Primary key
A column, or set of columns, whose value is unique for every row and identifies it: a customer number, an order ID.
A dataset with no reliable key is where duplicates come from, because nothing stops the same thing being entered twice.
Where it comes up
- Near-duplicate recordsTwo rows describe the same real thing but differ enough that an exact comparison misses them.
See also
- RecordOne row of a table: the set of values that together describe a single thing, such as one customer or one transaction.
- DeduplicationFinding records that describe the same real thing and reducing them to one.
- Entity resolutionDeciding which records refer to the same real-world person, company, or thing, when no shared identifier says so.