30-day Roadmap plan for SQL covers beginner, intermediate, and advanced topics ๐
Week 1: Beginner Level
Day 1-3: Introduction and Setup
1. Day 1: Introduction to SQL, its importance, and various database systems.
2. Day 2: Installing a SQL database (e.g., MySQL, PostgreSQL).
3. Day 3: Setting up a sample database and practicing basic commands.
Day 4-7: Basic SQL Queries
4. Day 4: SELECT statement, retrieving data from a single table.
5. Day 5: WHERE clause and filtering data.
6. Day 6: Sorting data with ORDER BY.
7. Day 7: Aggregating data with GROUP BY and using aggregate functions (COUNT, SUM, AVG).
Week 2-3: Intermediate Level
Day 8-14: Working with Multiple Tables
8. Day 8: Introduction to JOIN operations.
9. Day 9: INNER JOIN and LEFT JOIN.
10. Day 10: RIGHT JOIN and FULL JOIN.
11. Day 11: Subqueries and correlated subqueries.
12. Day 12: Creating and modifying tables with CREATE, ALTER, and DROP.
13. Day 13: INSERT, UPDATE, and DELETE statements.
14. Day 14: Understanding indexes and optimizing queries.
Day 15-21: Data Manipulation
15. Day 15: CASE statements for conditional logic.
16. Day 16: Using UNION and UNION ALL.
17. Day 17: Data type conversions (CAST and CONVERT).
18. Day 18: Working with date and time functions.
19. Day 19: String manipulation functions.
20. Day 20: Error handling with TRY...CATCH.
21. Day 21: Practice complex queries and data manipulation tasks.
Week 4: Advanced Level
Day 22-28: Advanced Topics
22. Day 22: Working with Views.
23. Day 23: Stored Procedures and Functions.
24. Day 24: Triggers and transactions.
25. Day 25: Windows Function
Day 26-30: Real-World Projects
26. Day 26: SQL Project-1
27. Day 27: SQL Project-2
28. Day 28: SQL Project-3
29. Day 29: Practice questions set
30. Day 30: Final review and practice, explore advanced topics in depth, or work on a personal project.
Like for more
Hope it helps :)
