A formal model of databases proposed by
E.F. Codd in
1970.
A database is a set of tables (mathematically speaking, relations).
Queries on the tables can now be posed using standard mathematical logic.
Tables can also be manipulated in whole, with the relational algebra.
There is no explicit notion of object in this model.
But the rows (tuples) or cells (values) in the tables often represent real world objects.
This is known as the object identity problem.