DatabaseSlot.cs

public class DatabaseSlotsExample : IPrefetchable
{
  protected List<string> values = new List<string>(); // store your values here
  
  public static List<string> Values
  {
    get
    {
      //Get the values from the slot dynamically. By providing table name, you inform system when it should reset the slot.
      return PXDatabase.GetSlot<DatabaseSlotsExample>("SlotSuperKey", typeof(YourTable)).values;
    }
  }

  public void Prefetch()
  {
    //read database here
    foreach(PXDataRecord rec in PXDatabase.SelectMulti<YourTable>(
        new PXDataField<YourTable.tableField>(), //definition for fields that system should select
        new PXDataFieldValue<YourTable.tableKey>("Some Condition") //definition for restriction that you need to apply
      ))
    {
      //populate your collection from the database here
      values.Add(rec.GetString(0));
    }
  }
}