If I had to start learning data analyst all over again, I'd follow this:
1- Learn SQL:
---- Joins (Inner, Left, Full outer and Self)
---- Aggregate Functions (COUNT, SUM, AVG, MIN, MAX)
---- Group by and Having clause
---- CTE and Subquery
---- Windows Function (Rank, Dense Rank, Row number, Lead, Lag etc)
2- Learn Excel:
---- Mathematical (COUNT, SUM, AVG, MIN, MAX, etc)
---- Logical Functions (IF, AND, OR, NOT)
---- Lookup and Reference (VLookup, INDEX, MATCH etc)
---- Pivot Table, Filters, Slicers
3- Learn BI Tools:
---- Data Integration and ETL (Extract, Transform, Load)
---- Report Generation
---- Data Exploration and Ad-hoc Analysis
---- Dashboard Creation
4- Learn Python (Pandas) Optional:
---- Data Structures, Data Cleaning and Preparation
---- Data Manipulation
---- Merging and Joining Data (Merging and joining DataFrames -similar to SQL joins)
---- Data Visualization (Basic plotting using Matplotlib and Seaborn)
Hope this helps you 😊
1- Learn SQL:
---- Joins (Inner, Left, Full outer and Self)
---- Aggregate Functions (COUNT, SUM, AVG, MIN, MAX)
---- Group by and Having clause
---- CTE and Subquery
---- Windows Function (Rank, Dense Rank, Row number, Lead, Lag etc)
2- Learn Excel:
---- Mathematical (COUNT, SUM, AVG, MIN, MAX, etc)
---- Logical Functions (IF, AND, OR, NOT)
---- Lookup and Reference (VLookup, INDEX, MATCH etc)
---- Pivot Table, Filters, Slicers
3- Learn BI Tools:
---- Data Integration and ETL (Extract, Transform, Load)
---- Report Generation
---- Data Exploration and Ad-hoc Analysis
---- Dashboard Creation
4- Learn Python (Pandas) Optional:
---- Data Structures, Data Cleaning and Preparation
---- Data Manipulation
---- Merging and Joining Data (Merging and joining DataFrames -similar to SQL joins)
---- Data Visualization (Basic plotting using Matplotlib and Seaborn)
Hope this helps you 😊
❤11
🛠️ Must-Know SQL Commands & Functions ✅
1. SELECT – Retrieve data
›
2. WHERE – Filter rows
›
3. ORDER BY – Sort results
›
4. GROUP BY – Aggregate data
›
5. JOIN – Combine tables
›
6. INSERT INTO – Add new data
›
7. UPDATE – Modify existing data
›
8. DELETE – Remove data
›
9. LIKE – Pattern matching
›
10. LIMIT – Restrict result rows
›
💡 Tip: Practice on real datasets. Learn JOIN and GROUP BY early—they’re game changers!
✨ Tap ❤️ if this helped you!
1. SELECT – Retrieve data
›
SELECT * FROM customers;2. WHERE – Filter rows
›
SELECT * FROM orders WHERE amount > 500;3. ORDER BY – Sort results
›
SELECT name FROM users ORDER BY age DESC;4. GROUP BY – Aggregate data
›
SELECT department, COUNT(*) FROM employees GROUP BY department;5. JOIN – Combine tables
›
SELECT a.name, b.salary FROM employees a JOIN salaries b ON a.id = b.emp_id;6. INSERT INTO – Add new data
›
INSERT INTO users (name, age) VALUES ('John', 30);7. UPDATE – Modify existing data
›
UPDATE products SET price = 100 WHERE id = 1;8. DELETE – Remove data
›
DELETE FROM logs WHERE date < '2023-01-01';9. LIKE – Pattern matching
›
SELECT * FROM customers WHERE name LIKE 'A%';10. LIMIT – Restrict result rows
›
SELECT * FROM sales LIMIT 10;💡 Tip: Practice on real datasets. Learn JOIN and GROUP BY early—they’re game changers!
✨ Tap ❤️ if this helped you!
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7 Baby Steps to Learn SQL
1. Understand the Basics: Start by learning the foundational concepts of SQL. Understand what SQL is, its role in managing databases, and basic operations like selecting data using SELECT, filtering with WHERE, and sorting with ORDER BY. Familiarize yourself with relational database management systems (RDBMS) such as MySQL, PostgreSQL, or SQLite.
2. Master CRUD Operations: Practice writing SQL queries to perform CRUD operations (Create, Read, Update, Delete). Learn how to:
Insert data using INSERT INTO.
Retrieve data with SELECT.
Update records with UPDATE.
Delete rows using DELETE.
3. Work with Functions and Aggregations: Dive into SQL functions and aggregate queries. Understand how to use functions like MIN, MAX, AVG, COUNT, and SUM. Practice grouping data with GROUP BY and filtering aggregated data using HAVING.
4. Explore Joins and Relationships: Learn to combine data from multiple tables using different types of joins (INNER JOIN, LEFT JOIN, RIGHT JOIN, FULL JOIN). Understand table relationships (one-to-one, one-to-many, many-to-many) and how to leverage them effectively in queries.
