Database Reference
In-Depth Information
the columns in the input relation. It is denotedby symbol pi (π). We can represent the
projection operation by
T[c1, c2, …],
Where
T
is a table expression and
[c1, c2, …]
is a
column list, also called a projection list.
Syntax for the project operator is as follows:
PROJECT <table name> [<column list>]<result table>
Example 11:
In the following figure, only three columns (Product ID, Product Name, Price)
are extracted from table product.
Example 12:
To see three fields ( Product ID, Product Name, price) , we can write as:
π
product ID,Product Name,Price
(Product)
Another example Projection operator
π
Product Name
(σ
Price >1000
(student))
