What problem does it solve? Standard SQL UPDATE knowledge is not enough for MariaDB: its single-table and multi-table forms follow different grammars, assignments evaluate left-to-right, and features like RETURNING, ORDER BY ... LIMIT, and PARTITION apply only to specific forms. This Skill prevents the most common mistakes LLMs make when writing or reviewing UPDATE statements against MariaDB. ## Core Features & Use Cases - Single-table vs multi-table rules: Clarifies which clauses (PARTITION, ORDER BY, LIMIT, RETURNING, FOR PORTION OF) are single-table-only and how multi-table UPDATE joins and writes across tables. - Assignment semantics: Explains left-to-right evaluation, the SIMULTANEOUS_ASSIGNMENT sql_mode for true swaps, and rows-matched-vs-changed reporting. - Version-specific features: Covers UPDATE ... RETURNING with OLD_VALUE() (since 13.0), CTEs before UPDATE (since 12.3), and updates to system-versioned and application-time-period tables. - Use Case: When asked to write a batched update that returns old and new values, produce UPDATE ... ORDER BY ... LIMIT with RETURNING OLD_VALUE(col) instead of incorrectly assuming RETURNING is unsupported or adding LIMIT to a multi-table UPDATE. ## Quick Start Write a MariaDB UPDATE statement that decrements an account balance and returns the old and new balance values.