5. Write Complex Queries: Advance to writing more complex SQL queries, including subqueries, Common Table Expressions (CTEs), and nested queries. Practice scenarios like finding duplicate entries, ranking data, or retrieving hierarchical data.
6. Understand Database Design: Learn about database normalization and denormalization to design efficient database schemas. Understand primary keys, foreign keys, constraints, and indexing to optimize query performance.
7. Engage with SQL Communities: Join SQL forums, GitHub repositories, and platforms like StackOverflow, or WhatsApp's SQL community. Participate in SQL challenges on websites like HackerRank, LeetCode, or Stratascrach to sharpen your skills and get feedback from experienced developers.
Additional Tips:
- Work on real-world datasets to understand practical applications.
- Explore advanced concepts like stored procedures, triggers, and views as you progress.
- Regularly review your queries to find optimization opportunities.
I've curated essential SQL Interview Resources👇
https://whatsapp.com/channel/0029VaGgzAk72WTmQFERKh02
Share with credits: https://news.1rj.ru/str/sqlspecialist
Hope it helps :)
1. Understand the Basics: Start by learning the foundational concepts of SQL. Understand what SQL is, its role in managing databases, and basic operations like selecting data using SELECT, filtering with WHERE, and sorting with ORDER BY. Familiarize yourself with relational database management systems (RDBMS) such as MySQL, PostgreSQL, or SQLite.
2. Master CRUD Operations: Practice writing SQL queries to perform CRUD operations (Create, Read, Update, Delete). Learn how to:
Insert data using INSERT INTO.
Retrieve data with SELECT.
Update records with UPDATE.
Delete rows using DELETE.
3. Work with Functions and Aggregations: Dive into SQL functions and aggregate queries. Understand how to use functions like MIN, MAX, AVG, COUNT, and SUM. Practice grouping data with GROUP BY and filtering aggregated data using HAVING.
4. Explore Joins and Relationships: Learn to combine data from multiple tables using different types of joins (INNER JOIN, LEFT JOIN, RIGHT JOIN, FULL JOIN). Understand table relationships (one-to-one, one-to-many, many-to-many) and how to leverage them effectively in queries.
5. Write Complex Queries: Advance to writing more complex SQL queries, including subqueries, Common Table Expressions (CTEs), and nested queries. Practice scenarios like finding duplicate entries, ranking data, or retrieving hierarchical data.
6. Understand Database Design: Learn about database normalization and denormalization to design efficient database schemas. Understand primary keys, foreign keys, constraints, and indexing to optimize query performance.
7. Engage with SQL Communities: Join SQL forums, GitHub repositories, and platforms like StackOverflow, or WhatsApp's SQL community. Participate in SQL challenges on websites like HackerRank, LeetCode, or Stratascrach to sharpen your skills and get feedback from experienced developers.
Additional Tips:
- Work on real-world datasets to understand practical applications.
- Explore advanced concepts like stored procedures, triggers, and views as you progress.
- Regularly review your queries to find optimization opportunities.
I've curated essential SQL Interview Resources👇
https://whatsapp.com/channel/0029VaGgzAk72WTmQFERKh02
Share with credits: https://news.1rj.ru/str/sqlspecialist
Hope it helps :)
❤6
🔹 Top 10 SQL Functions/Commands Commonly Used in Data Analysis 📊
1️⃣ SELECT
– Used to retrieve specific columns from a table.
SELECT name, age FROM users;
2️⃣ WHERE
– Filters rows based on a condition.
SELECT × FROM sales WHERE region = 'North';
3️⃣ GROUP BY
– Groups rows that have the same values into summary rows.
SELECT region, SUM(sales) FROM sales GROUP BY region;
4️⃣ ORDER BY
– Sorts the result by one or more columns.
SELECT * FROM customers ORDER BY created_at DESC;
5️⃣ JOIN
– Combines rows from two or more tables based on a related column.
SELECT a.name, b.salary
FROM employees a
JOIN salaries b ON a.id = b.emp_id;
6️⃣ COUNT() / SUM() / AVG() / MIN() / MAX()
– Common aggregate functions for metrics and summaries.
SELECT COUNT(×) FROM orders WHERE status = 'completed';
7️⃣ HAVING
– Filters after a GROUP BY (unlike WHERE, which filters before).
SELECT department, COUNT() FROM employees GROUP BY department HAVING COUNT() > 10;
8️⃣ LIMIT
– Restricts number of rows returned.
SELECT * FROM products LIMIT 5;
9️⃣ CASE
– Implements conditional logic in queries.
SELECT name,
CASE
WHEN score >= 90 THEN 'A'
WHEN score >= 75 THEN 'B'
ELSE 'C'
END AS grade
FROM students;
🔟 DATE functions (NOW(), DATE_PART(), DATEDIFF(), etc.)
– Handle and extract info from dates.
SELECT DATE_PART('year', order_date) FROM orders;
💬 Tap ❤️ for more!
