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🗄️ Queries · Joins · Aggregations · DDL & DML · From Zero to Data

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🗂️ What's Inside

SQL_Learning/
│
├── 📁 basics/
│   ├── 🔰 select-queries/       → SELECT, WHERE, ORDER BY, LIMIT
│   ├── 🔤 string-functions/     → UPPER, LOWER, CONCAT, LENGTH
│   └── 🔢 numeric-functions/    → ROUND, CEIL, FLOOR, MOD
│
├── 📁 joins/
│   ├── 🔗 inner-join/           → Matching rows from both tables
│   ├── ⬅️  left-join/           → All rows from left + matched right
│   ├── ➡️  right-join/          → All rows from right + matched left
│   └── 🔄 full-outer-join/      → All rows from both tables
│
├── 📁 aggregations/
│   ├── 📊 group-by/             → GROUP BY, HAVING
│   └── 🔢 functions/            → COUNT, SUM, AVG, MIN, MAX
│
├── 📁 subqueries/               → Nested & Correlated Subqueries
│
├── 📁 ddl-dml/
│   ├── 🏗️  ddl/                 → CREATE, ALTER, DROP, TRUNCATE
│   └── ✏️  dml/                 → INSERT, UPDATE, DELETE
│
└── 📄 README.md

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📚 Topics Covered

🔰 SELECT Queries SELECT · WHERE · LIKE ORDER BY · LIMIT · DISTINCT	🔗 Joins INNER · LEFT · RIGHT FULL OUTER · SELF JOIN CROSS JOIN	📊 Aggregations COUNT · SUM · AVG MIN · MAX · GROUP BY HAVING
🔍 Subqueries Nested Queries Correlated Subqueries EXISTS · IN · ANY · ALL	🏗️ DDL CREATE TABLE · ALTER DROP · TRUNCATE Constraints	✏️ DML INSERT · UPDATE · DELETE MERGE · UPSERT
🔑 Constraints PRIMARY KEY · FOREIGN KEY UNIQUE · NOT NULL CHECK · DEFAULT	🔤 Functions String · Date · Numeric IFNULL · COALESCE CASE WHEN	🗃️ Views & Indexes CREATE VIEW CREATE INDEX Stored Procedures

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💡 Sample Query Snippets

🔗 JOIN Example

SELECT e.name, d.department_name
FROM employees e
INNER JOIN departments d ON e.dept_id = d.id
WHERE d.department_name = 'Engineering';

📊 Aggregation Example

SELECT department, COUNT(*) AS total_employees, AVG(salary) AS avg_salary
FROM employees
GROUP BY department
HAVING AVG(salary) > 50000
ORDER BY avg_salary DESC;

🔍 Subquery Example

SELECT name, salary
FROM employees
WHERE salary > (SELECT AVG(salary) FROM employees);

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📈 Learning Progress

SELECT & Filtering     ████████████████████  100% ✅
ORDER BY & LIMIT       ████████████████████  100% ✅
Joins                  ██████████████████░░   90% ✅
Aggregations           ████████████████░░░░   80% 🔄
Subqueries             ██████████████░░░░░░   70% 🔄
DDL (CREATE/ALTER)     ████████████░░░░░░░░   60% 🔄
DML (INSERT/UPDATE)    ████████████░░░░░░░░   60% 🔄
Functions              ██████████░░░░░░░░░░   50% 🔄
Views & Indexes        ██████░░░░░░░░░░░░░░   30% 🔄
Stored Procedures      ████░░░░░░░░░░░░░░░░   20% 🔄

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🛠️ Tools Used

Tool	Purpose
🔴 Oracle SQL Developer	Writing & running SQL queries
📋 SQL*Plus (Oracle CLI)	Command line database interaction
🐙 GitHub	Version control & portfolio

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👤 About Me

Xavier Varghese — Associate QA Engineer from India 🇮🇳

Learning Oracle SQL to strengthen my data querying skills for QA, test data management & automation.

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