Useful resources for filter design

March 30, 2013

Some useful links I’ve found for designing passive RF filters:

Migrating from Lotus Approach to LibreOffice Base

March 10, 2013

I had a number of databases in Lotus Approach. Luckily, I’d had the foresight to make them dBASE databases, which LibreOffice knows a little about.

However, it doesn’t look as if LibreOffice knows much about Lotus Approach, which means all my existing forms were history. I started migrating them to LibreOffice forms. The form designer is a little rustic in LibreOffice (shift to multiselect on Windows, still can’t figure snap to grid out), but it’s enough to do what I need.

I used the automated form wizard to create forms from the fields first. That was enough to get started.

Next, I had a couple of fields that were combo boxes in Approach. To change the text field in LibreOffice Base to a combo box, I followed the instructions here:

In case that goes away, here’s the summary of what I did:

  1. Click on the text field that the wizard created
  2. Since that field is actually a group, pop up the context menu and say Group->Ungroup
  3. Click on the text field rather than the label
  4. Pop up the context menu and say Replace With->Combo Box
  5. Pop up the context menu and select “Control…” to open control properties
  6. All my combo boxes were populated from the database. To do that, choose the Data tab
  7. Change “Type of list contents” from “Table” to “Sql”
  8. For “List content”, enter SELECT DISTINCT “field” FROM “table” (e.g., SELECT “ARTIST” FROM “CD” for my CD database)
  9. Close the Properties dialog
  10. Re-group the field with its label

The same thing worked for dropdown lists – Replace With->List Box, change “Type of list contents” from “Valuelist” to “Sql” and use similar SQL to generate the list. I used “SELECT DISTINCT” rather than just “SELECT” because I didn’t want multiple copies showing up in my list box.