1️⃣ SELECT
– Used to retrieve specific columns from a table.
SELECT name, age FROM users;
2️⃣ WHERE
– Filters rows based on a condition.
SELECT × FROM sales WHERE region = 'North';
3️⃣ GROUP BY
– Groups rows that have the same values into summary rows.
SELECT region, SUM(sales) FROM sales GROUP BY region;
4️⃣ ORDER BY
– Sorts the result by one or more columns.
SELECT * FROM customers ORDER BY created_at DESC;
5️⃣ JOIN
– Combines rows from two or more tables based on a related column.
SELECT a.name, b.salary
FROM employees a
JOIN salaries b ON a.id = b.emp_id;
6️⃣ COUNT() / SUM() / AVG() / MIN() / MAX()
– Common aggregate functions for metrics and summaries.
SELECT COUNT(×) FROM orders WHERE status = 'completed';
7️⃣ HAVING
– Filters after a GROUP BY (unlike WHERE, which filters before).
SELECT department, COUNT() FROM employees GROUP BY department HAVING COUNT() > 10;
8️⃣ LIMIT
– Restricts number of rows returned.
SELECT * FROM products LIMIT 5;
9️⃣ CASE
– Implements conditional logic in queries.
SELECT name,
CASE
WHEN score >= 90 THEN 'A'
WHEN score >= 75 THEN 'B'
ELSE 'C'
END AS grade
FROM students;
🔟 DATE functions (NOW(), DATE_PART(), DATEDIFF(), etc.)
– Handle and extract info from dates.
SELECT DATE_PART('year', order_date) FROM orders;
💬 Tap ❤️ for more!
❤5👏1
1️⃣ What is a CTE (Common Table Expression)?
A temporary result set used for complex queries.
WITH temp AS (SELECT * FROM employees WHERE salary > 50000)
SELECT * FROM temp;
2️⃣ Difference between RANK(), DENSE_RANK(), and ROW_NUMBER()?
⦁
ROW_NUMBER(): Unique sequence number⦁
RANK(): Skips ranks for ties⦁
DENSE_RANK(): No gaps in ranking3️⃣ What is a window function?
Calculations across a set of rows related to the current row, using
OVER(PARTITION BY…).4️⃣ Difference between WHERE and HAVING?
⦁
WHERE: Filters rows before aggregation⦁
HAVING: Filters rows after aggregation5️⃣ What is indexing and how does it work?
Speeds up queries by creating fast-lookups, like a book’s index.
6️⃣ How to remove duplicate records in SQL?
SELECT DISTINCT * FROM table_name;
7️⃣ Difference between UNION and UNION ALL?
⦁
UNION: Removes duplicates⦁
UNION ALL: Includes all rows8️⃣ How to update data using JOIN?
UPDATE emp
SET emp.salary = dept.bonus
FROM emp
JOIN dept ON emp.dept_id = dept.id;
9️⃣ Explain COALESCE() vs ISNULL().
⦁
COALESCE(): Returns first non-null from a list⦁
ISNULL(): Replaces NULL with a specified value (SQL Server)🔟 What is a correlated subquery?
A subquery referencing outer query columns, executed row-by-row.
💬 Tap ❤️ for more!
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🔰 SQL Roadmap for Beginners 2025
├── 🗃 Introduction to Databases & SQL
├── 📄 SQL vs NoSQL (Just Basics)
├── 🧱 Database Concepts (Tables, Rows, Columns, Keys)
├── 🔍 Basic SQL Queries (SELECT, WHERE)
├── ✏️ Filtering & Sorting Data (ORDER BY, LIMIT)
├── 🔢 SQL Operators (IN, BETWEEN, LIKE, AND, OR)
├── 📊 Aggregate Functions (COUNT, SUM, AVG, MIN, MAX)
├── 👥 GROUP BY & HAVING Clauses
├── 🔗 SQL JOINS (INNER, LEFT, RIGHT, FULL, SELF)
├── 📦 Subqueries & Nested Queries
├── 🏷 Aliases & Case Statements
├── 🧾 Views & Indexes (Basics)
├── 🧠 Common Table Expressions (CTEs)
├── 🔄 Window Functions (ROW_NUMBER, RANK, PARTITION BY)
├── ⚙️ Data Manipulation (INSERT, UPDATE, DELETE)
├── 🧱 Data Definition (CREATE, ALTER, DROP)
├── 🔐 Constraints & Relationships (PK, FK, UNIQUE, CHECK)
├── 🧪 Real-world SQL Scenarios & Challenges
Like for detailed explanation ❤️
#sql
├── 🗃 Introduction to Databases & SQL
├── 📄 SQL vs NoSQL (Just Basics)
├── 🧱 Database Concepts (Tables, Rows, Columns, Keys)
├── 🔍 Basic SQL Queries (SELECT, WHERE)
├── ✏️ Filtering & Sorting Data (ORDER BY, LIMIT)
├── 🔢 SQL Operators (IN, BETWEEN, LIKE, AND, OR)
├── 📊 Aggregate Functions (COUNT, SUM, AVG, MIN, MAX)
├── 👥 GROUP BY & HAVING Clauses
├── 🔗 SQL JOINS (INNER, LEFT, RIGHT, FULL, SELF)
├── 📦 Subqueries & Nested Queries
├── 🏷 Aliases & Case Statements
├── 🧾 Views & Indexes (Basics)
├── 🧠 Common Table Expressions (CTEs)
├── 🔄 Window Functions (ROW_NUMBER, RANK, PARTITION BY)
├── ⚙️ Data Manipulation (INSERT, UPDATE, DELETE)
├── 🧱 Data Definition (CREATE, ALTER, DROP)
├── 🔐 Constraints & Relationships (PK, FK, UNIQUE, CHECK)
├── 🧪 Real-world SQL Scenarios & Challenges
Like for detailed explanation ❤️
#sql
❤10
🎯 Top 20 SQL Interview Questions You Must Know
SQL is one of the most in-demand skills for Data Analysts.
