Practise · Name the result · Learn with Abdou

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The reading

Name the result

The recap editor does not want a heading called characterName. Write characterName AS speaker and the output column is called speaker. That is all an alias does: it names a column of this result, for this query. Open the schema panel and the table still says characterName. Nothing was renamed.

An expression calculates a column that was never stored. wordCount + 5 AS five_more_words gives 16 for id 1, whose wordCount is 11. Run SELECT wordCount FROM scripts WHERE id = 1 afterwards and you get 11 again. SELECT reads; it never writes. Check an expression against one row you can do in your head, 11 plus 5, before you trust it on 1,905.

SELECT id, characterName AS speaker, wordCount + 5 AS five_more_words
FROM scripts
ORDER BY id
LIMIT 3;

Three rows: 11 becomes 16, 5 becomes 10, 7 becomes 12. The stored word counts stay 11, 5 and 7. Open in the playground

Text joins with ||, not with +. characterName || ' in ' || episodeName AS scene_label gives Rick in Pilot. The single quotes around ' in ' make it a piece of text, spaces included. Leave the quotes off a column name; put them on anything that is literally text.

SELECT characterName || ' in ' || episodeName AS scene_label
FROM scripts
ORDER BY id
LIMIT 5;

One column. The first label is Rick in Pilot, with the spaces the quotes asked for. Open in the playground

Now put quotes where they do not belong: SELECT 'characterName' AS speaker. The engine does not complain. It prints the word characterName on every row, because quoted text is a value, not a column. It ran. That is not the same as being right. When a column repeats one word all the way down, look for quotes that should not be there.

Rule of thumb. An alias names the output and an expression calculates it; neither changes what is stored.

Going deeper (optional, not on the exam)

The browser engine divides two whole numbers as whole numbers: 5 / 2 gives 2, not 2.5. Write 5 / 2.0 when you want the fraction, and runtime / 60.0 when you turn minutes into hours. Chapter 4 comes back to this.

+ adds numbers. Write characterName + episodeName and the engine tries to add two pieces of text and answers 0 rather than complaining. The text operator is ||.

An alias with a space in it needs double quotes: phone AS "Front Desk". Single quotes are for text values. You can sort by an alias, ORDER BY five_more_words, but inside WHERE repeat the expression itself.

Name the result · aliases, expressions and text labels · level 3 of 6

Did the word count change?

Level 3: Predict the result · Exercise 1 of 1

You ran SELECT id, wordCount + 5 AS five_more_words FROM scripts ORDER BY id LIMIT 8 and saw 16 for id 1. Now you run the query below. Before you run it, what value comes back?

SELECT wordCount
FROM scripts
WHERE id = 1;

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.