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lab7_SelectQueries_Sowinski_Braeden.sql

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+-- Braeden Sowinski
+-- Set 2D
+
+SET search_path TO lab5;
+
+SELECT table_name
+FROM information_schema.tables
+WHERE table_schema = 'lab5';
+
+-- Quick peek per table
+SELECT * FROM student LIMIT 5;
+
+-- ### PART 1 - Basic SELECT ###
+
+-- Q1.1 List all students’ first and last names.
+SELECT stu_fname, stu_lname FROM student;
+
+-- Q1.2 List all courses (code + title).
+SELECT crs_code, crs_title FROM course;
+
+-- Q1.3 Show all lab offerings for for COMP 2714 in Fall 2025 (days + start time).
+SELECT off_days, off_start_time
+FROM course_offering
+WHERE off_crs_code = 'COMP 2714'
+AND off_term_code = '202550' -- Fall 2025
+AND off_type = 'Lab';
+
+-- Q1.4 Display all rows from your enrollment table.
+SELECT * FROM enrollment;
+
+-- ### PART 2 - INNER JOIN Practice ###
+
+-- Q2.1 List all students and the sections they are enrolled in. Include student name, section id, and term.
+SELECT student.stu_fname, course_offering.off_section, course_offering.off_term_code
+FROM student
+INNER JOIN enrollment
+ON student.stu_num = enrollment.stu_num
+INNER JOIN course_offering
+ON enrollment.off_id = course_offering.off_id;
+
+-- Q2.2 Show all course offerings with their course titles.
+SELECT course_offering.off_id, course_offering.off_section, course_offering.off_type, course.crs_title
+FROM course_offering
+INNER JOIN course
+ON course_offering.off_crs_code = course.crs_code;
+
+-- Q2.3 Display enrollments with the course title and the meeting days.
+SELECT enrollment.stu_num, enrollment.enr_status, course.crs_title, course_offering.off_days
+FROM enrollment
+INNER JOIN course_offering
+ON enrollment.off_id = course_offering.off_id
+INNER JOIN course
+ON course_offering.off_crs_code = course.crs_code;
+
+-- ### PART 3 - FILTERING & SORTING ###
+
+-- Q3.1 Students enrolled in Fall 2025 only (term code 202550).
+SELECT student.stu_fname, enrollment.enr_status, course_offering.off_term_code
+FROM student
+INNER JOIN enrollment
+ON student.stu_num = enrollment.stu_num
+INNER JOIN course_offering
+ON enrollment.off_id = course_offering.off_id
+WHERE off_term_code = '202550';
+
+-- Q3.2 Courses whose title contains the word Database (case-insensitive).
+SELECT *
+FROM course
+WHERE LOWER(crs_title) LIKE LOWER('%database%');
+-- No contains? LOWER() ensures that it doesnt matter if upper or lower case
+
+-- Q3.4 Students whose last name begins with C.
+SELECT *
+FROM student
+WHERE stu_lname LIKE 'C%';
+
+-- ### PART 4 - OUTER JOINs & NULLs
+
+-- Q4.1 All students with their enrollment info, including students with no enrollments (use LEFT JOIN).
+SELECT student.stu_fname, enrollment.*
+FROM student
+LEFT JOIN enrollment
+ON student.stu_num = enrollment.stu_num;
+
+-- Q4.2 Courses not offered in the current term.
+SELECT course.crs_title, course.crs_subject, course.crs_credits
+FROM course
+LEFT JOIN course_offering
+ON course_offering.off_crs_code = course.crs_code
+WHERE course_offering.off_term_code IS NULL;
+
+-- ### REFLECTION ###
+--
+-- Yes, all of the row counts make sense, there may
+-- be some duplicatoin. For example, when we are
+-- getting all student ids, and their enrollments,
+-- there may be duplicate enrollment data.
+-- i.e. two students are enrolled in the same
+-- course_offering. However, we since we are showing
+-- the student_id we are able to tell them apart.
+
+-- I dont think distinct would change the result
+-- in the example above, there is student x enrolled
+-- in class A, and student y enrolled in class A too.
+-- Those are already distinct.
+
+-- Yes I think I am selecting the minimul necessary
+-- columns, only showing relavent related information.