Here are 20 SQL interview questions that frequently appear in job interviews.
📌 Basic SQL Questions
1️⃣ What is the difference between INNER JOIN and LEFT JOIN?
2️⃣ How does GROUP BY work, and why do we use it?
3️⃣ What is the difference between HAVING and WHERE?
4️⃣ How do you remove duplicate rows from a table?
5️⃣ What is the difference between RANK(), DENSE_RANK(), and ROW_NUMBER()?
📌 Intermediate SQL Questions
6️⃣ How do you find the second highest salary from an Employee table?
7️⃣ What is a Common Table Expression (CTE), and when should you use it?
8️⃣ How do you identify missing values in a dataset using SQL?
9️⃣ What is the difference between UNION and UNION ALL?
🔟 How do you calculate a running total in SQL?
📌 Advanced SQL Questions
1️⃣1️⃣ How does a self-join work? Give an example.
1️⃣2️⃣ What is a window function, and how is it different from GROUP BY?
1️⃣3️⃣ How do you detect and remove duplicate records in SQL?
1️⃣4️⃣ Explain the difference between EXISTS and IN.
1️⃣5️⃣ What is the purpose of COALESCE()?
📌 Real-World SQL Scenarios
1️⃣6️⃣ How do you optimize a slow SQL query?
1️⃣7️⃣ What is indexing in SQL, and how does it improve performance?
1️⃣8️⃣ Write an SQL query to find customers who have placed more than 3 orders.
1️⃣9️⃣ How do you calculate the percentage of total sales for each category?
2️⃣0️⃣ What is the use of CASE statements in SQL?
React with ♥️ if you want me to post the correct answers in next posts! ⬇️
Share with credits: https://news.1rj.ru/str/sqlspecialist
Hope it helps :)
SQL is one of the most in-demand skills for Data Analysts.
Here are 20 SQL interview questions that frequently appear in job interviews.
📌 Basic SQL Questions
1️⃣ What is the difference between INNER JOIN and LEFT JOIN?
2️⃣ How does GROUP BY work, and why do we use it?
3️⃣ What is the difference between HAVING and WHERE?
4️⃣ How do you remove duplicate rows from a table?
5️⃣ What is the difference between RANK(), DENSE_RANK(), and ROW_NUMBER()?
📌 Intermediate SQL Questions
6️⃣ How do you find the second highest salary from an Employee table?
7️⃣ What is a Common Table Expression (CTE), and when should you use it?
8️⃣ How do you identify missing values in a dataset using SQL?
9️⃣ What is the difference between UNION and UNION ALL?
🔟 How do you calculate a running total in SQL?
📌 Advanced SQL Questions
1️⃣1️⃣ How does a self-join work? Give an example.
1️⃣2️⃣ What is a window function, and how is it different from GROUP BY?
1️⃣3️⃣ How do you detect and remove duplicate records in SQL?
1️⃣4️⃣ Explain the difference between EXISTS and IN.
1️⃣5️⃣ What is the purpose of COALESCE()?
📌 Real-World SQL Scenarios
1️⃣6️⃣ How do you optimize a slow SQL query?
1️⃣7️⃣ What is indexing in SQL, and how does it improve performance?
1️⃣8️⃣ Write an SQL query to find customers who have placed more than 3 orders.
1️⃣9️⃣ How do you calculate the percentage of total sales for each category?
2️⃣0️⃣ What is the use of CASE statements in SQL?
React with ♥️ if you want me to post the correct answers in next posts! ⬇️
Share with credits: https://news.1rj.ru/str/sqlspecialist
Hope it helps :)
❤4
Learn SQL from basic to advanced level in 30 days
Week 1: SQL Basics
Day 1: Introduction to SQL and Relational Databases
Overview of SQL Syntax
Setting up a Database (MySQL, PostgreSQL, or SQL Server)
Day 2: Data Types (Numeric, String, Date, etc.)
