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PHP
PDO Schema Existence Checks
Idempotent helpers to test whether a table, column, or index already exists — handy when writing your own migration runner without an ORM.
@admin
PHP
PDO Connection with Sensible Defaults
Open a PDO connection with all the options you almost always want: real prepared statements, exceptions on error, associative-array fetch mode, UTF-8 charset.
SQL
UPSERT — MySQL ON DUPLICATE KEY UPDATE
MySQL's flavor of upsert. Triggers when an INSERT would violate a PRIMARY KEY or UNIQUE constraint. Use `VALUES()` (or `NEW.col` in MySQL 8.0.20+) to reference the would-be-inserted row.
SQL
Generated / Computed Columns
A column whose value is derived from other columns and maintained automatically. PostgreSQL has STORED (persisted) and MySQL adds VIRTUAL (computed on read). Saves you from triggers for derived data.
SQL
UPDATE with JOIN
Update one table using values from another. Syntax varies by database — PostgreSQL uses `FROM`, MySQL puts the join in the `UPDATE` clause.