Unit 7 · Data that lasts
SQL clause order: SELECT, FROM, WHERE, ORDER BY
SQL clauses go in a fixed order: SELECT the columns, FROM a table, WHERE to filter rows, then ORDER BY to sort. Put them in another order and the query fails.
The mix-up
What people often think
“The parts of a query can go in any order.”
What the tutor says
SQL has a fixed order: SELECT, then FROM, then WHERE, then ORDER BY. Move the WHERE before the ORDER BY.
How it works
Without ORDER BY, the database promises no order at all. Rows might come back newest first today and in a different order tomorrow, so ask for the order you need.
Side by side
SELECT name FROM customers ORDER BY name WHERE city = 'Toronto';SELECT name FROM customers
WHERE city = 'Toronto'
ORDER BY name;Close cousins of this mix-up
The tutor watches for these in the same lesson.
“Rows come back newest first on their own.”
Without ORDER BY, the order is not promised. Add ORDER BY created_at DESC.
Practise it with a tutor watching
Tables and rows
Read a database table and write SELECT, INSERT and a safe UPDATE in SQL.
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