Day 10: SQL Views
Guys, let’s talk about Views now — for simplifying complex queries!
A View is like a virtual table created from a query. Instead of writing the same query repeatedly, you can save it as a View and use it like a table.
Example:
CREATE VIEW HighEarners AS
SELECT name, salary
FROM Employees
WHERE salary > 50000;
SELECT * FROM HighEarners;
🎯 This saves all employees earning more than 50,000 into a View called HighEarners.
Mini Challenge:
If you had a Sales table, what View would you create to find regions with sales above 1,00,000? Drop your ideas below!
Tomorrow, we’ll explore Indexes for faster queries—don’t miss it!
#SQL #LearnSQL #DataAnalytics
Guys, let’s talk about Views now — for simplifying complex queries!
A View is like a virtual table created from a query. Instead of writing the same query repeatedly, you can save it as a View and use it like a table.
Example:
CREATE VIEW HighEarners AS
SELECT name, salary
FROM Employees
WHERE salary > 50000;
SELECT * FROM HighEarners;
🎯 This saves all employees earning more than 50,000 into a View called HighEarners.
Mini Challenge:
If you had a Sales table, what View would you create to find regions with sales above 1,00,000? Drop your ideas below!
Tomorrow, we’ll explore Indexes for faster queries—don’t miss it!
#SQL #LearnSQL #DataAnalytics
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Day 11: Speed Up Your Queries with Indexes
Guys, let’s talk about Indexes! They’re like a book’s table of contents—they help you find data faster in large tables.
Here’s how to create an Index:
CREATE INDEX idx_name ON Employees(name);
🎯 This creates an Index on the name column of the Employees table, making searches by name much quicker.
But remember, while Indexes speed up reads, they can slow down writes (like INSERT or UPDATE). Use them wisely!
Mini Challenge:
If you had a Customers table, which column(s) would you index to improve query performance? Share your thoughts below!
Tomorrow, we’ll tackle Common Table Expressions (CTEs)—a must-know for clean and reusable queries!
#SQL #LearnSQL #DataSkills
Guys, let’s talk about Indexes! They’re like a book’s table of contents—they help you find data faster in large tables.
Here’s how to create an Index:
CREATE INDEX idx_name ON Employees(name);
🎯 This creates an Index on the name column of the Employees table, making searches by name much quicker.
But remember, while Indexes speed up reads, they can slow down writes (like INSERT or UPDATE). Use them wisely!
Mini Challenge:
If you had a Customers table, which column(s) would you index to improve query performance? Share your thoughts below!
Tomorrow, we’ll tackle Common Table Expressions (CTEs)—a must-know for clean and reusable queries!
#SQL #LearnSQL #DataSkills
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Day 12: Writing Cleaner Queries with CTEs
Guys, let’s simplify complex queries with Common Table Expressions (CTEs)! They make your SQL code more readable and reusable.
Here’s how a CTE works:
WITH HighEarners AS (
SELECT name, salary
FROM Employees
WHERE salary > 50000
)
SELECT name
FROM HighEarners
WHERE salary > 70000;
🎯 This breaks the query into smaller, logical steps—perfect for complex scenarios.
Mini Challenge:
If you had a Sales table, how would you use a CTE to find regions with total sales greater than 1,00,000? Write your queries below!
Tomorrow, we’ll dive into Window Functions—get ready to level up!
#SQL #LearnSQL #DataAnalytics
Guys, let’s simplify complex queries with Common Table Expressions (CTEs)! They make your SQL code more readable and reusable.
Here’s how a CTE works:
WITH HighEarners AS (
SELECT name, salary
FROM Employees
WHERE salary > 50000
)
SELECT name
FROM HighEarners
WHERE salary > 70000;
🎯 This breaks the query into smaller, logical steps—perfect for complex scenarios.
Mini Challenge:
If you had a Sales table, how would you use a CTE to find regions with total sales greater than 1,00,000? Write your queries below!
