1. A computer program product for managing query creation for querying a database with on demand database query reduction by selectively substituting, replacing, and removing specified variables within a sub-query before they are combined into an expanded query, said computer program product comprising: a computer readable medium; first program instructions responsive to a control document for executing a run-time agent in accordance with a first execution schedule to generate dynamic content by accessing control documents to find a control document ready for execution, with a control document including a user-adjustable second execution schedule controlling when final content is created, and, responsive to said second execution schedule, said run-time agent determining when to run a query document; said query document including global variables selectively bracketed by first tags identifying a first global variable as a complete replacement variable and by second tags identifying a second global variable as a complete removal string, a global variable being a variable which represents a quantity that is available to be modified by a user prior to runtime, said global variables being code definitions of a sub-query that are applied to form a master query and are manipulated by a substitution and replacement strategy to eventually form new content to a coded subquery, said run-time agent being a segment of code separate from said control document; second program instructions to build from said query document an expanded query by replacing any variables set off by said first tags with runtime strings, and setting off any unions in said query document; third program instructions selectively, for each set of second tags, for replacing variables in said string set off by said second tags, or removing said second tags without replacing variables set off by said second tags to restore said string set off by said second tags to normal syntax; and wherein said first, second, and third program instructions are recorded on said medium.