Unique (disambiguation)

The word unique appears in several distinct PHP concepts:

  • array_unique(): a built-in PHP function that removes duplicate values from an array, returning only the first occurrence of each value. Comparison is by string representation by default, configurable via sort flags.

  • Unique identifier: a value that distinguishes one entity from all others within a given scope. Covers auto-increment integers, UUID, ULID, Sqids, and slugs.

  • Uniqueness constraint (SQL): a database constraint that prevents duplicate values in a column or combination of columns. Related to indexing strategy and race conditions on insert.

  • Deduplication: the broader process of detecting and discarding duplicate occurrences of an operation, message, or record, commonly applied in queues, webhooks, and distributed systems.

Related : array_unique(), Unique Identifier, Deduplication, Index For SQL, Universally Unique IDentifier (UUID), Universally Unique Lexicographically Sortable Identifier (ULID), Sqids, Duplicate