Tomorrow, we’ll dive into Window Functions—get ready to level up!
#SQL #LearnSQL #DataAnalytics
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Day 13: Level Up with Window Functions
Guys, today’s topic is Window Functions! They allow you to perform calculations across rows, without grouping the data like aggregate functions.
Here’s an example to calculate a running total:
SELECT name, salary,
SUM(salary) OVER (ORDER BY salary) AS running_total
FROM Employees;
🎯 This calculates a running total of salaries while keeping each row visible.
Window functions are great for ranking, percentages, and trends.
Mini Challenge:
Using a Sales table, how would you calculate the rank of each region based on total sales? Share your ideas below!
Tomorrow, we’ll explore how to handle duplicate records in SQL. Don’t miss it!
#SQL #LearnSQL #DataSkills
Guys, today’s topic is Window Functions! They allow you to perform calculations across rows, without grouping the data like aggregate functions.
Here’s an example to calculate a running total:
SELECT name, salary,
SUM(salary) OVER (ORDER BY salary) AS running_total
FROM Employees;
🎯 This calculates a running total of salaries while keeping each row visible.
Window functions are great for ranking, percentages, and trends.
Mini Challenge:
Using a Sales table, how would you calculate the rank of each region based on total sales? Share your ideas below!
Tomorrow, we’ll explore how to handle duplicate records in SQL. Don’t miss it!
#SQL #LearnSQL #DataSkills
👍10❤4
Day 14: Handling Duplicates in SQL
Guys, let’s tackle duplicate records in your data—an important skill for clean and accurate results!
To identify duplicates, use GROUP BY with HAVING:
SELECT name, COUNT(*) AS count
FROM Employees
GROUP BY name
HAVING COUNT(*) > 1;
🎯 This lists all duplicate names in the Employees table.
To remove duplicates, use DISTINCT:
SELECT DISTINCT name, department
FROM Employees;
🎯 This retrieves unique combinations of name and department.
Mini Challenge:
Using a Products table, how would you find and remove duplicate product entries? Drop your queries below!
Tomorrow, we’ll summarize the journey so far and discuss how to build your own SQL projects. Stay tuned!
#SQL #LearnSQL #DataSkills
Guys, let’s tackle duplicate records in your data—an important skill for clean and accurate results!
To identify duplicates, use GROUP BY with HAVING:
SELECT name, COUNT(*) AS count
FROM Employees
GROUP BY name
HAVING COUNT(*) > 1;
🎯 This lists all duplicate names in the Employees table.
To remove duplicates, use DISTINCT:
SELECT DISTINCT name, department
FROM Employees;
🎯 This retrieves unique combinations of name and department.
Mini Challenge:
Using a Products table, how would you find and remove duplicate product entries? Drop your queries below!
Tomorrow, we’ll summarize the journey so far and discuss how to build your own SQL projects. Stay tuned!
#SQL #LearnSQL #DataSkills
👍17❤4
Day 15: Building Your Own SQL Projects
Guys, it’s time to apply everything you’ve learned so far by building your own SQL project! Projects are the best way to solidify your skills and showcase them to potential employers.
Here’s a simple project idea:
1️⃣ Use a free dataset (like Kaggle or
2️⃣ Create a database with at least two related tables, like Customers and Orders.
3️⃣ Write queries to:
Retrieve insights (e.g., total sales by region).
Use joins, aggregate functions, and CTEs.
Apply window functions for trends or rankings.
🎯 Example Query:
WITH RegionalSales AS (
SELECT region, SUM(sales) AS total_sales
FROM Sales
GROUP BY region
)
SELECT region, total_sales,
RANK() OVER (ORDER BY total_sales DESC) AS rank
FROM RegionalSales;
Mini Challenge:
What SQL project idea excites you the most? Share your ideas below!
Stay consistent, and soon, SQL will be second nature. Let me know what other concepts you want to explore next!