Writing Basic SQL Queries:
SELECT, FROM
Day 3: WHERE Clause for Filtering Data
Using Logical Operators:
AND, OR, NOT
Day 4: Sorting Data: ORDER BY
Limiting Results: LIMIT and OFFSET
Understanding DISTINCT
Day 5: Aggregate Functions:
COUNT, SUM, AVG, MIN, MAX
Day 6: Grouping Data: GROUP BY and HAVING
Combining Filters with Aggregations
Day 7: Review Week 1 Topics with Hands-On Practice
Solve SQL Exercises on platforms like HackerRank, LeetCode, or W3Schools
Week 2: Intermediate SQL
Day 8: SQL JOINS:
INNER JOIN, LEFT JOIN
Day 9: SQL JOINS Continued: RIGHT JOIN, FULL OUTER JOIN, SELF JOIN
Day 10: Working with NULL Values
Using Conditional Logic with CASE Statements
Day 11: Subqueries: Simple Subqueries (Single-row and Multi-row)
Correlated Subqueries
Day 12: String Functions:
CONCAT, SUBSTRING, LENGTH, REPLACE
Day 13: Date and Time Functions: NOW, CURDATE, DATEDIFF, DATEADD
Day 14: Combining Results: UNION, UNION ALL, INTERSECT, EXCEPT
Review Week 2 Topics and Practice
Week 3: Advanced SQL
Day 15: Common Table Expressions (CTEs)
WITH Clauses and Recursive Queries
Day 16: Window Functions:
ROW_NUMBER, RANK, DENSE_RANK, NTILE
Day 17: More Window Functions:
LEAD, LAG, FIRST_VALUE, LAST_VALUE
Day 18: Creating and Managing Views
Temporary Tables and Table Variables
Day 19: Transactions and ACID Properties
Working with Indexes for Query Optimization
Day 20: Error Handling in SQL
Writing Dynamic SQL Queries
Day 21: Review Week 3 Topics with Complex Query Practice
Solve Intermediate to Advanced SQL Challenges
Week 4: Database Management and Advanced Applications
Day 22: Database Design and Normalization:
1NF, 2NF, 3NF
Day 23: Constraints in SQL:
PRIMARY KEY, FOREIGN KEY, UNIQUE, CHECK, DEFAULT
Day 24: Creating and Managing Indexes
Understanding Query Execution Plans
Day 25: Backup and Restore Strategies in SQL
Role-Based Permissions
Day 26: Pivoting and Unpivoting Data
Working with JSON and XML in SQL
Day 27: Writing Stored Procedures and Functions
Automating Processes with Triggers
Day 28: Integrating SQL with Other Tools (e.g., Python, Power BI, Tableau)
SQL in Big Data: Introduction to NoSQL
Day 29: Query Performance Tuning:
Tips and Tricks to Optimize SQL Queries
Day 30: Final Review of All Topics
Attempt SQL Projects or Case Studies (e.g., analyzing sales data, building a reporting dashboard)
Since SQL is one of the most essential skill for data analysts, I have decided to teach each topic daily in this channel for free. Like this post if you want me to continue this SQL series 👍♥️
Share with credits: https://news.1rj.ru/str/sqlspecialist
Hope it helps :)
Week 1: SQL Basics
Day 1: Introduction to SQL and Relational Databases
Overview of SQL Syntax
Setting up a Database (MySQL, PostgreSQL, or SQL Server)
Day 2: Data Types (Numeric, String, Date, etc.)
Writing Basic SQL Queries:
SELECT, FROM
Day 3: WHERE Clause for Filtering Data
Using Logical Operators:
AND, OR, NOT
Day 4: Sorting Data: ORDER BY
Limiting Results: LIMIT and OFFSET
Understanding DISTINCT
Day 5: Aggregate Functions:
COUNT, SUM, AVG, MIN, MAX
Day 6: Grouping Data: GROUP BY and HAVING
Combining Filters with Aggregations
Day 7: Review Week 1 Topics with Hands-On Practice
Solve SQL Exercises on platforms like HackerRank, LeetCode, or W3Schools
Week 2: Intermediate SQL
Day 8: SQL JOINS:
INNER JOIN, LEFT JOIN
Day 9: SQL JOINS Continued: RIGHT JOIN, FULL OUTER JOIN, SELF JOIN
Day 10: Working with NULL Values
Using Conditional Logic with CASE Statements
Day 11: Subqueries: Simple Subqueries (Single-row and Multi-row)
