Update instead insert

i save data for different model because i have a two type of user , the first part (a simple registration data) i save into a table users , the second part is specific of the type of user and i save it in the specific table

I asked because I wanted to be sure if you have the same columns in your second table?

Btw, did you set auto increment for ID in your db table?

I have id in user autoincrement , in dentisti i have id_user (foreign key of user ) without id