Adobe Acrobat URL Decoding

I am new at Adobe Acrobat and LiveCycle. Using Acrobat 7.0.8, LiveCycle 6.0. I am able to connect a form to a database,but need to filter to a certain record OnOpen.. What I need is instructions, sample code, (Manual if you will) to be able to pass data to the Acrobat form either by URL or Post method. Parse or decode the passed data and fill textbox etc. The value in a textbox would then be used in a SQL Query and or SP... Need instructions on how to construct the "WHERE" part of the SQL Query. NOT how to construct a query, but just the where part. In short, I need a detailed how to, step by step guide to accomplish this action.