Show me the steps to solve these SQL queries. Here are the tables :

student $($sid$,$ sname, sex, age, year, gpa$)$ dept $($dname$,$ numphds$)$

prof $($pname$,$ dname$)$

course $($cno$,$ cname, dname$)$

major $($dname$,$ sid$)$

section $($dname$,$ cno, sectno$,$ pname$)$ enroll $($sid$,$ grade, dname, cno, sectno$).$

The queries I need to answer are as follows :

$1.$ Print the names of professors who work in departments that have fewer than $50$ PhD students

$2.$ Print the names of the students with the lowest GPA

$3.$ For each Computer Sciences class, print the class number, section number, and the average gpa of the students enrolled in the class section

$4.$ Print the names and section numbers of all sections with more than six students enrolled in them

$5.$ List the department names and the number of classes offered in each department.

$6.$ Print the names of departments that have one or more majors who are under $18$ years old

$7.$ Print the names and majors of students who are taking one of the College Geometry courses

$8.$ For those departments that have no major taking a College Geometry course print the department name and the number of PhD students in the department

$9.$ Print the names of students who are taking either a Computer Sciences course or a Mathematics course

$10.$ Print the age difference between the oldest and the youngest Computer Sciences major

$11.$ For each department that has one or more majors with a GPA under $1\mathrm{.}0,$ print the name of the department and the average GPA of its majors

$12.$ Print the ids, names and GPAs of the students who are currently taking all the Civil Engineering courses