Relational Algebra Expression

A sequence of relational algebra operations forms a relational algebra expression.

We may choose to use single expressions or a sequence of operations:

• $${\pi }_{\text{FNAME, LNAME, SALARY}}({\sigma }_{DNO=5}(EMPLOYEE))$$
• $$\begin{array}{rl}DEP5\_EMPS& \leftarrow {\sigma }_{DNO=5}(EMPLOYEE)\\ RESULT& \leftarrow {\pi }_{\text{FNAME, LNAME, SALARY}}(DEP5\_EMPS)\end{array}$$