SQL

SQL Repository

Overview

This repository contains a comprehensive set of SQL scripts organized to help you learn and practice core database concepts using an Employee database schema. The exercises span basic to advanced SQL, including DDL, DML, joins, subqueries, built-in functions, window functions, and stored procedures.

Objectives

• Learn to create and manage relational database structures
• Write queries for data retrieval, filtering, and aggregation
• Practice joins, subqueries, views, and functions
• Understand advanced topics like CTEs, procedures, and window functions

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SQL Practice Repository – Employee Database

📁 File Structure

Filename	Topic Covered
1.0.SQL	Initial setup or basic SQL intro
1.Creating_Load_Tables.sql	Creating and loading tables (DDL + DML basics)
2.Insert.sql	Inserting records into tables
3.1 Check.sql	Using CHECK constraints
3.Alter Add Drop.sql	Altering tables: ALTER, ADD, DROP
4.Select.sql	Basic SELECT statements
5.Distinct.sql	Removing duplicates with DISTINCT
6.Where.sql	Filtering data using WHERE
7.Order_by.sql	Sorting results with ORDER BY
8.Limit.sql	Limiting rows using LIMIT or TOP
9.Comparison_ope.sql	Operators like =, !=, >, <, etc.
10.Logical_ope.sql	AND, OR, NOT logical operators
11.Between.sql	Filtering between a range
12.IN operator.sql	Filtering using IN clause
13.Like.sql	Pattern matching with LIKE
14.Null.sql	Handling NULL values
15.Not_Operator.sql	Using NOT operator in queries
16.Buit_in_Function.sql	Using SQL built-in functions
17.Aggregate function.sql	SUM(), AVG(), COUNT(), MAX(), MIN()
18.Group_By.sql	Grouping results using GROUP BY
19.Having.sql	Filtering groups with HAVING
20.Alias.sql	Using aliases with AS
21.Joins.sql	INNER, LEFT, RIGHT, FULL joins
22.Subquerry.sql	Writing subqueries (nested queries)
23.ALL & Any.sql	Using ALL and ANY keywords
24.Set_Operation.sql	UNION, INTERSECT, EXCEPT
25.Update.sql	Updating existing records
26.Delete.sql	Deleting records
27.Case.sql	Using CASE for conditional logic
28.CTE.sql	Writing Common Table Expressions (WITH clause)
29.Windows_Functions.sql	ROW_NUMBER(), RANK(), LEAD(), LAG()
30.View.sql	Creating and using SQL VIEWs
31.Storage_Procedure.sql	Introduction to stored procedures
32.Functions.sql	Writing user-defined functions
33.Normalization.sql	Database normalization concepts (1NF, 2NF, 3NF, etc.)
34.Handling_JSON_&_xml.sql	Working with JSON and XML data types
ER diagram.pdf	Entity Relationship diagram for the Employee database

SQL_books

Reference materials or notes based on popular Python books.

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How to Use

1. Setup:

   • Use a SQL environment such as MySQL, PostgreSQL, SQLite, or SQL Server.
   • Load the database schema and data using 1.Creating_Load_Tables.sql.

2. Explore:

   • Run each script sequentially to master SQL fundamentals and advanced concepts.
   • Modify queries and try new examples for deeper understanding.

3. Visualize:

   • Use the included ER diagram.pdf to understand the structure and relationships.

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Prerequisites

• Basic understanding of relational databases
• Installed SQL engine (e.g., MySQL Workbench, pgAdmin, SQLite Studio)

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License

This project is open-source and available for educational use under the MIT License.

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Acknowledgements

• SQL documentation from W3Schools
• PostgreSQL Docs
• MySQL Docs
• Inspired by real-world employee database models