دانلود رایگان پاورپوینت پردازش پرس و جو و بهینه سازی (انگلیسی)

Relational algebra

Relational algebra = language for querying the relational model. It is a procedural language = how to carry out the query, as opposed to what to retrieve = declarative language, i.e. relational calculus. Basis for SQL. Basis for implementation and optimization of queries.