projecting the literal 'hi' for table dept 'H -- hi hi hi hi hi dept_num concatenated with dept_name: DEPT_NUM||DEPT_NAM ------------------ 100Accounting 200Research 300Sales 400Operations 500Management what if I concatenate a literal ' - ' between dept_num and dept_name? DEPT_NUM||'-'||DEPT_N --------------------- 100 - Accounting 200 - Research 300 - Sales 400 - Operations 500 - Management how about adding a column alias: Departments --------------------- 100 - Accounting 200 - Research 300 - Sales 400 - Operations 500 - Management projecting department data in comma-separated/CSV format: DEPT_NUM||','||DEPT_NAME||','||DEPT_L ------------------------------------- 100, Accounting, New York 200, Research, Dallas 300, Sales, Chicago 400, Operations, Boston 500, Management, New York names of departments located in Chicago or Dallas: DEPT_NAME --------------- Research Sales adding a Computer Sci row to dept 1 row created. which departments currently have employees? (for each department, do any employees EXIST for that department?) DEPT_LOC DEPT_NAME --------------- --------------- New York Accounting Dallas Research Chicago Sales Boston Operations New York Management which departments have NO employees? DEPT_LOC DEPT_NAME --------------- --------------- Arcata Computer Sci OOOPS I left off the correlation condition with NOT EXISTS! (you might think it means all departments have employees, but Computer Sci department does not) (this will show no rows selected, even though Computer dept has no employees...) no rows selected OOPS, left off correlation condition with EXISTS! (you might think it means all departments have employees, but Computer Sci department does not) (this will also select Computer Sci dept, even though Computer Sci dept has no employees...) DEPT_LOC DEPT_NAME --------------- --------------- New York Accounting Dallas Research Chicago Sales Boston Operations New York Management Arcata Computer Sci 6 rows selected. OOOPS I turned my correlation condition INTO a join condition! (this will show no rows selected, even though Computer dept has no employees...) no rows selected using the HW 4 database, which client(s) have rented BOTH 'Gone with the Wind' and 'Star Wars'? Starry Wind client(s) -------------------------------- Beta, Edie has Edie Beta really rented both? MOVIE_TITLE ---------------------------------------- Star Wars Gone with the Wind Indiana Jones and the Temple of Doom