Consider the following relational database that Best Airlines uses to keep track of its mechanics, their skills, and their airport locations. Mechanic number (MECHNUM), airport name (AIRNAME), and skill number are all unique fields. SIZE is an airport’s size in acres. SKILLCAT is a skill category, such as an engine skill, wing skill, tire skill, etc. YEARQUAL is the year that a mechanic first qualified in a particular skill; PROFRATE is the mechanic’s proficiency rating in a particular skill.

MECHANIC Table
MECHNUM	MECHNAME	AGE	SALARY	AIRNAME

AIRPORT Table
AIRNAME	CITY	STATE	SIZE	YEAROPENED

SKILL Table
SKILLNUM	SKILLNAME	SKILLCAT

QUALIFICATION Table
MECHNUM	SKILLNUM	YEARQUAL	PROFRATE

Write SQL SELECT commands to answer the following queries.

• a. List the names and ages of all the mechanics.
• b. List the airports in California that are at least 20 acres in size and have been open since 1935. Order the results from smallest to largest airport.
• c. List the airports in California that are at least 20 acres in size or have been open since 1935.
• d. Find the average size of the airports in California that have been open since 1935.
• e. How many airports have been open in California since 1935?
• f. How many airports have been open in each state since 1935?
• g. How many airports have been open in each state since 1935? Include in your answer only those states that have at least five such airports.
• h. List the names of the mechanics who work in California.
• i. Fan blade replacement is the name of a skill. List the names of the mechanics who have a proficiency rating of 4 in fan blade replacement.
• j. Fan blade replacement is the name of a skill. List the names of the mechanics who work in California who have a proficiency rating of 4 in fan blade replacement.
• k. List the total, combined salaries of all of the mechanics who work in each city in California.
• l. Find the largest of all of the airports.
• m. Find the largest airport in California.