A lot of programmers are not fans of using exceptions to control the flow of the program. Most of your functions are using exceptions to exit out which is generally bad practice. Throw an exception when your program can not function.

For example, your secure function should be returning a true/false. It should also be a private function. Call the function in your exeQuery() method which would tell the exeQuery() method to finish execution. If it returns false the exeQuery() dosnt even execute the SQL query, and returns an empty dataset.