#SQL #LearnSQL #DataAnalytics
Guys, it’s time to apply everything you’ve learned so far by building your own SQL project! Projects are the best way to solidify your skills and showcase them to potential employers.
Here’s a simple project idea:
1️⃣ Use a free dataset (like Kaggle or
Data.gov).2️⃣ Create a database with at least two related tables, like Customers and Orders.
3️⃣ Write queries to:
Retrieve insights (e.g., total sales by region).
Use joins, aggregate functions, and CTEs.
Apply window functions for trends or rankings.
🎯 Example Query:
WITH RegionalSales AS (
SELECT region, SUM(sales) AS total_sales
FROM Sales
GROUP BY region
)
SELECT region, total_sales,
RANK() OVER (ORDER BY total_sales DESC) AS rank
FROM RegionalSales;
Mini Challenge:
What SQL project idea excites you the most? Share your ideas below!
Stay consistent, and soon, SQL will be second nature. Let me know what other concepts you want to explore next!
#SQL #LearnSQL #DataAnalytics
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Day 16: Exploring Advanced SQL Topics
Guys, now that you’ve built a foundation, let’s explore some advanced SQL topics to take your skills to the next level:
1️⃣ Stored Procedures: Write reusable blocks of SQL code.
2️⃣ Triggers: Automate actions like logging changes in a table.
3️⃣ Transaction Management: Ensure data consistency with COMMIT and ROLLBACK.
4️⃣ Performance Optimization: Learn about indexing strategies and query optimization.
Here’s a sneak peek of a stored procedure:
CREATE PROCEDURE GetHighEarners()
AS
BEGIN
SELECT name, salary
FROM Employees
WHERE salary > 70000;
END;
🎯 You can call this procedure anytime with EXEC GetHighEarners.
Mini Challenge:
Which advanced SQL topic would you like to learn first? Drop your suggestions below, and let’s deep dive!
#SQL #LearnSQL #DataSkills
Guys, now that you’ve built a foundation, let’s explore some advanced SQL topics to take your skills to the next level:
1️⃣ Stored Procedures: Write reusable blocks of SQL code.
2️⃣ Triggers: Automate actions like logging changes in a table.
3️⃣ Transaction Management: Ensure data consistency with COMMIT and ROLLBACK.
4️⃣ Performance Optimization: Learn about indexing strategies and query optimization.
Here’s a sneak peek of a stored procedure:
CREATE PROCEDURE GetHighEarners()
AS
BEGIN
SELECT name, salary
FROM Employees
WHERE salary > 70000;
END;
🎯 You can call this procedure anytime with EXEC GetHighEarners.
Mini Challenge:
Which advanced SQL topic would you like to learn first? Drop your suggestions below, and let’s deep dive!
#SQL #LearnSQL #DataSkills
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Day 17: SQL for Real-World Scenarios
Guys, today let’s discuss how SQL is used in real-world scenarios. Understanding the applications makes learning more exciting and practical!
1️⃣ E-Commerce: Analyze sales trends, customer behavior, and product performance.
Example Query:
SELECT product_name, SUM(quantity) AS total_sold
FROM Orders
GROUP BY product_name
ORDER BY total_sold DESC;
2️⃣ Finance: Monitor transactions, detect fraud, and calculate account balances.
Example Query:
SELECT account_id, SUM(amount) AS balance
FROM Transactions
GROUP BY account_id;
3️⃣ Healthcare: Manage patient records and monitor hospital performance.
Example Query:
SELECT department, COUNT(*) AS total_patients
FROM Patients
GROUP BY department;
Mini Challenge:
Which industry interests you the most, and how would you apply SQL to solve a problem in it? Share your ideas below!
Tomorrow, we’ll start exploring how to prepare for SQL interviews—don’t miss it!
#SQL #LearnSQL #DataAnalytics
Guys, today let’s discuss how SQL is used in real-world scenarios. Understanding the applications makes learning more exciting and practical!
