A key field is a field or set of fields (a key is then said to be a composite key) of a database (typically a relational database) table which together form a unique identifier for a database record (a table entry). The aggregate of these fields is usually referred to simply as "the key". Key fields also define searches. Relational databases enforce referential integrity of their tables by matching primary keys with foreign keys. Keys can also be distinguished in technical keys (also known as surrogate keys) and business keys (also known as natural keys or domain keys).
Sometimes programmers embed a list of key values in a non-key character string fields. Many times the values in these fields cannot be guaranteed since no database can enforce the integrity of these values.
Also see primary key and foreign key.
Famous quotes containing the words key and/or field:
“Sunshine of late afternoon—
On the glass tray
a glass pitcher, the tumbler
turned down, by which
a key is lying—And the
immaculate white bed”
—William Carlos Williams (1883–1963)
“She is as in a field a silken tent
At midday when a sunny summer breeze
Has dried the dew and all its ropes relent,”
—Robert Frost (1874–1963)