Interview-ready notes

DBMS tools, databases, and logins

A compact guide that separates database technologies, query languages, GUI/CLI tools, and the correct way to connect before writing SQL or PL/SQL.

View login commands Back to practicals

MySQL Relational database

MongoDB Document database

SQL Query language

PL/SQL Oracle language

Connect first, query second Use MySQL CLI, mongosh, Compass, or SQL*Plus.

Tools vs Technology vs Language

Use these names correctly in interviews and practical writeups.

Name	Category	Purpose
MySQL	Database Technology	Relational database that stores data in tables.
MongoDB	Database Technology	NoSQL document database that stores JSON-like documents.
SQL	Language	Query language for relational databases.
PL/SQL	Language	Oracle procedural SQL language.
MongoDB Compass	Tool	GUI tool to manage MongoDB visually.
SQL*Plus	Tool	CLI tool to connect and manage Oracle Database.

What Stores Data?

Database engines store the actual records. Languages and tools only help you work with them.

MY MySQL

Stores relational data using databases, tables, rows, and columns.

Database engine

MO MongoDB

Stores flexible document data inside collections.

Database engine

OR Oracle

Stores enterprise relational data and supports SQL plus PL/SQL.

Database engine

Query Languages

SQL is used broadly. PL/SQL is Oracle-specific and adds procedural programming features.

SQL SQL

Used in MySQL, Oracle, PostgreSQL, SQL Server, and other relational databases.

Select, insert, update, and delete records.
Create tables, views, indexes, and relationships.

Example

SELECT * FROM users;

PL PL/SQL

Used only in Oracle. It adds variables, loops, procedures, and exception handling.

Write stored procedures and functions.
Handle procedural database logic in Oracle.

Example

BEGIN
 DBMS_OUTPUT.PUT_LINE('Hello');
END;
/

Login and Connect

You do not log in to SQL or PL/SQL. You connect to a database, then run the language.

MySQL CLI

mysql -u root -p

MySQL Remote

mysql -h localhost -P 3306 -u root -p

MongoDB CLI

mongosh

MongoDB With Auth

mongosh "mongodb://user:pass@localhost:27017"

MongoDB Compass Local

mongodb://localhost:27017

MongoDB Compass Atlas

mongodb+srv://user:pass@cluster.mongodb.net

Oracle SQL*Plus

sqlplus hr/hr@localhost:1521/XEPDB1

Oracle Admin

sqlplus sys/password as sysdba

What is AS SYSDBA?

SYSDBA is an Oracle-only administrative privilege for high-level database control.

Used for Oracle administration

Start up the database.
Shut down the database.
Run recovery tasks.
Perform full administration.

Do not use it for normal apps

Applications should use limited-privilege users, not super admin accounts.

Avoid MySQL root in apps.
Avoid Oracle SYS in apps.
Avoid MongoDB admin in apps.

Correct Thinking

Use this distinction to avoid common DBMS interview mistakes.

Wrong

Login to SQL.
Login to PL/SQL.

Correct

Login to MySQL.
Login to MongoDB.
Login to Oracle using SQL*Plus.
Then run SQL or PL/SQL.

Easy Memory Trick

One quick mapping for revision before practicals or viva.

MY MySQL

Relational database.

MO MongoDB

Document database.

SQL SQL

Query language.

PL PL/SQL

Oracle programming language.

GUI Compass

MongoDB GUI tool.

CLI SQL*Plus

Oracle CLI tool.