Practise · Meet the table · Learn with Abdou

Opening your saved work…

The reading

One row is one spoken line

Open the playground, choose Rick & Morty, and run the five-row preview below. The first row is id 1: Rick, in the episode Pilot, saying 'Morty! You gotta come on. Jus'... you gotta come with me.' Nine columns describe that one line: which season and episode it belongs to, who said it, the words themselves, and how long it is. wordCount says 11. Count the words yourself; the table is right.

SELECT *
FROM scripts
ORDER BY id
LIMIT 5;

Five lines of the Pilot, every column. One row is one spoken line. Open in the playground

That is one row. Before you write any other query, finish this sentence for the table in front of you: one row in scripts represents one spoken line. Not one character: Rick is on 420 rows. Not one episode: Pilot is on 241. A familiar name is not an identifier. The id is, and it is the column you keep while you investigate, because it lets you point at one line and say this one.

SELECT names the columns you want, in the order you want them; FROM names the table. Asking for two columns instead of nine changes the shape of the result, not the number of rows: 1,905 lines stay 1,905 lines. ORDER BY id makes the first four mean the same four every time you run it, and LIMIT 4 keeps the preview short. A preview is a sample. It tells you what the table looks like; it cannot tell you anything about the lines you did not look at.

SELECT id, characterName, episodeName
FROM scripts
ORDER BY id
LIMIT 4;

Four rows, three columns. The same 1,905 lines are still in the table. Open in the playground

So make the claim as narrow as the evidence. Six rows that show only Rick and Morty are six lines and two names. They are not six characters, and they are not the main characters. Say what you saw, and keep the id so a teammate can look at the same six lines.

Rule of thumb. Say what one row is before you count, rank or claim anything.

Going deeper (optional, not on the exam)

The column names in scripts run words together, characterName and wordCount, because the file arrived that way. Northshore Coffee writes first_name and hourly_wage with underscores. Neither style is wrong; the schema panel tells you the exact spelling, and the exact spelling is the one the engine accepts.

SELECT * is for a first look. When you hand a result to someone who asked for three columns, name the three. The result is easier to read, and it does not change shape when a column is added to the table next year.

Meet the table · SELECT, FROM, ORDER BY id and LIMIT as a preview · level 3 of 6

Fewer columns, fewer rows?

Level 3: Predict the result · Exercise 2 of 2

SELECT * FROM scripts returns 1,905 rows and nine columns. This query asks for two of the nine columns and nothing else. Before you run it, how many rows come back?

SELECT characterName, episodeName
FROM scripts;

The query. Predict before you run it.

Data: Rick & Morty.

I would like help with this exercise

Opens once your prediction is right, or after the worked answer.

Query results

The real result appears here after you run it.

Practice here is evidence for you and your instructor, never a grade. Grades live in Canvas.