1️⃣ E-Commerce: Analyze sales trends, customer behavior, and product performance.
Example Query:
SELECT product_name, SUM(quantity) AS total_sold
FROM Orders
GROUP BY product_name
ORDER BY total_sold DESC;
2️⃣ Finance: Monitor transactions, detect fraud, and calculate account balances.
Example Query:
SELECT account_id, SUM(amount) AS balance
FROM Transactions
GROUP BY account_id;
3️⃣ Healthcare: Manage patient records and monitor hospital performance.
Example Query:
SELECT department, COUNT(*) AS total_patients
FROM Patients
GROUP BY department;
Mini Challenge:
Which industry interests you the most, and how would you apply SQL to solve a problem in it? Share your ideas below!
Tomorrow, we’ll start exploring how to prepare for SQL interviews—don’t miss it!
#SQL #LearnSQL #DataAnalytics
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Day 18: Preparing for SQL Interviews
Guys, let’s shift gears and focus on SQL interview prep. Knowing how to tackle interview questions can set you apart!
Here’s a quick breakdown of common SQL interview topics:
1️⃣ Basic Queries: Write SELECT, WHERE, and GROUP BY queries.
Example:
SELECT department, AVG(salary) AS avg_salary
FROM Employees
GROUP BY department;
2️⃣ Joins: Understand INNER, LEFT, RIGHT, FULL, and SELF JOIN.
Example:
SELECT Orders.order_id, Customers.customer_name
FROM Orders
INNER JOIN Customers
ON Orders.customer_id = Customers.customer_id;
3️⃣ Complex Scenarios: Use CTEs, Window Functions, and Subqueries.
4️⃣ Problem Solving: Be ready to debug and optimize inefficient queries.
Mini Challenge:
What’s one SQL question you’ve faced or are curious about? Share it below, and I’ll help you crack it!
Tomorrow, we’ll go over a list of must-know SQL functions. Stay tuned!
#SQL #LearnSQL #DataSkills
Guys, let’s shift gears and focus on SQL interview prep. Knowing how to tackle interview questions can set you apart!
Here’s a quick breakdown of common SQL interview topics:
1️⃣ Basic Queries: Write SELECT, WHERE, and GROUP BY queries.
Example:
SELECT department, AVG(salary) AS avg_salary
FROM Employees
GROUP BY department;
2️⃣ Joins: Understand INNER, LEFT, RIGHT, FULL, and SELF JOIN.
Example:
SELECT Orders.order_id, Customers.customer_name
FROM Orders
INNER JOIN Customers
ON Orders.customer_id = Customers.customer_id;
3️⃣ Complex Scenarios: Use CTEs, Window Functions, and Subqueries.
4️⃣ Problem Solving: Be ready to debug and optimize inefficient queries.
Mini Challenge:
What’s one SQL question you’ve faced or are curious about? Share it below, and I’ll help you crack it!
Tomorrow, we’ll go over a list of must-know SQL functions. Stay tuned!
#SQL #LearnSQL #DataSkills
👍10❤4
Basic SQL commands and aggregate functions: 👇
https://news.1rj.ru/str/mysqldata/32
https://news.1rj.ru/str/mysqldata/32
Telegram
SQL MySQL Interviews
SQL: Mastering Queries💻
Basic commands and aggregate functions:
●CREATE – Creates a table or a database.
●SELECT – Retrieves specific data from a table.
●INSERT – Adds new records to a table.
●DELETE – Removes records.
●AVG() – Calculates the average…
Basic commands and aggregate functions:
●CREATE – Creates a table or a database.
●SELECT – Retrieves specific data from a table.
●INSERT – Adds new records to a table.
●DELETE – Removes records.
●AVG() – Calculates the average…
👍4
Day 18: Preparing for SQL Interviews
Guys, let’s shift gears and focus on SQL interview prep. Knowing how to tackle interview questions can set you apart!