Week 1: Beginner Level
Day 1-3: Introduction and Setup
1. Day 1: Introduction to SQL, its importance, and various database systems.
2. Day 2: Installing a SQL database (e.g., MySQL, PostgreSQL).
3. Day 3: Setting up a sample database and practicing basic commands.
Day 4-7: Basic SQL Queries
4. Day 4: SELECT statement, retrieving data from a single table.
5. Day 5: WHERE clause and filtering data.
6. Day 6: Sorting data with ORDER BY.
7. Day 7: Aggregating data with GROUP BY and using aggregate functions (COUNT, SUM, AVG).
Week 2-3: Intermediate Level
Day 8-14: Working with Multiple Tables
8. Day 8: Introduction to JOIN operations.
9. Day 9: INNER JOIN and LEFT JOIN.
10. Day 10: RIGHT JOIN and FULL JOIN.
11. Day 11: Subqueries and correlated subqueries.
12. Day 12: Creating and modifying tables with CREATE, ALTER, and DROP.
13. Day 13: INSERT, UPDATE, and DELETE statements.
14. Day 14: Understanding indexes and optimizing queries.
Day 15-21: Data Manipulation
15. Day 15: CASE statements for conditional logic.
16. Day 16: Using UNION and UNION ALL.
17. Day 17: Data type conversions (CAST and CONVERT).
18. Day 18: Working with date and time functions.
19. Day 19: String manipulation functions.
20. Day 20: Error handling with TRY...CATCH.
21. Day 21: Practice complex queries and data manipulation tasks.
Week 4: Advanced Level
Day 22-28: Advanced Topics
22. Day 22: Working with Views.
23. Day 23: Stored Procedures and Functions.
24. Day 24: Triggers and transactions.
25. Day 25: Windows Function
Day 26-30: Real-World Projects
26. Day 26: SQL Project-1
27. Day 27: SQL Project-2
28. Day 28: SQL Project-3
29. Day 29: Practice questions set
30. Day 30: Final review and practice, explore advanced topics in depth, or work on a personal project.
Like for more
Hope it helps :)
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If you are trying to transition into the data analytics domain and getting started with SQL, focus on the most useful concept that will help you solve the majority of the problems, and then try to learn the rest of the topics:
๐๐ป Basic Aggregation function:
1๏ธโฃ AVG
2๏ธโฃ COUNT
3๏ธโฃ SUM
4๏ธโฃ MIN
5๏ธโฃ MAX
๐๐ป JOINS
1๏ธโฃ Left
2๏ธโฃ Inner
3๏ธโฃ Self (Important, Practice questions on self join)
๐๐ป Windows Function (Important)
1๏ธโฃ Learn how partitioning works
2๏ธโฃ Learn the different use cases where Ranking/Numbering Functions are used? ( ROW_NUMBER,RANK, DENSE_RANK, NTILE)
3๏ธโฃ Use Cases of LEAD & LAG functions
4๏ธโฃ Use cases of Aggregate window functions
๐๐ป GROUP BY
๐๐ป WHERE vs HAVING
๐๐ป CASE STATEMENT
๐๐ป UNION vs Union ALL
๐๐ป LOGICAL OPERATORS
Other Commonly used functions:
๐๐ป IFNULL
๐๐ป COALESCE
๐๐ป ROUND
๐๐ป Working with Date Functions
1๏ธโฃ EXTRACTING YEAR/MONTH/WEEK/DAY
2๏ธโฃ Calculating date differences
๐๐ปCTE
๐๐ปViews & Triggers (optional)
Here is an amazing resources to learn & practice SQL: https://bit.ly/3FxxKPz
Share with credits: https://t.me/sqlspecialist
Hope it helps :)
๐๐ป Basic Aggregation function:
1๏ธโฃ AVG
2๏ธโฃ COUNT
3๏ธโฃ SUM
4๏ธโฃ MIN
5๏ธโฃ MAX
๐๐ป JOINS
1๏ธโฃ Left
2๏ธโฃ Inner
3๏ธโฃ Self (Important, Practice questions on self join)
๐๐ป Windows Function (Important)
1๏ธโฃ Learn how partitioning works
2๏ธโฃ Learn the different use cases where Ranking/Numbering Functions are used? ( ROW_NUMBER,RANK, DENSE_RANK, NTILE)
3๏ธโฃ Use Cases of LEAD & LAG functions
4๏ธโฃ Use cases of Aggregate window functions
๐๐ป GROUP BY
๐๐ป WHERE vs HAVING
๐๐ป CASE STATEMENT
๐๐ป UNION vs Union ALL
๐๐ป LOGICAL OPERATORS
Other Commonly used functions:
๐๐ป IFNULL
๐๐ป COALESCE
๐๐ป ROUND
๐๐ป Working with Date Functions
1๏ธโฃ EXTRACTING YEAR/MONTH/WEEK/DAY
2๏ธโฃ Calculating date differences
๐๐ปCTE
๐๐ปViews & Triggers (optional)
Here is an amazing resources to learn & practice SQL: https://bit.ly/3FxxKPz
Share with credits: https://t.me/sqlspecialist
Hope it helps :)
๐21โค7
๐๐๐ ๐๐๐ฌ๐ ๐๐ญ๐ฎ๐๐ข๐๐ฌ ๐๐จ๐ซ ๐๐ง๐ญ๐๐ซ๐ฏ๐ข๐๐ฐ:
Join for more: https://t.me/sqlanalyst
1. Dannyโs Diner:
Restaurant analytics to understand the customer orders pattern.
