17.3. Clean up ourBook sample data

00:00 after activating ourBook, there are also copied the sample data
00:05 to remove the data, go back to home workspace
00:07 because of data dependancy, housekeep the data of "book_Transaction" first
00:13 if deleting one record by one record, we need to sort out one side of the transaction pairs
00:17 so we use "Query" to sort out those with "Amount" less than 0
00:28 then select one or more records and "delete" them
00:51 then the other side of the transaction pairs will be deleted too
01:02 yet if it's sure all records are not needed, we may use "truncate" to remove all data inside a table
01:18 next we delete the records inside "book_Account"
01:26 we may delete all records if the sample records are all not needed
01:32 but some sample accounts may be useful for real situation
01:40 and so we may delete only some of the sample data
02:04 if it's sure all records are not needed, we may use "truncate" to remove all data inside a table
02:13 with "truncate" action, all data will be deleted without triggering "AutoAction", and the table structure can be preserved