How to Parse Query string and store in SQL table?

Hi,
I have a requirement to allow administrator to add query string, save it in the database and use it as part of Where Clause in SQL query.
I am building this site for a school which has got different modules.
For example - When a student applys to do Module "C", the system should check whether the student has already done Module A and Module B (in order to do Module C, student should pass module A and B; but this can change any time.)
This prerequisite is decided by the course administrator and it can change any time.
The prerequisites can have many and or or clauses and also there can be dates checking as well eg. when the student passed the prerequisite course.
So, I am planning give a text box where administrator can enter prerequisites like "prerequiresitecourse=Module A and passeddate='1/1/2014' and prerequiresitecourse=Module B passeddate='1/5/2014'". T ...