The Watchtower conquered - summary

Congratulations, @name! You have stood at the top of the Watchtower and mastered the most powerful tools of the Great Library. Here is what you already know:

What you have learned

• Transactions -

  START TRANSACTION

  ,

  COMMIT

  ,

  ROLLBACK

  - "all or nothing" operations.
• The ACID principles - Atomicity, Consistency, Isolation, Durability - the pillars of trust in a database.
• Views -

  CREATE VIEW ... AS SELECT ...

  - saved queries used like virtual tables.
• CTEs -

  WITH name AS (...) SELECT ...

  - clear, step-by-step queries.
• Window functions -

  ROW_NUMBER()

  ,

  RANK()

  with

  OVER (... PARTITION BY ...)

  - numbering and rankings.

Quick cheat sheet

| Tool | What for? | |------|-----------| |

START TRANSACTION ... COMMIT

| consistent group operations | |

ROLLBACK

| undoing a failed transaction | |

CREATE VIEW

| a saved, reusable query | |

WITH ... AS

| a clear, complex SELECT | |

ROW_NUMBER() OVER (...)

| numbering and rankings |

What's next?

You now have the full set of the Keeper's skills. You can protect the integrity of the data and draw the deepest conclusions from it. In the next location you will combine all your knowledge into your Magnum Opus - you will design your own treasury of data from scratch. The Library is in good hands!