Correlated Subqueries
Day 12: String Functions:
CONCAT, SUBSTRING, LENGTH, REPLACE
Day 13: Date and Time Functions: NOW, CURDATE, DATEDIFF, DATEADD
Day 14: Combining Results: UNION, UNION ALL, INTERSECT, EXCEPT
Review Week 2 Topics and Practice
Week 3: Advanced SQL
Day 15: Common Table Expressions (CTEs)
WITH Clauses and Recursive Queries
Day 16: Window Functions:
ROW_NUMBER, RANK, DENSE_RANK, NTILE
Day 17: More Window Functions:
LEAD, LAG, FIRST_VALUE, LAST_VALUE
Day 18: Creating and Managing Views
Temporary Tables and Table Variables
Day 19: Transactions and ACID Properties
Working with Indexes for Query Optimization
Day 20: Error Handling in SQL
Writing Dynamic SQL Queries
Day 21: Review Week 3 Topics with Complex Query Practice
Solve Intermediate to Advanced SQL Challenges
Week 4: Database Management and Advanced Applications
Day 22: Database Design and Normalization:
1NF, 2NF, 3NF
Day 23: Constraints in SQL:
PRIMARY KEY, FOREIGN KEY, UNIQUE, CHECK, DEFAULT
Day 24: Creating and Managing Indexes
Understanding Query Execution Plans
Day 25: Backup and Restore Strategies in SQL
Role-Based Permissions
Day 26: Pivoting and Unpivoting Data
Working with JSON and XML in SQL
Day 27: Writing Stored Procedures and Functions
Automating Processes with Triggers
Day 28: Integrating SQL with Other Tools (e.g., Python, Power BI, Tableau)
SQL in Big Data: Introduction to NoSQL
Day 29: Query Performance Tuning:
Tips and Tricks to Optimize SQL Queries
Day 30: Final Review of All Topics
Attempt SQL Projects or Case Studies (e.g., analyzing sales data, building a reporting dashboard)
Since SQL is one of the most essential skill for data analysts, I have decided to teach each topic daily in this channel for free. Like this post if you want me to continue this SQL series 👍♥️
Share with credits: https://news.1rj.ru/str/sqlspecialist
Hope it helps :)
❤5👍2
✅ SQL Clauses Cheat Sheet! 🧠📘
1️⃣ SELECT – Pick the columns you want
2️⃣ WHERE – Filter rows based on condition
3️⃣ ORDER BY – Sort the results
4️⃣ GROUP BY – Group rows for aggregation
5️⃣ HAVING – Filter groups after aggregation
6️⃣ LIMIT / TOP – Restrict number of rows
-- MySQL/PostgreSQL
-- SQL Server
7️⃣ DISTINCT – Remove duplicates
8️⃣ BETWEEN – Filter within a range
9️⃣ IN – Match any from a list
🔟 ALIAS (AS) – Rename columns or tables
💡 Tip: Combine clauses for powerful queries!
♥️ Double Tap if you found this helpful!
1️⃣ SELECT – Pick the columns you want
SELECT name, age FROM students;
2️⃣ WHERE – Filter rows based on condition
SELECT * FROM orders WHERE status = 'delivered';
3️⃣ ORDER BY – Sort the results
SELECT * FROM products ORDER BY price DESC;
4️⃣ GROUP BY – Group rows for aggregation
SELECT department, COUNT(*) FROM employees GROUP BY department;
5️⃣ HAVING – Filter groups after aggregation
SELECT department, COUNT(*) FROM employees
GROUP BY department HAVING COUNT(*) > 5;
6️⃣ LIMIT / TOP – Restrict number of rows
-- MySQL/PostgreSQL
SELECT * FROM sales LIMIT 10;
-- SQL Server
SELECT TOP 10 * FROM sales;
7️⃣ DISTINCT – Remove duplicates
SELECT DISTINCT city FROM customers;
8️⃣ BETWEEN – Filter within a range
SELECT * FROM invoices WHERE amount BETWEEN 100 AND 500;
9️⃣ IN – Match any from a list
SELECT * FROM users WHERE role IN ('admin', 'manager');
🔟 ALIAS (AS) – Rename columns or tables
SELECT name AS EmployeeName FROM employees;
💡 Tip: Combine clauses for powerful queries!
♥️ Double Tap if you found this helpful!
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20 medium-level SQL interview questions:
