This week's book giveaway is in the OO, Patterns, UML and Refactoring forum. We're giving away four copies of Refactoring for Software Design Smells: Managing Technical Debt and have Girish Suryanarayana, Ganesh Samarthyam & Tushar Sharma on-line! See this thread for details.
As long as i can remembered, the limit syntaxes differ from 1 vendor to another, ex mysql uses keyword limit, oracle uses the rownum function, etc.
It's almost impossible to use standard ways in persistence layer. Perhaps you should code different classes for different database/any other legacy systems, and plug the correct ones to the business process tier. Data Access Object, Inversion of Control/Abstract Factory and Factory pattern could do some help.