Relational algebra :
Defines theoretical way of manipulating table contents using relational operators
Use of relational algebra operators on existing relations produces new relations
- UNION INTERSECT
- DIFFERENCE PRODUCT
- SELECT PROJECT JOIN DIVIDE
- UNION: combines all rows from two tables, keeping out duplicate rows.
- INTERECT: yields only the rows that appear in both tables.
- DIFFERENCE: yields all rows in one table that are not found in other table.
- PRODUCT: yields all possible pairs of rows from two tables.
- SELECT (RESTRICT): yields values for all rows found in a table that satisfy a given condition.
- PROJECT: yields all value for selected attributes.
- JOIN: allows information to be combined from two or more tables.
- Natural join: links tables by selecting only the rows with common values in their common attributes.
- Left outer join: yields all of the rows in a table, including rows with now matching values from other table.
- DIVIDE: uses one single column as the divisor and one 2 column as the dividend.
Written by: Mohammed Alaslani
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