Here’s a quick breakdown of common SQL interview topics:
1️⃣ Basic Queries: Write SELECT, WHERE, and GROUP BY queries.
Example:
SELECT department, AVG(salary) AS avg_salary
FROM Employees
GROUP BY department;
2️⃣ Joins: Understand INNER, LEFT, RIGHT, FULL, and SELF JOIN.
Example:
SELECT Orders.order_id, Customers.customer_name
FROM Orders
INNER JOIN Customers
ON Orders.customer_id = Customers.customer_id;
3️⃣ Complex Scenarios: Use CTEs, Window Functions, and Subqueries.
4️⃣ Problem Solving: Be ready to debug and optimize inefficient queries.
Mini Challenge:
What’s one SQL question you’ve faced or are curious about? Share it below, and I’ll help you crack it!
Tomorrow, we’ll go over a list of must-know SQL functions. Stay tuned!
#SQL #LearnSQL #DataSkills
Guys, let’s shift gears and focus on SQL interview prep. Knowing how to tackle interview questions can set you apart!
Here’s a quick breakdown of common SQL interview topics:
1️⃣ Basic Queries: Write SELECT, WHERE, and GROUP BY queries.
Example:
SELECT department, AVG(salary) AS avg_salary
FROM Employees
GROUP BY department;
2️⃣ Joins: Understand INNER, LEFT, RIGHT, FULL, and SELF JOIN.
Example:
SELECT Orders.order_id, Customers.customer_name
FROM Orders
INNER JOIN Customers
ON Orders.customer_id = Customers.customer_id;
3️⃣ Complex Scenarios: Use CTEs, Window Functions, and Subqueries.
4️⃣ Problem Solving: Be ready to debug and optimize inefficient queries.
Mini Challenge:
What’s one SQL question you’ve faced or are curious about? Share it below, and I’ll help you crack it!
Tomorrow, we’ll go over a list of must-know SQL functions. Stay tuned!
#SQL #LearnSQL #DataSkills
👍7❤1
Day 19: Must-Know SQL Functions
Guys, today we’re diving into some essential SQL functions that can make your queries powerful and efficient!
1️⃣ Aggregate Functions:
SUM(): Adds up values.
AVG(): Finds the average.
COUNT(): Counts rows.
MIN() / MAX(): Gets the smallest or largest value.
Example:
SELECT department, COUNT(*) AS num_employees, AVG(salary) AS avg_salary
FROM Employees
GROUP BY department;
2️⃣ String Functions:
CONCAT(): Combines strings.
SUBSTRING(): Extracts part of a string.
UPPER() / LOWER(): Changes case.
Example:
SELECT CONCAT(first_name, ' ', last_name) AS full_name
FROM Employees;
3️⃣ Date Functions:
NOW(): Returns the current date and time.
DATEDIFF(): Calculates the difference between dates.
YEAR() / MONTH(): Extracts year/month from a date.
Example:
SELECT name, DATEDIFF(NOW(), hire_date) AS days_employed
FROM Employees;
Mini Challenge:
Try writing a query that uses both an aggregate and a date function. Share your query below!
Tomorrow, we’ll cover SQL best practices to write clean and maintainable code. Don’t miss it!
#SQL #LearnSQL #DataSkills
Guys, today we’re diving into some essential SQL functions that can make your queries powerful and efficient!
1️⃣ Aggregate Functions:
SUM(): Adds up values.
AVG(): Finds the average.
COUNT(): Counts rows.
MIN() / MAX(): Gets the smallest or largest value.
Example:
SELECT department, COUNT(*) AS num_employees, AVG(salary) AS avg_salary
FROM Employees
GROUP BY department;
2️⃣ String Functions:
CONCAT(): Combines strings.
SUBSTRING(): Extracts part of a string.
UPPER() / LOWER(): Changes case.
Example:
SELECT CONCAT(first_name, ' ', last_name) AS full_name
FROM Employees;
3️⃣ Date Functions:
NOW(): Returns the current date and time.
