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
The draft groups one column and keeps groups whose count is greater than one. That is a read. It does not delete rows.
Do not add a DELETE during the reading. Do not delete rows you have not copied. A delete, if the ticket later allows one, names the key and lands on a copy first.
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.
- Name the table and the column.
- Read the SELECT.
- Do not add a DELETE.
- Save a copy before any later delete.
- Stop.
Mistakes that outlive the statement
How to Find and Delete Duplicate Rows goes wrong in a small set of ways. The list is here so the ticket can forbid them before the window.
- A DELETE added during the reading.
- Rows deleted with no copy.
- The wrong column.
- A table you do not administer.
Decisions to write down
One decision for How to Find and Delete Duplicate Rows: The SELECT was read. No DELETE was added. A copy exists before any later delete. And the table is yours.
Checks before you call it done
Confirm this before you call the change done: The table is written. The column is written. The draft is a SELECT. No DELETE was added. And the database is yours. If one of those fails, stop.
-- The draft is a SELECT with GROUP BY and HAVING.
-- Do not add a DELETE during the reading.
-- Do not delete without a copy.Before you leave the database
How to Find and Delete Duplicate Rows 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.
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