MySQL cookbook

How to 99% of everything your Matomo dashboard knows is stored and retrieved from its MySQL database. Here are a half dozen useful queries:

LOOKING FOR A COLUMN BY NAME, LIMIT IT TO ONLY ONE DB
SELECT TABLE_NAME, COLUMN_NAME name FROM information_schema.columns WHERE COLUMN_NAME LIKE "%key%" AND table_schema = 'XYZfurnace_mat_jan2022';

DELETE THE CONTENTS BUT NOT THE TABLE
In SQL, to delete the rows:
TRUNCATE TABLE table_name;

INSPECT THE RAW DATA
If you want to directly check for the raw data in the SQL database you could also run a query for the date, similar to
SELECT * FROM matomo_log_visit WHERE visit_first_action_time > '2023-10-21' AND visit_first_action_time < '2023-10-22';

INSPECT RAW DATA FROM THE DASHBOARD ITSELF.
1) Dashboard >> Visitors >> Visits log    (Tableau de bord >> Visiteurs >> Journal des visites)
OR
2) Dashboard >> ⚙️  >> Platform >> API  (Tableau de bord >> ⚙️  >> Plate-forme >> API)

SEE EVERY COLUMN NAME IN THE ENTIRE DATABASE
This is a great flyby of the entire data table. You can also get the lay of the land by simpling searching online for matomo data schema. SQL feels more exciting because you're seeing it in situ.
SELECT TABLE_NAME, COLUMN_NAME name FROM information_schema.columns ORDER BY COLUMN_NAME;

SEE EVERY COLUMN NAME IN THE ENTIRE DATABASE SIMILAR TO ID VISIT
This is useful if you think you know a variable name from a cookie or from the data layer or something and you wonder where is it stored in the database.
SELECT TABLE_NAME, COLUMN_NAME name FROM information_schema.columns WHERE COLUMN_NAME LIKE '%id%visit%';

SEE HOW TO BUILD THE TABLE 
DESCRIBE matomo_log_action ;
SHOW CREATE TABLE matomo_log_action ;

MORE QUERIES
For lots of great SQL query recipes, see the official Matomo SQL cookbook:
https://matomo.org/faq/how-to/how-do-i-write-sql-queries-to-select-visitors-list-of-pageviews-searches-events-in-the-matomo-database/

How to see the scheduled tasks in Matomo.
Use SQLto see the scheduled tasks in Matomo (these run at the end of any core:archive run or can be run manually with core:run-scheduled-tasks.

1. In the db, SELECT * FROM matomo_option WHERE OPTION_NAME LIKE "%sched%" ;
2. Break the lines on semicolon.

foooo
fooooo
​barrrrrrrrrrr