1970, The Relational Database Model was invented by Dr.E.F.Codd based on the Mathematical SET Theory, Predicate Logic, Relational Algebra Theory and Tuple Relational Calculus Theory. SET is a collection of objects that can be define with different types of elements in an unordered format and category the elements like Relation, Attribute and Tuple.
Predicate Logic is a Symbolic Formal System that helps to define distinguished mathematical formula with variable, existential and universal quantifier elements. Relational Algebra invented from first-order logic (Predicate Logic) that helps to define one or more Relations and operate through Relational Algebra Operators to produced new Relation is called "Closure".
Tuple Relational Calculus was invented by Dr.E.F.Codd through Relational Algebra that helps to Compose, Modify and Combine Tuples within Relation or different combination of Relations in the Relational Database Model.
Relational Database Model is a collection of objects that can be define with different types of elements in an unordered form and category the elements like Table, Column and Row that terminology invented from traditional database terminology File, Field and Record.
Relational Database Model is helps to separate the Physical Database Structure into Logical Database Structure, mean, Database Structure can design and maintain outside of Application.
Structured Query Language developed from Codd?s Relational Calculus Theory. SQL is a Non-Procedural Language that helps to maintain Database Structure, Data and Produce SET of Information in a single operation and independently working with Application.