Databases & SQL
The actual language of relational data — queries, joins, and the practical skills behind working with SQL day to day, not just the system-design trade-offs.
16 lessons
Beginner
Tables, rows, and your first SELECT queryBeginner4 min read·Not startedINSERT, UPDATE, and DELETE — changing dataBeginner4 min read·Not startedJOINs — combining data across tablesBeginner4 min read·Not startedAggregation — COUNT, SUM, AVG, and GROUP BYBeginner4 min read·Not startedConstraints — letting the database enforce correctnessBeginner4 min read·Not startedNULL and three-valued logicBeginner4 min read·Not startedString and date functions, and CASE expressionsBeginner4 min read·Not started
Intermediate
Transactions and ACID, in practiceIntermediate4 min read·Not startedSubqueries — a query inside a queryIntermediate4 min read·Not startedCommon Table Expressions — naming a subqueryIntermediate4 min read·Not startedSet operations — UNION, INTERSECT, and EXCEPTIntermediate4 min read·Not startedNormalization — designing a schema that doesn't corrupt itselfIntermediate5 min read·Not startedViews — saving a query under a nameIntermediate4 min read·Not started