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 4 of 6

A heading and a doubled count

Level 4: Write it yourself · Exercise 1 of 2

Return id, characterName headed speaker, and the word count doubled, headed double_words, for the first four lines by id. Finish line: four rows, three columns, headings id, speaker and double_words.

Finish line: 4 rows · columns id, speaker, double_words · in the order the question gives

Data: Rick & Morty.

I would like help with this exercise

Table & column names only · ↑ ↓ choose · Tab insert · Esc dismiss

Open in the playground

Query results

Run your query to see the result here.

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