1. Write a SQL query to find the second-highest salary.
2. How would you optimize a slow SQL query?
3. What is the difference between INNER JOIN and OUTER JOIN?
4. Write a SQL query to find the top 3 departments with the highest average salary.
5. How do you handle duplicate rows in a SQL query?
6. Write a SQL query to find the employees who have the same name and work in the same department.
7. What is the difference between UNION and UNION ALL?
8. Write a SQL query to find the departments with no employees.
9. How do you use indexing to improve SQL query performance?
10. Write a SQL query to find the employees who have worked for more than 5 years.
11. What is the difference between SUBQUERY and JOIN?
12. Write a SQL query to find the top 2 products with the highest sales.
13. How do you use stored procedures to improve SQL query performance?
14. Write a SQL query to find the customers who have placed an order but have not made a payment.
15. What is the difference between GROUP BY and HAVING?
16. Write a SQL query to find the employees who work in the same department as their manager.
17. How do you use window functions to solve complex queries?
18. Write a SQL query to find the top 3 products with the highest average price.
19. What is the difference between TRUNCATE and DELETE?
20. Write a SQL query to find the employees who have not taken any leave in the last 6 months.
Like for detailed answers ❤️
1. Write a SQL query to find the second-highest salary.
2. How would you optimize a slow SQL query?
3. What is the difference between INNER JOIN and OUTER JOIN?
4. Write a SQL query to find the top 3 departments with the highest average salary.
5. How do you handle duplicate rows in a SQL query?
6. Write a SQL query to find the employees who have the same name and work in the same department.
7. What is the difference between UNION and UNION ALL?
8. Write a SQL query to find the departments with no employees.
9. How do you use indexing to improve SQL query performance?
10. Write a SQL query to find the employees who have worked for more than 5 years.
11. What is the difference between SUBQUERY and JOIN?
12. Write a SQL query to find the top 2 products with the highest sales.
13. How do you use stored procedures to improve SQL query performance?
14. Write a SQL query to find the customers who have placed an order but have not made a payment.
15. What is the difference between GROUP BY and HAVING?
16. Write a SQL query to find the employees who work in the same department as their manager.
17. How do you use window functions to solve complex queries?
18. Write a SQL query to find the top 3 products with the highest average price.
19. What is the difference between TRUNCATE and DELETE?
20. Write a SQL query to find the employees who have not taken any leave in the last 6 months.
Like for detailed answers ❤️
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SQL isn't easy!
It’s the powerful language that helps you manage and manipulate data in databases.
To truly master SQL, focus on these key areas:
0. Understanding the Basics: Get comfortable with SQL syntax, data types, and basic queries like SELECT, INSERT, UPDATE, and DELETE.
1. Mastering Data Retrieval: Learn advanced SELECT statements, including JOINs, GROUP BY, HAVING, and subqueries to retrieve complex datasets.
2. Working with Aggregation Functions: Use functions like COUNT(), SUM(), AVG(), MIN(), and MAX() to summarize and analyze data efficiently.
3. Optimizing Queries: Understand how to write efficient queries and use techniques like indexing and query execution plans for performance optimization.
4. Creating and Managing Databases: Master CREATE, ALTER, and DROP commands for building and maintaining database structures.
5. Understanding Constraints and Keys: Learn the importance of primary keys, foreign keys, unique constraints, and indexes for data integrity.
6. Advanced SQL Techniques: Dive into CASE statements, CTEs (Common Table Expressions), window functions, and stored procedures for more powerful querying.
7. Normalizing Data: Understand database normalization principles and how to design databases to avoid redundancy and ensure consistency.
8. Handling Transactions: Learn how to use BEGIN, COMMIT, and ROLLBACK to manage transactions and ensure data integrity.
9. Staying Updated with SQL Trends: The world of databases evolves—stay informed about new SQL functions, database management systems (DBMS), and best practices.
⏳ With practice, hands-on experience, and a thirst for learning, SQL will empower you to unlock the full potential of data!
You can read detailed article here
I've curated essential SQL Interview Resources👇
https://news.1rj.ru/str/mysqldata
Share with credits: https://news.1rj.ru/str/sqlspecialist
Hope it helps :)
It’s the powerful language that helps you manage and manipulate data in databases.
To truly master SQL, focus on these key areas:
0. Understanding the Basics: Get comfortable with SQL syntax, data types, and basic queries like SELECT, INSERT, UPDATE, and DELETE.
1. Mastering Data Retrieval: Learn advanced SELECT statements, including JOINs, GROUP BY, HAVING, and subqueries to retrieve complex datasets.
2. Working with Aggregation Functions: Use functions like COUNT(), SUM(), AVG(), MIN(), and MAX() to summarize and analyze data efficiently.
3. Optimizing Queries: Understand how to write efficient queries and use techniques like indexing and query execution plans for performance optimization.
4. Creating and Managing Databases: Master CREATE, ALTER, and DROP commands for building and maintaining database structures.
5. Understanding Constraints and Keys: Learn the importance of primary keys, foreign keys, unique constraints, and indexes for data integrity.
6. Advanced SQL Techniques: Dive into CASE statements, CTEs (Common Table Expressions), window functions, and stored procedures for more powerful querying.
7. Normalizing Data: Understand database normalization principles and how to design databases to avoid redundancy and ensure consistency.
8. Handling Transactions: Learn how to use BEGIN, COMMIT, and ROLLBACK to manage transactions and ensure data integrity.
9. Staying Updated with SQL Trends: The world of databases evolves—stay informed about new SQL functions, database management systems (DBMS), and best practices.
⏳ With practice, hands-on experience, and a thirst for learning, SQL will empower you to unlock the full potential of data!
You can read detailed article here
I've curated essential SQL Interview Resources👇
https://news.1rj.ru/str/mysqldata
Share with credits: https://news.1rj.ru/str/sqlspecialist
Hope it helps :)
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Top 5 SQL Functions
1. SELECT Statement:
- Function: Retrieving data from one or more tables.
- Example:
2. COUNT Function:
- Function: Counts the number of rows that meet a specified condition.
- Example:
3. SUM Function:
- Function: Calculates the sum of values in a numeric column.
- Example:
4. AVG Function:
- Function: Computes the average value of a numeric column.
