Week 9: Outer Joins and Set Operations

Due: Wednesday, Oct 21st

Thursday's class covers outer joins and set operations, and HW5 leans on both. Outer joins are where careful readers and careless readers separate, because the query runs either way and only one version is correct.

Prompt

Paste the standard prompt, then paste this block.

Topic: Outer joins and set operations.

My learning objectives:
- Predict the output of a LEFT, RIGHT, or FULL outer join,
  including which rows appear and which columns are NULL.
- Explain what a NULL in an outer join result actually means.
- Choose correctly among UNION, INTERSECT, and EXCEPT.

Quiz me on these objectives. Give me one short problem at a
time and wait for my answer, and don't explain anything unless
I get it wrong or ask you to.

Sources

• 1.4 Queries on multiple tables, specifically the outer join material. You read the first part of this section in Week 2.
• 1.10 Set operations

Ask for predictions, not answers

The most useful thing you can do this week is have the assistant show you two small tables and a join, and ask you what comes out before it tells you. If the assistant keeps answering its own questions, tell it to stop.