Data base:

RDBMS: Relational Data Base Management System

Q: What is Database (DB)?
Ans: It is place holder with systematic and structural way of storing the data. Especially in the form of rows and columns.
Ex: Flat file, File upload, insert the record etc


Q: Why do we need DB?
Ans: to store the user Data or information.


Q: How to work with DB?
Ans: in order to interact with DB we need to know the SQL language.


Q: What is SQL?
Ans: Structured Query Language. Which is used to interact and perform DB operations.


Q: DB vendors?
Ans: Oracle, DB2, SQL server, Timber, Mongo DB, MySQL, PostGreSQL etc 


Q: how to check oracle is installed in this PC?
Ans: go to run (Wnd + R)-> type cmd & click OK button. It will open the command prompt.
type SQLPLUS in the command prompt & press ENTER button. If it asks for login that means oracle is installed.


Q: Oracle versions?
Ans:
8i, 9i, 10g, 11g, 12g etc. We are using oracle 11g version.


Q: Oracle licence type?
Ans:
1. Express Edition (free)
2. Enterprise edition
3. Server


Q: Does SQL is case sensitive?
Ans: No. It is Case insensitive


Q: How to download & install Oracle Express Edition?
Ans: Download oracle 11g express edition & double click on setup.exe file.

https://www.oracle.com/database/technologies/xe-prior-release-downloads.html

1. Go to the above url
2. Select the window x64 bit
3. Click on download, it will ask you to register.
4. Register to oracle website & again click and open the download link
5. Once the software is downloaded, it is in the .zip format
6. Extract the .zip file-->double click on the setup.exe file
7. Install the software
Note: It will ask only password. Enter the password and confirm the same by re-entering the same password 
Note: In oracle express edition the default schema/User will be SYS & system.


Q: How to login to oracle Expression edition?
Ans:
case1: using windows command prompt:
open command prompt (Wnd + R-->cmd-->ENTER)-->Type below command:
SQLPLUS <username>/<password> and press ENTER


case2: using oracle command prompt (Run SQL Command Line):
open oracle command prompt (go to start--> seach for "Run SQL Command Line"--> open it)-->Type below command:
conn <username>/<password> and press ENTER


case3: using clients/Third party tools
Ex: SQL Developer, Toad, SQL workbench, DBeaver etc



Q: As we are using free oracle (Express edition), here we have 2 db tables for practice purpose.
1. EMP
2. DEPT


Q: How to run .sql file in command prompt?
Ans: Login to oracle through cmd prompt.

@ <path of the .sql file>


Q: How to see the table structure/metadata? OR How to check table exist/not?
Ans:
describe <tableName>;
desc <tableName>;


Q: How to see the table data?
Ans:
select * from <tableName>;



Q: In a DB, how the data are stored?
Ans:
In Every DB, the data are stored in the tables (row & columns) format.
A DB can have 'n' number of tables.


Q: SQL is a non-procedural language.
Ans: Yes