Link: https://8weeksqlchallenge.com/case-study-1/
2. Pizza Runner
Pizza shop analytics to optimize the efficiency of the operation
Link: https://8weeksqlchallenge.com/case-study-2/
3. Foodie Fie
Subscription-based food content platform
Link: https://lnkd.in/gzB39qAT
4. Data Bank: Thatโs money
Analytics based on customer activities with the digital bank
Link: https://lnkd.in/gH8pKPyv
5. Data Mart: Fresh is Best
Analytics on Online supermarket
Link: https://lnkd.in/gC5bkcDf
6. Clique Bait: Attention capturing
Analytics on the seafood industry
Link: https://lnkd.in/ggP4JiYG
7. Balanced Tree: Clothing Company
Analytics on the sales performance of clothing store
Link: https://8weeksqlchallenge.com/case-study-7
8. Fresh segments: Extract maximum value
Analytics on online advertising
Link: https://8weeksqlchallenge.com/case-study-8
Join for more: https://t.me/sqlanalyst
1. Dannyโs Diner:
Restaurant analytics to understand the customer orders pattern.
Link: https://8weeksqlchallenge.com/case-study-1/
2. Pizza Runner
Pizza shop analytics to optimize the efficiency of the operation
Link: https://8weeksqlchallenge.com/case-study-2/
3. Foodie Fie
Subscription-based food content platform
Link: https://lnkd.in/gzB39qAT
4. Data Bank: Thatโs money
Analytics based on customer activities with the digital bank
Link: https://lnkd.in/gH8pKPyv
5. Data Mart: Fresh is Best
Analytics on Online supermarket
Link: https://lnkd.in/gC5bkcDf
6. Clique Bait: Attention capturing
Analytics on the seafood industry
Link: https://lnkd.in/ggP4JiYG
7. Balanced Tree: Clothing Company
Analytics on the sales performance of clothing store
Link: https://8weeksqlchallenge.com/case-study-7
8. Fresh segments: Extract maximum value
Analytics on online advertising
Link: https://8weeksqlchallenge.com/case-study-8
๐21โค5
Best Way to Learn SQL in 2024
๐๐
https://www.linkedin.com/posts/sql-analysts_codecademy-sql-dataanalytics-activity-7177170950881218560-MdKt?utm_source=share&utm_medium=member_android
๐๐
https://www.linkedin.com/posts/sql-analysts_codecademy-sql-dataanalytics-activity-7177170950881218560-MdKt?utm_source=share&utm_medium=member_android
๐6
Complete Roadmap to learn SQL
๐๐
https://www.linkedin.com/posts/sql-analysts_complete-roadmap-to-learn-sql-in-2024-activity-7177533338776199169-_lH_?utm_source=share&utm_medium=member_android
๐๐
https://www.linkedin.com/posts/sql-analysts_complete-roadmap-to-learn-sql-in-2024-activity-7177533338776199169-_lH_?utm_source=share&utm_medium=member_android
๐6
Frequently asked SQL interview questions for Data Analyst/Data Engineer role-
1 - What is SQL and what are its main features?
2 - Order of writing SQL query?
3- Order of execution of SQL query?
4- What are some of the most common SQL commands?
5- Whatโs a primary key & foreign key?
6 - All types of joins and questions on their outputs?
7 - Explain all window functions and difference between them?
8 - What is stored procedure?
9 - Difference between stored procedure & Functions in SQL?
10 - What is trigger in SQL?
11 - Difference between where and having?
1 - What is SQL and what are its main features?
2 - Order of writing SQL query?
3- Order of execution of SQL query?
4- What are some of the most common SQL commands?
5- Whatโs a primary key & foreign key?
6 - All types of joins and questions on their outputs?
7 - Explain all window functions and difference between them?
8 - What is stored procedure?
9 - Difference between stored procedure & Functions in SQL?
10 - What is trigger in SQL?
11 - Difference between where and having?
๐29โค2
SQL Interview Questions with Answers ๐๐
https://www.linkedin.com/posts/sql-analysts_sql-interview-sqlinterview-activity-7178076668752760832-C2Fy?utm_source=share&utm_medium=member_android
https://www.linkedin.com/posts/sql-analysts_sql-interview-sqlinterview-activity-7178076668752760832-C2Fy?utm_source=share&utm_medium=member_android
๐3
Many people pay too much to learn SQL, but my mission is to break down barriers. I have shared complete learning series to learn SQL from scratch.
