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课程 17 · 年级 15+
Databases and SQL: where the data lives
📖 课程
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🎯 测验——选择翻译
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✅ 本课已完成
A database is tables with rules. The user is the row, the fields are columns: id, name, email. SQL is the question language: SELECT (give), INSERT (add), UPDATE (change), DELETE (remove). On our site listings, users, cities — all live in the database. SELECT * FROM users WHERE city = "Berlin" — "show all Berlin users".
- ●SELECT name, price FROM goods WHERE price < 100 — filter
- ●Relations: the listing has user_id — "who is the author"
- ●An index is like a book index: searches millions instantly
🗄 SQL injection is when an attacker "queries" the database through an input field: '; DROP TABLE users;-- . That is why code always filters input!