The Free On-line Dictionary of Computing (30 December 2018):

relational data model
relational model

    (Or "relational model") A data model introduced
   by E.F. Codd in 1970, particularly well suited for business
   data management.  In this model, data are organised in
   tables.  The set of names of the columns is called the
   "schema" of the table.

   Here is an example table with the schema (account number,
   amount) and 3 lines.

    account number     amount
    --------------  ---------
    12343243546456  +30000.00
    23149875245824   +2345.33
    18479827492874    -123.25

   The data can be manipulated using a relational algebra.
   SQL is a standard language for talking to a database built
   on the relational model (a "relational database").

   ["A relational model for large shared data banks"
   Communications of ACM 13:6, pp 377-387].

   (1998-10-05)