Specifying Queries as Relational Expressions:
The SQUARE Data Sublanguage
This paper presents a data sublanguage called
SQUARE, intended for use in ad hoc, interactive 
problem solving by non-computer specialists. SQUARE
is based on the relational model of data, and is 
shown to be relationally complete; however, it avoids
the quantifiers and bound variables required by 
languages based on the relational calculus.  Facilities
for query, insertion, deletion, and update on 
tabular data bases are described.  A syntax is given,
and suggestions are made for alternative syntaxes, 
including a syntax based on English key words for
users with limited mathematical background.
CACM November, 1975
Boyce, R. F
Chamberlin, D. D.
King, W. F. III
