Q. Should I use TPSQLUpdateSQL everytime with TPSQLQuery?
A. No, it should be used only for the following queries types.
Queries with operators in the field list:
Queries with constants or function calls in the field list:
In other words, Query may be modified automatically (without using TPSQLUpdateSQL), if it consists of plain field list taken from one and only one table.
This, however, doesn't mean that you can not use other table or function references in FROM clause, e.g.