SQL Notes

About This Repository

This repository contains my SQL learning notes created while building practical skills for IT Support, Application Support, Reporting, and System Administration roles.

The purpose of this repository is to document my learning clearly, revise SQL concepts quickly, and practice queries commonly used in workplace support and reporting tasks.

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Learning Goal

My goal is to become comfortable with database fundamentals, data retrieval, filtering, sorting, grouping, joins, subqueries, and data modification.

These skills are useful for roles such as:

• Application Support Engineer
• Technical Support Engineer
• IT Support Engineer
• Reporting Executive
• MIS Executive
• Operations Support Executive
• Junior Database Support Engineer

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Current Learning Status

I am currently learning SQL from the basics and documenting each topic in a simple, recall-friendly format.

The focus is on:

• Understanding database concepts
• Writing clear SQL queries
• Retrieving required data
• Filtering and sorting records
• Preparing reports
• Troubleshooting data-related issues
• Practising support-based SQL scenarios
• Preparing for SQL interview questions

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Topics Covered

• Database Fundamentals
• Tables, Rows, and Columns
• SQL Syntax
• SELECT Queries
• Filtering with WHERE
• Sorting Data
• Limiting Query Results
• Aggregate Functions
• GROUP BY and HAVING
• Joins
• Subqueries
• CRUD Operations
• Primary Keys and Foreign Keys
• Normalization Basics
• Helpdesk-Style SQL Practice
• SQL Interview Questions

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Repository Structure

File	Description
01-database-basics.md	Database, table, row, column, and DBMS fundamentals
02-select-statement.md	Retrieving data using SELECT queries
03-where-filtering.md	Filtering records using conditions and operators
04-order-by-limit.md	Sorting and limiting query results
05-aggregate-functions.md	Using COUNT, SUM, AVG, MIN, and MAX
06-group-by-having.md	Grouping records and filtering grouped results
07-joins.md	Combining data using INNER, LEFT, and RIGHT JOIN
08-subqueries.md	Using queries inside other queries
09-crud-operations.md	Creating, reading, updating, and deleting records
10-keys-and-normalization.md	Primary keys, foreign keys, and normalization basics
11-helpdesk-practice-queries.md	Practical support and reporting query examples
12-sql-interview-questions.md	Common SQL interview questions and answers

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SQL Learning Method

For each topic, I document:

• What the concept means
• Why it is used
• Basic syntax
• Practical query examples
• Expected output
• Common mistakes
• Quick recall notes
• Interview-style questions

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Example Format

SELECT employee_name, department
FROM employees
WHERE status = 'Active';

Purpose:

Retrieves the name and department of active employees.

Recall:

• SELECT chooses columns.
• FROM chooses the table.
• WHERE filters records.

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Repository Purpose

This repository helps me:

• Revise SQL concepts quickly
• Practise writing queries
• Improve data-handling skills
• Understand database-backed applications
• Prepare support and reporting queries
• Practise technical documentation
• Track my SQL learning progress
• Show recruiters my interest in application support and data-related IT roles

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Practice Environment

• Database: MySQL
• Query Language: SQL
• Learning Style: Practical queries with recall notes
• Documentation Format: Markdown

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Progress Tracker

• Database fundamentals
• SELECT statements
• WHERE filtering
• ORDER BY and LIMIT
• Aggregate functions
• GROUP BY and HAVING
• Joins
• Subqueries
• CRUD operations
• Keys and normalization
• Helpdesk-style practice queries
• SQL interview questions

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Career Direction

I am learning SQL as part of my transition toward Application Support, IT Support, Reporting, Operations Support, and System Administration roles.

This repository will be updated as I continue learning and practising SQL.