- Example:
5. GROUP BY Clause:
- Function: Groups rows that have the same values in specified columns into summary rows.
- Example:
These functions are fundamental in SQL and are frequently used for various data manipulation tasks, including data retrieval, aggregation, and analysis.
1. SELECT Statement:
- Function: Retrieving data from one or more tables.
- Example:
SELECT column1, column2 FROM table WHERE condition;2. COUNT Function:
- Function: Counts the number of rows that meet a specified condition.
- Example:
SELECT COUNT(column) FROM table WHERE condition;3. SUM Function:
- Function: Calculates the sum of values in a numeric column.
- Example:
SELECT SUM(column) FROM table WHERE condition;4. AVG Function:
- Function: Computes the average value of a numeric column.
- Example:
SELECT AVG(column) FROM table WHERE condition;5. GROUP BY Clause:
- Function: Groups rows that have the same values in specified columns into summary rows.
- Example:
SELECT column, AVG(numeric_column) FROM table GROUP BY column;These functions are fundamental in SQL and are frequently used for various data manipulation tasks, including data retrieval, aggregation, and analysis.
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SQL interview questions with answers 😄👇
1. Question: What is SQL?
Answer: SQL (Structured Query Language) is a programming language designed for managing and manipulating relational databases. It is used to query, insert, update, and delete data in databases.
2. Question: Differentiate between SQL and MySQL.
Answer: SQL is a language for managing relational databases, while MySQL is an open-source relational database management system (RDBMS) that uses SQL as its language.
3. Question: Explain the difference between INNER JOIN and LEFT JOIN.
Answer: INNER JOIN returns rows when there is a match in both tables, while LEFT JOIN returns all rows from the left table and the matched rows from the right table, filling in with NULLs for non-matching rows.
4. Question: How do you remove duplicate records from a table?
Answer: Use the
5. Question: What is a subquery in SQL?
Answer: A subquery is a query nested inside another query. It can be used to retrieve data that will be used in the main query as a condition to further restrict the data to be retrieved.
6. Question: Explain the purpose of the GROUP BY clause.
Answer: The GROUP BY clause is used to group rows that have the same values in specified columns into summary rows, like when using aggregate functions such as COUNT, SUM, AVG, etc.
7. Question: How can you add a new record to a table?
Answer: Use the
8. Question: What is the purpose of the HAVING clause?
Answer: The HAVING clause is used in combination with the GROUP BY clause to filter the results of aggregate functions based on a specified condition.
9. Question: Explain the concept of normalization in databases.
Answer: Normalization is the process of organizing data in a database to reduce redundancy and improve data integrity. It involves breaking down tables into smaller, related tables.
10. Question: How do you update data in a table in SQL?
Answer: Use the
Here is an amazing resources to learn & practice SQL: https://bit.ly/3FxxKPz
Share with credits: https://news.1rj.ru/str/sqlspecialist
Hope it helps :)
1. Question: What is SQL?
Answer: SQL (Structured Query Language) is a programming language designed for managing and manipulating relational databases. It is used to query, insert, update, and delete data in databases.
2. Question: Differentiate between SQL and MySQL.
Answer: SQL is a language for managing relational databases, while MySQL is an open-source relational database management system (RDBMS) that uses SQL as its language.
3. Question: Explain the difference between INNER JOIN and LEFT JOIN.
Answer: INNER JOIN returns rows when there is a match in both tables, while LEFT JOIN returns all rows from the left table and the matched rows from the right table, filling in with NULLs for non-matching rows.
4. Question: How do you remove duplicate records from a table?
Answer: Use the
DISTINCT keyword in a SELECT statement to retrieve unique records. For example: SELECT DISTINCT column1, column2 FROM table;5. Question: What is a subquery in SQL?
Answer: A subquery is a query nested inside another query. It can be used to retrieve data that will be used in the main query as a condition to further restrict the data to be retrieved.
6. Question: Explain the purpose of the GROUP BY clause.
Answer: The GROUP BY clause is used to group rows that have the same values in specified columns into summary rows, like when using aggregate functions such as COUNT, SUM, AVG, etc.
7. Question: How can you add a new record to a table?
Answer: Use the
INSERT INTO statement. For example: INSERT INTO table_name (column1, column2) VALUES (value1, value2);8. Question: What is the purpose of the HAVING clause?
Answer: The HAVING clause is used in combination with the GROUP BY clause to filter the results of aggregate functions based on a specified condition.
9. Question: Explain the concept of normalization in databases.
Answer: Normalization is the process of organizing data in a database to reduce redundancy and improve data integrity. It involves breaking down tables into smaller, related tables.
10. Question: How do you update data in a table in SQL?
Answer: Use the
UPDATE statement to modify existing records in a table. For example: UPDATE table_name SET column1 = value1 WHERE condition;Here is an amazing resources to learn & practice SQL: https://bit.ly/3FxxKPz
Share with credits: https://news.1rj.ru/str/sqlspecialist
Hope it helps :)
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