Data Coding

Lesson 5.4 · Pro

Find rows with no match

Anti-joins (no match) and semi-joins (has a match), and the NOT IN trap with NULLs.

In this lesson

  1. LEFT JOIN, then keep the NULLs
  2. NOT EXISTS says it directly
  3. The NOT IN trap
  4. EXISTS keeps rows that do have a match
  5. Match on every key column