FETCHASSOC

FETCHASSOC is a term used to describe a fetch mode in database access libraries that returns a single row as an associative data structure. In this mode, each field is addressed by its column name, so the result is a mapping from column names (strings) to their corresponding values. This contrasts with numeric fetch modes that use column positions.

In practice, the concept appears in several languages and APIs under slightly different naming. The common variant is FETCH_ASSOC, often implemented as a constant or option such as PDO::FETCH_ASSOC in PHP or a dedicated function that returns an associative array. Some libraries also provide a direct function like fetch_assoc that yields the same result. Other modes may exist, such as FETCH_NUM (numeric indices only) or FETCH_BOTH (both numeric and associative keys).

Usage typically involves selecting fetch mode when executing a query or when retrieving results, for example by calling a fetch method with the associative option or by using a function that implicitly returns an associative mapping. If a library supports default fetch modes, setting it to FETCHASSOC ensures that all retrieved rows are accessed by column name.

Advantages of FETCHASSOC include improved readability and resilience to changes in column order, since code references fields by name rather than position. Potential drawbacks include higher memory usage compared to numeric fetch modes and the need to reference exact column names, which may require handling of case sensitivity or aliasing.

See also: FETCH_NUM, FETCH_BOTH, and database API fetch modes.