This is an original planning guide. It is not a vendor manual, an official standard, or legal advice. Example addresses use documentation ranges. Review every command before you paste it.
What this hour is for
You type two comma-separated lists. INNER is the values in both. LEFT only is the values in the first list that are missing from the second. The page does not connect to a database.
Use it to agree what a join keeps. Do not paste a production query and expect a result set. A real join still needs the tables and the keys written in the ticket.
192.0.2.10, 198.51.100.0/24, 203.0.113.0/24, and 2001:db8::/32 are documentation. example.com is a documentation name. A sample password is replaced. It is not a password you keep.
The change you can finish
Apply nothing while you are writing the note. When the lab window opens, it is one change on the database named in the ticket. Read the draft, then the database, then decide.
Rollback is the backup, the file, or the snapshot you saved first. You do not invent a rollback after the only copy is gone.
- Type two short lists.
- Read INNER.
- Read LEFT only.
- Write the key the real join will use.
- Do not query a server.
- Stop.
Mistakes that outlive the statement
SQL Joins Explained goes wrong in a small set of ways. The list is here so the ticket can forbid them before the window.
- A production query pasted as if the page would run it.
- The join key left unnamed.
- A database you do not administer.
Decisions to write down
One decision for SQL Joins Explained: Both lists are written. The key is written. Nothing was queried. And the database is yours.
Checks before you call it done
Confirm this before you call the change done: INNER and LEFT only are written. The key is written. Nothing was queried. The lists are small. And the database is yours. If one of those fails, stop.
Before you leave the database
SQL Joins Explained ends when the database in the prompt is the database in the ticket. If it is not, you are on the wrong database. Stop.
The draft stays a draft until a person has read the names in it. A generator does not log into the database. You delete a line that names a host, a database, or an account you did not write down.
192.0.2.10, 198.51.100.0/24, 203.0.113.0/24, and 2001:db8::/32 are documentation. example.com is a documentation name. They belong in the note. They are not values you leave on a database because a draft included them.
prompt-for-this is a reminder that a secret is missing. It is not a password, a key, or a token you save in the ticket or in git. A sample password in a draft is replaced. It is not a password you keep.
One change is the window. If two things move and the result is wrong, you will not know which one did it.
If the same step fails twice, stop for the day. Restore the copy you took first.
A second person reads the database name and the change aloud. If they cannot find them in the ticket, the note is not done.
This page is a planning guide. It is not a vendor manual, not an official standard, and not permission to touch a database you do not administer. You do not disable authentication, a firewall, or TLS to make a check pass.
Tools for this guide
These tools run in the browser on this site. They do not log into your machines.
Related pillar guides
More in this cluster
The pillar for this page, and the next published pages filed with it.