dbdata2.commandtext="UPDATE Tabelle SET Fled='Tag'"
            dbdata2.executenonquery
    end if
end while
reader.close