So i need to create A bunch of tables and i have some questions. WTF are constraints ? How they work ? and how would i fill a table like this ? Code: create table workers( A_T varchar(10),name varchar(30),birthdate date,phone double,street varchar(10),number integer, city varchar(10), primary key(A_T)); the numbers in parentheses limits the number of numbers letter in the key value? I dont really care about that since it works but it might cause problems later. TIA. If i do this before midnight ill have hope for the semester.