Lesson 9 of 11
The big picture
Show on a big screenEight ideas, one line each. Every count below came from a real run.
| Idea | Remember | Example |
|---|---|---|
| One record, one row | A row is four values kept together, found by two positions. | rows[2][3] → 1450 |
| The naming value | A key is a column whose values each name one record. | Ananya is shared; admission is not |
| Naming the columns | A header name becomes a position; minus one means absent. | indexOf('marks') → −1 |
| Asking one condition | A query walks every row and keeps the matches. | due 1450: 4 of 12 |
| Two conditions | A row must meet both conditions — fewer rows or the same. | 9-A and due ≥ 1000: 4 of 12 |
| The answer, in order | Same passes, moving whole rows. Two tied rows are never swapped with each other. | smallest due in the four rows: A-107 |
| Counting the groups | Count the answer, not the table. Groups listed first show a 0. | 9-A 4, 9-B 4, 10-C 0 |
| What a database adds | A database program can give the same answer as the walk, on much bigger tables. | 12 rows now, thousands later |
One point holds for all eight. Every number above came from a real run, never from memory.
Next term the questions turn to a program's guesses. Your next track is How AI Learns II: Neural Networks Intuition.