DATEDIFF(): Calculates the difference between dates.
YEAR() / MONTH(): Extracts year/month from a date.
Example:
SELECT name, DATEDIFF(NOW(), hire_date) AS days_employed
FROM Employees;
Mini Challenge:
Try writing a query that uses both an aggregate and a date function. Share your query below!
Tomorrow, we’ll cover SQL best practices to write clean and maintainable code. Don’t miss it!
#SQL #LearnSQL #DataSkills
👍13❤9👏5
Day 20: SQL Best Practices for Clean Code
Guys, let’s wrap up our journey with some SQL best practices to keep your code clean, efficient, and easy to maintain!
1️⃣ Use Denoscriptive Naming:
Name your tables, columns, and variables clearly.
Example: Instead of tbl1, use SalesData.
2️⃣ Comment Your Code:
Use comments to explain complex logic.
Example:
-- Selecting the top 5 highest-paid employees
SELECT name, salary
FROM Employees
ORDER BY salary DESC
LIMIT 5;
3️⃣ Avoid SELECT *:
Specify only the columns you need to improve performance and clarity.
4️⃣ Use Aliases Wisely:
Shorten long table or column names with aliases for better readability.
Example:
SELECT e.name, d.department_name
FROM Employees e
JOIN Departments d ON e.department_id = d.department_id;
5️⃣ Consistent Formatting:
Indent your code to make it easier to read.
6️⃣ Optimize Joins:
Be mindful of the type of join and how it impacts performance.
Mini Challenge:
Revise one of your older SQL queries to apply these best practices. Share the improved version below!
That wraps up our SQL series! I hope this helped you level up your skills. What would you like to learn next?
#SQL #LearnSQL #DataSkills
Guys, let’s wrap up our journey with some SQL best practices to keep your code clean, efficient, and easy to maintain!
1️⃣ Use Denoscriptive Naming:
Name your tables, columns, and variables clearly.
Example: Instead of tbl1, use SalesData.
2️⃣ Comment Your Code:
Use comments to explain complex logic.
Example:
-- Selecting the top 5 highest-paid employees
SELECT name, salary
FROM Employees
ORDER BY salary DESC
LIMIT 5;
3️⃣ Avoid SELECT *:
Specify only the columns you need to improve performance and clarity.
4️⃣ Use Aliases Wisely:
Shorten long table or column names with aliases for better readability.
Example:
SELECT e.name, d.department_name
FROM Employees e
JOIN Departments d ON e.department_id = d.department_id;
5️⃣ Consistent Formatting:
Indent your code to make it easier to read.
6️⃣ Optimize Joins:
Be mindful of the type of join and how it impacts performance.
Mini Challenge:
Revise one of your older SQL queries to apply these best practices. Share the improved version below!
That wraps up our SQL series! I hope this helped you level up your skills. What would you like to learn next?
#SQL #LearnSQL #DataSkills
👍10👏4❤1
Since we’ve covered 20 days of engaging and educational content on SQL, it’s time to consolidate everything you’ve learned and keep the momentum going!
Bonus Day: SQL Project Ideas to Build Your Portfolio
Guys, now that you've mastered SQL fundamentals and best practices, it's time to apply your skills to real projects that can boost your portfolio! Here are a few project ideas:
1️⃣ E-commerce Sales Dashboard:
Create a dashboard that tracks total sales, top-selling products, customer demographics, and trends over time.
Use SQL queries to aggregate data from different tables and create reports.
2️⃣ Employee Management System:
Build an HR database with employee details, salaries, departments, and performance metrics.
Write queries to identify top performers, calculate average salaries, and monitor department headcounts.
3️⃣ Sales and Marketing Analytics:
Create a project that analyzes the effectiveness of marketing campaigns by comparing conversion rates, customer acquisition costs, and ROI.
