Questions

The photon is a type of elementary particle, the quantum of the electromagnetic field including electromagnetic radiation such as light, and the force carrier for the electromagnetic force. The photon has zero rest mass and always moves at the speed of light within a vacuum.

Himachal Pradesh state became 1st to launch a pan-India single emergency no. 112 where all kinds of immediate help can be sought in urgent matters.

Under this project, an Emergency Response Centre (ERC) has been established in Shimla along with 12 district command centres (DCCs), covering the entire state. The ERC has been integrated with police (100), fire (101), health (108) and women (1090) helpline numbers to provide emergency services through the emergency number '112'.

The kilowatt hour (kW⋅h) is a composite unit of energy equivalent to one kilowatt (1 kW) of power sustained for one hour.

One watt is equal to 1 J/s. One kilowatt hour is 3.6 megajoules.

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.

History of Shimla goes back to the period of Anglo –Gurkha war in the year 1808-09. The British connection with the area developed only after this battle between the Sikh rulers of these hills and the Gurkhas from Nepal.