IT Trainer 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.

They is incorrect when talking of the television channel.

New is redundant.

And which must have a clear antecedent.

Hence, Only Option A satisfies and clears all the flaws in the given sentence.

The standard English sentence order is Subject-Verb-Object.

For example ::

In the sentence, Why did you (S) do (V) that (O)?

ITIL Availability Management aims to define, analyze, plan, measure and improve all aspects of the availability of IT services. It is is responsible for ensuring that all IT infrastructure, processes, tools, roles etc are appropriate for the agreed availability targets.

A computer programming language is nothing but a language which is understand by the computer.

Examples of programming languages are Basic, C, Java, Python, ...

Function: A Function is a block of statement which perform some operation.

Declaring the function before using the function in program is known as implicit declaration of the function.

For Example::

int bar(void); // function (forward) declaration

int main(void) {

bar(); // bar was declared, the compiler has all the info

return foo(123); // foo not yet known; impl. decl. warning

}

// not previously declared function definition

int foo(int a) {

return a;

} 

// previously declared function definition

int bar() {

return 321;

}

There are lots of reasons behind the flood in any area but the main reason is a heavy downpour or rapid snowmelt can flood canyons with a mixture of soil, rock, and water is a major cause of floods.

When the spring times come, sometimes there's a lot of warmth that suddenly comes, especially nowadays when there are things such as global warming. So the snow melts and large amounts of water can flood the fields that are often found at the foot of a mountain or similar things.

But they may also be caused by deforestation, drainage channel modification from a landslide, earthquake or volcanic eruption. Examples include outburst floods and lahars.