Introduction to SQL

Lessons

Work through the fundamentals, one concept at a time.

  1. 1What is SQL?Beginner5 minSQL is the language for asking questions of relational databases. Learn what it is, why every major database speaks a dialect of it, and how it differs from NoSQL.
  2. 2SELECT: choosing columns and rowsBeginner8 minRetrieve exactly the columns and rows you need with SELECT and WHERE, and see how the same filter is expressed in MongoDB.
  3. 3Limiting results: the biggest dialect splitIntermediate7 minReturning just the top N rows is where SQL dialects diverge the most. Compare LIMIT, TOP and FETCH FIRST across every database, plus MongoDB's limit().