sql

Question 1

what is database?

Answer 1

database is a collection of data and a method for accessing and manipulating the data.
databases captures and stores the data so that we can use it.

Question 2

different databases

Answer 2

there are many databases out there because there are different types of data
and every user every company uses data in a different way.
eg:ibm, oracle, my sql, micreosoft sql server,cassandra etc.

Question 3

what is dbms

Answer 3

database management system is a software it is a program used to manage database .it receives instructions from somebody like us that wants somthing to do with the data or make changes in it.

Question 4

what is rdbms

Answer 4

relational data base management system is a subest of database management system they are most useful and most common databases.sql , sql lite. oracle uses this kind od database management system .

Question 5

sql

Answer 5

structured query language is a way to interact with database mangement system

Question 6

query

Answer 6

query is a type of instruction. queries are the ways that we are goung to put our questions and to which we want answer from the database

Question 7

what is heirarchial structure in sql

Answer 7

heirarchial structure has a parent and child node relationship .it has drawbacks and every child can only have one parent, and when you delete a parent node child node will be deleted. child node is directly connected to parent node

Question 8

what is networking modal

Answer 8

networking modal expanded on to heirarchial modal and allows many to many relationships, child entites could have multiple parents

Question 9

relational modal

Answer 9

it does’t have parent child relationships it organizes data in tables also called relations

Question 10

crud

Answer 10

create , read , update ,delete these are the things done by sql.its also going to secure the data.

Question 11

columns

Answer 11

column stores domain and constrains also called as attributes , for ex : this column has this attributes and the collection of columns is called a degree

Question 12

rows

Answer 12

rows are also called as tuples . tuple is nothing but a singular row of data .

Question 13

primary key

Answer 13

primary key uniquely identifies the data.

Question 14

foreign key

Answer 14

foreign key is a key which references prmary key of a different table

Question 15

oltp

Answer 15

online transaction process . data of tranmsactions on daily basis.these are the databases driving day to day transaction

Question 16

olap

Answer 16

online analytical process

Question 17

sql commands

Answer 17

dcl. dml , dql ,
–dcl stands for data control language.it grants and revokes access, ability to give certain access to certain dataset or revoke access to certain data.
==ddl : data definaton language ddl is used while setting up the data base . in ddl we can create ,alter , drop , rename,truncate , comment.

Question 18

dql

Answer 18

data query language contains select statement and is one that drives your world

Question 19

dml

Answer 19

data modificaton language , once we use ddl to define our database we are actually talking about the data

Question 20

why postgres sql

Answer 20

we are using postgres sql and valentina db for the course . valentina db is an ui used to manage postgres . we are using postgres as it is widely used