Basic SQL commands and aggregate functions: 👇
https://news.1rj.ru/str/mysqldata/32
https://news.1rj.ru/str/mysqldata/32
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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
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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
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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 👍👍
👍19❤10👏1🤣1
While certificates have its own place to prove your skills, completing a course just for the sake of certificate is not going to help you at all. So whatever courses you take up, please make sure that you learn, practice and acquire that skill.
👍23❤7
Complete SQL road map
👇👇
1.Intro to SQL
• Definition
• Purpose
• Relational DBs
• DBMS
2.Basic SQL Syntax
• SELECT
• FROM
• WHERE
• ORDER BY
• GROUP BY
3. Data Types
• Integer
• Floating-Point
• Character
• Date
• VARCHAR
• TEXT
• BLOB
• BOOLEAN
4.Sub languages
• DML
• DDL
• DQL
• DCL
• TCL
5. Data Manipulation
• INSERT
• UPDATE
• DELETE
6. Data Definition
• CREATE
• ALTER
• DROP
• Indexes
7.Query Filtering and Sorting
• WHERE
• AND
• OR Conditions
• Ascending
• Descending
8. Data Aggregation
• SUM
• AVG
• COUNT
• MIN
• MAX
9.Joins and Relationships
• INNER JOIN
• LEFT JOIN
• RIGHT JOIN
• Self-Joins
• Cross Joins
• FULL OUTER JOIN
10.Subqueries
• Subqueries used in
• Filtering data
• Aggregating data
• Joining tables
• Correlated Subqueries
11.Views
• Creating
• Modifying
• Dropping Views
12.Transactions
• ACID Properties
• COMMIT
• ROLLBACK
• SAVEPOINT
• ROLLBACK TO SAVEPOINT
13.Stored Procedures
• CREATE PROCEDURE
• ALTER PROCEDURE
• DROP PROCEDURE
• EXECUTE PROCEDURE
• User-Defined Functions (UDFs)
14.Triggers
• Trigger Events
• Trigger Execution and Syntax
15. Security and Permissions
• CREATE USER
• GRANT
• REVOKE
• ALTER USER
• DROP USER
16.Optimizations
• Indexing Strategies
• Query Optimization
17.Normalization
• 1NF(Normal Form)
• 2NF
• 3NF
• BCNF
18.Backup and Recovery
• Database Backups
• Point-in-Time Recovery
19.NoSQL Databases
• MongoDB
• Cassandra etc...
• Key differences
20. Data Integrity
• Primary Key
• Foreign Key
21.Advanced SQL Queries
• Window Functions
• Common Table Expressions (CTEs)
22.Full-Text Search
• Full-Text Indexes
• Search Optimization
23. Data Import and Export
• Importing Data
• Exporting Data (CSV, JSON)
• Using SQL Dump Files
24.Database Design
• Entity-Relationship Diagrams
• Normalization Techniques
25.Advanced Indexing
• Composite Indexes
• Covering Indexes
26.Database Transactions
• Savepoints
• Nested Transactions
• Two-Phase Commit Protocol
27.Performance Tuning
• Query Profiling and Analysis
• Query Cache Optimization
------------------ END -------------------
Some good resources to learn SQL
1.Tutorial & Courses
• Learn SQL: https://bit.ly/3FxxKPz
• Udacity: imp.i115008.net/AoAg7K
2. YouTube Channel's
• FreeCodeCamp:rb.gy/pprz73
• Programming with Mosh: rb.gy/g62hpe
3. Books
• SQL in a Nutshell: https://news.1rj.ru/str/DataAnalystInterview/158
4. SQL Interview Questions
https://news.1rj.ru/str/sqlanalyst/72
Join @free4unow_backup for more free resourses
ENJOY LEARNING 👍👍
👇👇
1.Intro to SQL
• Definition
• Purpose
• Relational DBs
• DBMS
2.Basic SQL Syntax
• SELECT
• FROM
• WHERE
• ORDER BY
• GROUP BY
3. Data Types
• Integer
• Floating-Point
• Character
• Date
• VARCHAR
• TEXT
• BLOB
• BOOLEAN
4.Sub languages
• DML
• DDL
• DQL
• DCL
• TCL
5. Data Manipulation
• INSERT
• UPDATE
• DELETE
6. Data Definition
• CREATE
• ALTER
• DROP
• Indexes
7.Query Filtering and Sorting
• WHERE
• AND
• OR Conditions
• Ascending
• Descending
8. Data Aggregation
• SUM
• AVG
• COUNT
• MIN
• MAX
9.Joins and Relationships
• INNER JOIN
• LEFT JOIN
• RIGHT JOIN
• Self-Joins
• Cross Joins
• FULL OUTER JOIN
10.Subqueries
• Subqueries used in
• Filtering data
• Aggregating data
• Joining tables
• Correlated Subqueries
11.Views
• Creating
• Modifying
• Dropping Views
12.Transactions
• ACID Properties
• COMMIT
• ROLLBACK
• SAVEPOINT
• ROLLBACK TO SAVEPOINT
13.Stored Procedures
• CREATE PROCEDURE
• ALTER PROCEDURE
• DROP PROCEDURE
• EXECUTE PROCEDURE
• User-Defined Functions (UDFs)
14.Triggers
• Trigger Events
• Trigger Execution and Syntax
15. Security and Permissions
• CREATE USER
• GRANT
• REVOKE
• ALTER USER
• DROP USER
16.Optimizations
• Indexing Strategies
• Query Optimization
17.Normalization
• 1NF(Normal Form)
• 2NF
• 3NF
• BCNF
18.Backup and Recovery
• Database Backups
• Point-in-Time Recovery
19.NoSQL Databases
• MongoDB
• Cassandra etc...
• Key differences
20. Data Integrity
• Primary Key
• Foreign Key
21.Advanced SQL Queries
• Window Functions
• Common Table Expressions (CTEs)
22.Full-Text Search
• Full-Text Indexes
• Search Optimization
23. Data Import and Export
• Importing Data
• Exporting Data (CSV, JSON)
• Using SQL Dump Files
24.Database Design
• Entity-Relationship Diagrams
• Normalization Techniques
25.Advanced Indexing
• Composite Indexes
• Covering Indexes
26.Database Transactions
• Savepoints
• Nested Transactions
• Two-Phase Commit Protocol
27.Performance Tuning
• Query Profiling and Analysis
• Query Cache Optimization
------------------ END -------------------
Some good resources to learn SQL
1.Tutorial & Courses
• Learn SQL: https://bit.ly/3FxxKPz
• Udacity: imp.i115008.net/AoAg7K
2. YouTube Channel's
• FreeCodeCamp:rb.gy/pprz73
• Programming with Mosh: rb.gy/g62hpe
3. Books
• SQL in a Nutshell: https://news.1rj.ru/str/DataAnalystInterview/158
4. SQL Interview Questions
https://news.1rj.ru/str/sqlanalyst/72
Join @free4unow_backup for more free resourses
ENJOY LEARNING 👍👍
👍18❤2
Join the elite 1% - Premium strategies and insights for exceptional growth
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👩🎓👨🎓 Real Knowledge that MATTER!
⬆️ The best channel to lift you up!
Admin: @love_data
Buy ads: https://telega.io/c/trueminds
👍4
Forwarded from Data Analytics
If you dream of becoming a data analyst, let 2025 be the year you make it happen.
Work hard, stay focused, and change your life.
Happy New Year! May this year bring you success and new opportunities 💪
Work hard, stay focused, and change your life.
Happy New Year! May this year bring you success and new opportunities 💪
❤22👍15🎉1