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Checking Out
To prevent more than one user trying to edit one record at a time we can check out
records (a form of software record locking). We use two fields to do this, checked_
out and checked_out_time. checked_out, of type integer, holds the ID of the
user that has checked out the record. checked_out_time, of type datetime, holds
the date and time when the record was checked out. A null date and a user ID of 0 is
recorded if the record is not checked out.
Ordering
We often want to allow administrators the ability to choose the order in which
items appear. The ordering field, of type integer, can be used to number records
sequentially to determine the order in which they are displayed. This field does
not need to be unique and can be used in conjunction with WHERE clauses to form
ordering groups.
Parameter Fields
We use a parameter field, a TEXT field normally named params, to store additional
information about records; this is often used to store data that determines how a
record will be displayed.


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