Skip to main content
PProfileMatch
Read Play
← Path

SQL Fundamentals · SQL SELECT, WHERE, ORDER BY and LIMIT: Querying Your First Table

0 XP
  1. 1 current stop: learning
  2. 2 upcoming
  3. 3 upcoming
  4. 4 upcoming
  5. 5 upcoming

Finish after stop 5

Stop 1 of 5 · Trailhead map board

Trick to keep in mind+3 XP

Few Wolves Sing Old Lullabies: FROM, WHERE, SELECT, ORDER BY, LIMIT.

You write SELECT first, but that is not the order the database works in. It first needs a table to look at, then throws away rows that fail the filter, and only then builds the output columns, sorts them and cuts the list. That is why a WHERE clause cannot use an aggregate or an alias that only exists once SELECT has run.

Read it once, then a question tests whether the trick stuck.