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Primary key
A primary key is a column, or set of columns, whose value uniquely identifies each row in a database table.
Prerequisite: Database table
What matters
Because it uniquely identifies a row, the primary key is what other tables reference to link related data together reliably.
Example
A 'users' table's primary key might be its 'id' column, ensuring no two users can ever share the same id value.
Common misconception
A primary key is not required to be a name or another human-readable field; it's commonly a system-generated id specifically chosen for guaranteed uniqueness.
Recall question
What property must a primary key's value always have across every row?
Keywords and related concepts
primary keyunique identifierdatabaseforeign key