4️⃣ Customer Segmentation Tool:
Design a project that segments customers based on their purchase history, location, and demographics.
Use SQL to write complex queries with CASE statements and GROUP BY for insightful segments.
5️⃣ Hospital Management Database:
Build a database with patient records, doctor assignments, treatment history, and appointment scheduling.
Create queries to find the most booked doctors, calculate average wait times, and analyze patient demographics.
Mini Challenge:
Pick one of the projects above or come up with your own idea. Start by sketching out the main tables and their relationships. Share your project plan below!
#SQL #SQLProjects #DataSkills
Bonus Day: SQL Project Ideas to Build Your Portfolio
Guys, now that you've mastered SQL fundamentals and best practices, it's time to apply your skills to real projects that can boost your portfolio! Here are a few project ideas:
1️⃣ E-commerce Sales Dashboard:
Create a dashboard that tracks total sales, top-selling products, customer demographics, and trends over time.
Use SQL queries to aggregate data from different tables and create reports.
2️⃣ Employee Management System:
Build an HR database with employee details, salaries, departments, and performance metrics.
Write queries to identify top performers, calculate average salaries, and monitor department headcounts.
3️⃣ Sales and Marketing Analytics:
Create a project that analyzes the effectiveness of marketing campaigns by comparing conversion rates, customer acquisition costs, and ROI.
4️⃣ Customer Segmentation Tool:
Design a project that segments customers based on their purchase history, location, and demographics.
Use SQL to write complex queries with CASE statements and GROUP BY for insightful segments.
5️⃣ Hospital Management Database:
Build a database with patient records, doctor assignments, treatment history, and appointment scheduling.
Create queries to find the most booked doctors, calculate average wait times, and analyze patient demographics.
Mini Challenge:
Pick one of the projects above or come up with your own idea. Start by sketching out the main tables and their relationships. Share your project plan below!
#SQL #SQLProjects #DataSkills
👍18❤7🤣1
SQL 𝗢𝗿𝗱𝗲𝗿 𝗢𝗳 𝗘𝘅𝗲𝗰𝘂𝘁𝗶𝗼𝗻 ↓
1 → FROM (Tables selected).
2 → WHERE (Filters applied).
3 → GROUP BY (Rows grouped).
4 → HAVING (Filter on grouped data).
5 → SELECT (Columns selected).
6 → ORDER BY (Sort the data).
7 → LIMIT (Restrict number of rows).
𝗖𝗼𝗺𝗺𝗼𝗻 𝗤𝘂𝗲𝗿𝗶𝗲𝘀 𝗧𝗼 𝗣𝗿𝗮𝗰𝘁𝗶𝗰𝗲 ↓
↬ Find the second-highest salary:
SELECT MAX(Salary) FROM Employees WHERE Salary < (SELECT MAX(Salary) FROM Employees);
↬ Find duplicate records:
SELECT Name, COUNT(*)
FROM Emp
GROUP BY Name
HAVING COUNT(*) > 1;
1 → FROM (Tables selected).
2 → WHERE (Filters applied).
3 → GROUP BY (Rows grouped).
4 → HAVING (Filter on grouped data).
5 → SELECT (Columns selected).
6 → ORDER BY (Sort the data).
7 → LIMIT (Restrict number of rows).
𝗖𝗼𝗺𝗺𝗼𝗻 𝗤𝘂𝗲𝗿𝗶𝗲𝘀 𝗧𝗼 𝗣𝗿𝗮𝗰𝘁𝗶𝗰𝗲 ↓
↬ Find the second-highest salary:
SELECT MAX(Salary) FROM Employees WHERE Salary < (SELECT MAX(Salary) FROM Employees);
↬ Find duplicate records:
SELECT Name, COUNT(*)
FROM Emp
GROUP BY Name
HAVING COUNT(*) > 1;
👍35❤5
Complete Roadmap to learn SQL in 2024 👇👇
1. Basic Concepts
- Understand databases and SQL.
