IT Trainer Questions

A Donut or Doughnut. Anything in the shape of a torus.

MAC - Media Access Control, address is a globally unique identifier assigned to network devices, and therefore it is often referred to as hardware or physical address.

MAC addresses are 6-byte (48-bits) in length, and are written in MM:MM:MM:SS:SS:SS format.

The difference between Union and Union all is that Union all will not eliminate duplicate rows, instead it just pulls all rows from all tables fitting your query specifics and combines them into a table. A UNION statement effectively does a SELECT DISTINCT on the results set.

Anything larger and the computer would need to break the number into smaller pieces.

16-bit is a computer hardware device or software program capable of transferring 16 bits of data at a time.

Today, 16-bit hardware and software has been replaced by 32-bit and 64-bit alternatives, which give the computer more memory to work with; increasing overall performance.

For example, early computer processors (e.g., 8088 and 80286) were 16-bit processors, meaning they were capable of working with 16-bit binary numbers (decimal number up to 65,535).

Ctrl + F is a shorcut keyword and it is used for searching the word you want in the large document in the M.S. Word.

Operating system is the most common type of System software.

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.