A .http file is a plain text file that holds API requests. It lives next to your code and goes into Git with it, so everyone on the team has the same requests. VS Code with the free REST Client extension and Visual Studio both add a link above each request that sends it. This guide covers the format and how to send requests in each editor.
In MySQL, 'usb' = 'USB' is true, and so is 'cafe' = 'café'. That comes from the collation, the rule that decides how text compares. Add COLLATE to a comparison to change the rule for that one query. This guide shows the default on MySQL 9.7, and three other rules you can ask for.
To find rows by part of a column's text in MySQL, use LIKE with a pattern, or LOCATE with plain text. They look alike and differ in what they do with %. This guide runs both on a real table on MySQL 9.7, including the part that surprises people: searching for usb finds USB.
After an INSERT, you usually need the new row's ID. After an UPDATE or a DELETE, you want to know whether it found anything. MySQL has a function for each: LAST_INSERT_ID() and ROW_COUNT(). They're simple, with a few behaviours worth seeing. All of it is run here on MySQL 9.7.
Your table's IDs go 1, 2, 5, 7, 12, and you can't account for the missing numbers. Nothing is wrong. MySQL hands out an AUTO_INCREMENT value before it knows whether the insert will succeed, and it doesn't take the value back. Here's that happening on MySQL 9.7, in two different ways.
A query can look fine and read a whole table to answer. EXPLAIN shows you how MySQL plans to run it, without running it. On MySQL 9.7 the default output is a tree, not the old table of columns many guides still show. This guide reads that tree on real queries, on a table with about 5,000 rows.
A product row holds a CategoryId, not a category's name. A JOIN brings the two tables together, so you can read both in one result. INNER JOIN keeps only the rows that match, and LEFT JOIN keeps every row from the first table. This guide runs both on MySQL 9.7, and shows a counting mistake that's easy to make.
SELECT COUNT(*) FROM table tells you how many rows a table has. Add WHERE to count only some of them, or GROUP BY to count per category. There's one trap: COUNT(column) skips NULLs, so it can give a smaller number than you expect. All of it is run here on MySQL 9.7.
LIMIT says how many rows to return, and OFFSET says how many to skip, which is all you need to page through results. There's one catch that's easy to miss: without ORDER BY, you don't know which rows you'll get. This guide pages through a real table, and shows that happening.
DELETE removes rows, and outside a transaction there's no undo. Forgetting the WHERE empties the table. This guide shows the habits that keep it safe on MySQL 9.7: check the rows first, confirm how many went, try it in a transaction, and let the database's own guards stop mistakes.
