hi forum user :-)

i want to implement an undo/redo system for an application. The data for this application i will get from my MySQL database. The data are hierarchical data similar to filesystem-data. I implement it in the database with the nested set model.

So here is my question: Does anyone out there have an idea how i could use the database to make an undo/redo system. For example: When i delete an entry (or a complete subtree) i want to 'undo' this action (if posible unlimited undo's).

i would be grateful for any idea from you :-)

Willi

Hello Willi

I solved this with the help of history tables.

I created functions for update and delete, which backup the
original value with a modifier reason comment into the history table and
then execute the udpate or delete.

So you have the complete history of changes from all your data.

Example:

data(data_id, data_text)
history(hist_id, reason, timestamp)
data_hist(hist_id, data_id, data_text)

Walter