How to Upgrade from MySQL 5.7 to 8.0

This post details the process of upgrading from MySQL 5.7 to 8.0, covering character set changes (utf8mb4, utf8mb4_0900_ai_ci), obsolete data types (YEAR(2), ENUM, TINYTEXT/MEDIUMTEXT/LONGTEXT), authentication changes (caching_sha2_password), new reserved words, SQL mode changes (ONLY_FULL_GROUP_BY, ERROR_FOR_DIVISION_BY_ZERO, NO_ENGINE_SUBSTITUTION), C-style operator deprecation (&&, ||, !), and server error code changes. It also introduces a zero-downtime upgrade path using PlanetScale's import tool, which acts as a replica during the migration and automatically handles the upgrade to 8.0. The post emphasizes the importance of performing this upgrade before the end-of-life for MySQL 5.7.