How to pass given week range condition to select query which is function module

Hi Experts,

I am Creating function Module in that i have to write a select query that query needs to retrieve fields from Custom table and the condition is based on date, between that dates i need to fetch. I have field as SUB_QUAN_TIMEST(char 14) and there is no start date and end date fields.

ie. i have to write like this where SUB_QUAN_TIMEST between given week range .

Can any one tell me how to write this .