career page job crawler and content extraction

We require a web crawler/spider that specifically draws jobs and job descriptions out of a website. We can enter the main career URL (ie. [login to view URL])for the site directly into the database (MySQL), we then require the crawler to extract the jobs listed on that page and move to the individual job pages to extract the data and content from each individual job page (ie. [login to view URL]). The data then needs to be placed into the database after extraction. An issue to overcome is that many companies use dynamic URLs or changing parameters for their jobs.