SQL query: definition
An SQL query is an instruction written in SQL (Structured Query Language) sent to a database to read, add, change or delete information.
The language that drives the store's data
SQL rests on a few key instructions: SELECT to read, INSERT to add, UPDATE to change, DELETE to remove. Every page on PrestaShop or WooCommerce triggers dozens of queries: displaying a product page queries the products table and the prices table, confirming an order inserts rows into several tables at once.
For an online retailer, understanding that SQL queries exist helps explain why some back-office actions take time, or why a poorly coded extension can slow down the whole site: a badly written query, run on every page against a catalogue of several thousand products, can severely hurt performance. It's also the language a developer uses, with care, to fix a piece of data directly in phpMyAdmin when no solution is available through the back office.
Frequently asked questions
Do you need to know how to write SQL to run a store day to day?
Can a slow SQL query explain a sluggish site?
Where can you concretely see the queries a store runs?
Describe your need in one minute
A few targeted questions so I can reply with an estimate rather than another questionnaire.