From MediaWiki.org

[edit] SQL?

[edit] How do I run queries from a .sql file?

Select your database; Import the queries from .sql file; Execute the queries.

Use a graphical SQL program (i.e. PhpMyAdmin).

[edit] How do I write & execute command lines?

Select your database; Click on SQL tab; Write & execute the queries.

Use a graphical SQL program (i.e. PhpMyAdmin).

[edit] PHP?

[edit] What is the computer I have to command?

You need to command the server, i.e. the computer serving your MediaWiki installation.

[edit] What is the software that executes my commands?

[edit] How?

See also example: manual:maintenance scripts