SQL
From wikinotes
The SQL spec is standardized by ISO/ANSI and must be purchased.
It's difficult to validate these notes without it.
This attempts to document the more general SQL-ish features available across SQL databases.
Documentation
SQL spec (unofficial) https://jakewheat.github.io/sql-overview/
Challenges
https://quip.com/2gwZArKuWk7W
Notes
sql: datatypes sql: queries sql: mutations sql: comparison operators sql: joins sql: dates sql: aggregate functions sql: optimization