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SQL: Select and Filter

Lesson 2/3

WHERE passes the rows through a condition: those that meet it stay, the others go. The condition is asked of each row on its own; think of Python's if, run separately for every row.

SELECT title, price
FROM books
WHERE price < 100
  AND (genre = 'poetry' OR genre = 'essay');
Equality is written with a single = (not Python's ==), and texts go in single quotes. AND wants both conditions, OR either. This query brings the poetry and essay books that cost less than 100.

When you compare the same column with several values, IN reads better: genre IN ('poetry', 'essay'). For a range you write BETWEEN 50 AND 100, which includes both ends.

Tasks

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  1. 01

    Filter

    SQL query

  2. 02

    Several conditions

    SQL query

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