SQL (MySQL)

SQL (Structured Query Language) is a query language originally developed by IBM for relational databases.

Typical use cases

• Data retrieval (SELECT)
• Data modification (UPDATE)
• Data insertion (INSERT)
• Data deletion (DELETE)
• Defining databases, tables, and data structures

SQL and databases

• Relational databases understand SQL
• Implementations differ slightly between database engines
• Data types may vary
• Core principles are largely the same
• SQL is standardized, but MySQL has its own implementation

Important notes

WARNING

• SQL statements execute immediately
• Deletes and updates are not confirmed separately
  • Some query tools might have safety checks but it is not quaranteed
• Running DELETE in a database without any restrictions matches everything and it will delete everything
• If unsure, test DELETE conditions with SELECT first