Database Administration Questions

Light travels fastest in Vacuum. The fastest thing in the whole universe is the speed of light in a vacuum like outer space. It is about 2.99 x 10⁸ m/s. 

A data structure is a specialized format for organizing and storing data. General data structure types include the array, the file, the record, the table, the tree, and so on. Any data structure is designed to organize data to suit a specific purpose so that it can be accessed and worked with in appropriate ways.

Linear data structure: A linear data structure traverses the data elements sequentially, in which only one data element can directly be reached.

Ex: Arrays, Linked Lists, Stack, Queue, Any type of List all are linear.

Trees like Binary Tree, B Tree or B+ Tree are examples of non linear data structure.

Data types are used for declaration of variables in computer programming languages. These determine the type and size of data associated with variables.

Data types examples - int, char, float, etc...

char datatype is the least storage data type with 1 byte.

int with 2 or 4 bytes.

float with 4 bytes

double with 8 bytes.

SQL statements are broadly classified into three. They are

1. DDL – Data Definition Language

DDL is used to define the structure that holds the data. For example, Create, Alter, Drop and Truncate table.

2. DML – Data Manipulation Language

DML is used for manipulation of the data itself. Typical operations are Insert, Delete, Update and retrieving the data from the table. The Select statement is considered as a limited version of the DML, since it can't change the data in the database. But it can perform operations on data retrieved from the DBMS, before the results are returned to the calling function.

3. DCL – Data Control Language

DCL is used to control the visibility of data like granting database access and set privileges to create tables, etc. Example - Grant, Revoke access permission to the user to access data in the database.

Local :

Only available to the current Db connection for current user and are cleared when connection is closed.

Multiple users can’t share a local temporary table.

Global:

Available to any connection once created. They are cleared when the last connection is closed.

Can be shared by multiple user sessions

Ominous is the correctly spelt word in the given options. It means that giving the worrying impression that something bad is going to happen.

Memory refresh is the process of periodically reading information from an area of computer memory and immediately rewriting the read information to the same area without modification, for the purpose of preserving the information.

Memory refresh is a background maintenance process required during the operation of semiconductor dynamic random-access memory (DRAM), the most widely used type of computer memory.