Questions

A Subquery or Inner query or a Nested query is a query within another SQL query and embedded within the WHERE clause.

Subqueries are most frequently used with the SELECT statement. The basic syntax is as follows::

SELECT column_name [, column_name ]
FROM table1 [, table2 ]
WHERE column_name OPERATOR
(SELECT column_name [, column_name ]
FROM table1 [, table2 ]
[WHERE])

A subquery is used to return data that will be used in the main query as a condition to further restrict the data to be retrieved.

Subqueries can be used with the SELECT, INSERT, UPDATE, and DELETE statements along with the operators like =, <, >, >=, <=, IN, BETWEEN, etc.

There are a few rules that subqueries must follow −

1. Subqueries must be enclosed within parentheses.

2. A subquery can have only one column in the SELECT clause, unless multiple columns are in the main query for the subquery to compare its selected columns.

3. An ORDER BY command cannot be used in a subquery, although the main query can use an ORDER BY. The GROUP BY command can be used to perform the same function as the ORDER BY in a subquery.

4. Subqueries that return more than one row can only be used with multiple value operators such as the IN operator.

5. The SELECT list cannot include any references to values that evaluate to a BLOB, ARRAY, CLOB, or NCLOB.

6. A subquery cannot be immediately enclosed in a set function.

7. The BETWEEN operator cannot be used with a subquery. However, the BETWEEN operator can be used within the subquery.

The southern state Telangana decided to make way for electric cars to promote non-polluting vehicles.

Hub works on layer 1 i.e, physical layer.

Global warming is the increase in the earth’s average temperature due to release of several greenhouse gases to the atmosphere by humans. Global warming is affecting many parts of the world.

Natural Causes include :

1. Solar Activity

2. Melting Permafrost

3. Forest Fires 

Human made causes include :

1. Deforestation

2. Overpopulation

3. Landfills

4. Mining

5. Fertilizer Use

In biology, Homology is defined as any characteristic of biological organisms that is derived from a common ancestor. 

Hence, Homology is evidence of Common ancestry.

A Focus of an earthquake is the location where the earthquake begins. The ground ruptures at this spot, then seismic waves radiate outward in all directions.

At this focus point, the release of energy due to faulting actually occurs during an earthquake. The point directly above the focus on the surface is called Epicenter.

The focus is also called as Hypocenter as it is the synonym of the focus.