Relational Query Languages

Declarative and Procedural

Relational Algebra Operators

• Select:
• Project:
• Union:
• Set difference:
• Set intersection:
• Cartesian product:
• Rename:

Selection of tuples (rows)

for relation r:

Selection of attributes (columns)

for relation r:

Joining two relations (Cartesian Product)

for relations r,s:

Union of two relations

for relations r, s:

Set difference

for relations r, s:

Intersection of two relations

for relations r, s:

Natural Join

for relations r, s: