Build dynamic registratiion

I need to build a dynamic registration fileld and this field will be contolled by the admin.Basically I am not going to hard code the fields in the html form

My db is as follows


reg_form_text: (This filed will be text box,drop down,text-area etc)
reg_form_text_type: (input,check-box,radio button etc)
reg_page_position: ( order in the page such as 1,2,3,4,5,6 etc)
reg_page_status: ( enabled/disabled for the page.Admin will decide wether to show the field in the page)

Based on this I can display in the page.

But I have no idea how to store values in the database when a user submit the registration page.

Can anyone help me to solve