In this section, some useful SQL techniques are described. They are all used somewhere in the RBAC system, but most of them are generally applicable.
When joining tables in the ordinary way, it is better to use the explicit
INNER JOIN words between the tables, and to add
ON after the second table, followed by the conditions that define the join. This is clearer than using the comma notation and putting the join conditions in among the general
WHERE conditions. It will also work in a wider variety of database systems, and therefore has portability benefits.
One commonly used device applies to situations where a SQL
SELECT is built dynamically and may have differing numbers of
WHERE conditions according to circumstances. ...