- Learn data types (INT, VARCHAR, DATE, etc.).
2. Basic Queries
- SELECT: Retrieve data.
- WHERE: Filter results.
- ORDER BY: Sort results.
- LIMIT: Restrict results.
3. Aggregate Functions
- COUNT, SUM, AVG, MAX, MIN.
- Use GROUP BY to group results.
4. Joins
- INNER JOIN: Combine rows from two tables based on a condition.
- LEFT JOIN: Include all rows from the left table.
- RIGHT JOIN: Include all rows from the right table.
- FULL OUTER JOIN: Include all rows from both tables.
5. Subqueries
- Use nested queries for complex data retrieval.
6. Data Manipulation
- INSERT: Add new records.
- UPDATE: Modify existing records.
- DELETE: Remove records.
7. Schema Management
- CREATE TABLE: Define new tables.
- ALTER TABLE: Modify existing tables.
- DROP TABLE: Remove tables.
8. Indexes
- Understand how to create and use indexes to optimize queries.
9. Views
- Create and manage views for simplified data access.
10. Transactions
- Learn about COMMIT and ROLLBACK for data integrity.
11. Advanced Topics
- Stored Procedures: Automate complex tasks.
- Triggers: Execute actions automatically based on events.
- Normalization: Understand database design principles.
12. Practice
- Use platforms like LeetCode, HackerRank, or learnsql for hands-on practice.
Here are some free resources to learn & practice SQL 👇👇
Udacity free course- https://imp.i115008.net/AoAg7K
SQL For Data Analysis: https://news.1rj.ru/str/sqlanalyst
For Practice- https://stratascratch.com/?via=free
SQL Learning Series: https://news.1rj.ru/str/sqlspecialist/567
Top 10 SQL Projects with Datasets: https://news.1rj.ru/str/DataPortfolio/16
Join for more free resources: https://news.1rj.ru/str/free4unow_backup
ENJOY LEARNING 👍👍
1. Basic Concepts
- Understand databases and SQL.
- Learn data types (INT, VARCHAR, DATE, etc.).
2. Basic Queries
- SELECT: Retrieve data.
- WHERE: Filter results.
- ORDER BY: Sort results.
- LIMIT: Restrict results.
3. Aggregate Functions
- COUNT, SUM, AVG, MAX, MIN.
- Use GROUP BY to group results.
4. Joins
- INNER JOIN: Combine rows from two tables based on a condition.
- LEFT JOIN: Include all rows from the left table.
- RIGHT JOIN: Include all rows from the right table.
- FULL OUTER JOIN: Include all rows from both tables.
5. Subqueries
- Use nested queries for complex data retrieval.
6. Data Manipulation
- INSERT: Add new records.
- UPDATE: Modify existing records.
- DELETE: Remove records.
7. Schema Management
- CREATE TABLE: Define new tables.
- ALTER TABLE: Modify existing tables.
- DROP TABLE: Remove tables.
8. Indexes
- Understand how to create and use indexes to optimize queries.
9. Views
- Create and manage views for simplified data access.
10. Transactions
- Learn about COMMIT and ROLLBACK for data integrity.
11. Advanced Topics
- Stored Procedures: Automate complex tasks.
- Triggers: Execute actions automatically based on events.
- Normalization: Understand database design principles.
12. Practice
- Use platforms like LeetCode, HackerRank, or learnsql for hands-on practice.
Here are some free resources to learn & practice SQL 👇👇
Udacity free course- https://imp.i115008.net/AoAg7K
SQL For Data Analysis: https://news.1rj.ru/str/sqlanalyst
For Practice- https://stratascratch.com/?via=free
SQL Learning Series: https://news.1rj.ru/str/sqlspecialist/567
Top 10 SQL Projects with Datasets: https://news.1rj.ru/str/DataPortfolio/16
Join for more free resources: https://news.1rj.ru/str/free4unow_backup
ENJOY LEARNING 👍👍
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