Chapter 6, Problem 6.1RQ

Define each of the following terms:

1. dynamic view
2. correlated subquery
3. materialized view
4. base table
5. Join
6. equi-join
7. self join
8. outer join
9. virtualized table

Program Plan Intro

(a)

Define Dynamic View.

Explanation of Solution

Dynamic view is not a temporary table and its definition is stored in the system catalog. The content of this view is materialized as a result of an SQL query that uses the view.

Program Plan Intro

(b)

Define Correlated Subquery.

Explanation of Solution

In SQL, Correlated subquery is a subquery that processes the inner query depending on the data from the outer query.

Program Plan Intro

(c)

Define Materialized View.

Explanation of Solution

Materialized view is different from the dynamic view. It is stored on a disk and is refreshed when used or at some intervals. Copies of data is created in the same way as dynamic view.

Program Plan Intro

(d)

Define Base Table.

Explanation of Solution

Base Table is a table from relational data model that contains the inserted raw data. These tables are correspond to those relations which are identified in the conceptual schema of database.

Program Plan Intro

(e)

Define Join.

Explanation of Solution

Join is a relational operation that is used to combine two tables with a common domain into a single view or table.

Program Plan Intro

(f)

Define Equi Join.

Explanation of Solution

Equi-join is a form of join in which the joining is performed on the basis of the equality between values in the columns that are common. Those common columns appear in the result table redundantly.

Program Plan Intro

(g)

Define Self Join.

Explanation of Solution

Sometimes a join requires match of rows in a table with other rows in that same table which means joining of table with itself. This is known as self join.

Program Plan Intro

(h)

Define Outer Join.

Explanation of Solution

Outer join is a form of join in which those rows are not included in the resulting table that do not have similar values in the common columns.

Program Plan Intro

(i)

Define Virtualized Table.

Explanation of Solution

Virtualized tables are not maintained as the tables with real data. These are constructed automatically as the requirement of a DBMS.