Here are the links to the SQL series
Complete SQL Topics for Data Analyst: https://t.me/sqlspecialist/523
Part-1: https://t.me/sqlspecialist/524
Part-2: https://t.me/sqlspecialist/525
Part-3: https://t.me/sqlspecialist/526
Part-4: https://t.me/sqlspecialist/527
Part-5: https://t.me/sqlspecialist/529
Part-6: https://t.me/sqlspecialist/534
Part-7: https://t.me/sqlspecialist/534
Part-8: https://t.me/sqlspecialist/536
Part-9: https://t.me/sqlspecialist/537
Part-10: https://t.me/sqlspecialist/539
Part-11: https://t.me/sqlspecialist/540
Part-12:
https://t.me/sqlspecialist/541
Part-13: https://t.me/sqlspecialist/542
Part-14: https://t.me/sqlspecialist/544
Part-15: https://t.me/sqlspecialist/545
Part-16: https://t.me/sqlspecialist/546
Part-17: https://t.me/sqlspecialist/549
Part-18: https://t.me/sqlspecialist/552
Part-19: https://t.me/sqlspecialist/555
Part-20: https://t.me/sqlspecialist/556
I saw a lot of big influencers copy pasting my content after removing the credits. It's absolutely fine for me as more people are getting free education because of my content.
But I will really appreciate if you share credits for the time and efforts I put in to create such valuable content. I hope you can understand.
Complete Python Topics for Data Analysts: https://t.me/sqlspecialist/548
Complete Excel Topics for Data Analysts: https://t.me/sqlspecialist/547
I'll continue with learning series on Python, Power BI, Excel & Tableau.
Thanks to all who support our channel and share the content with proper credits. You guys are really amazing.
Hope it helps :)
Here are the links to the SQL series
Complete SQL Topics for Data Analyst: https://t.me/sqlspecialist/523
Part-1: https://t.me/sqlspecialist/524
Part-2: https://t.me/sqlspecialist/525
Part-3: https://t.me/sqlspecialist/526
Part-4: https://t.me/sqlspecialist/527
Part-5: https://t.me/sqlspecialist/529
Part-6: https://t.me/sqlspecialist/534
Part-7: https://t.me/sqlspecialist/534
Part-8: https://t.me/sqlspecialist/536
Part-9: https://t.me/sqlspecialist/537
Part-10: https://t.me/sqlspecialist/539
Part-11: https://t.me/sqlspecialist/540
Part-12:
https://t.me/sqlspecialist/541
Part-13: https://t.me/sqlspecialist/542
Part-14: https://t.me/sqlspecialist/544
Part-15: https://t.me/sqlspecialist/545
Part-16: https://t.me/sqlspecialist/546
Part-17: https://t.me/sqlspecialist/549
Part-18: https://t.me/sqlspecialist/552
Part-19: https://t.me/sqlspecialist/555
Part-20: https://t.me/sqlspecialist/556
I saw a lot of big influencers copy pasting my content after removing the credits. It's absolutely fine for me as more people are getting free education because of my content.
But I will really appreciate if you share credits for the time and efforts I put in to create such valuable content. I hope you can understand.
Complete Python Topics for Data Analysts: https://t.me/sqlspecialist/548
Complete Excel Topics for Data Analysts: https://t.me/sqlspecialist/547
I'll continue with learning series on Python, Power BI, Excel & Tableau.
Thanks to all who support our channel and share the content with proper credits. You guys are really amazing.
Hope it helps :)
โค44๐31๐4๐คฃ2๐1๐1
๐8
I am planning to start a SQL Interview Preparation Series with 25+ practical questions. Like if interested ๐
๐157โค15๐6
SQL Programming Resources
I am planning to start a SQL Interview Preparation Series with 25+ practical questions. Like if interested ๐
Which platform in would be best to do so. As I am planning to share videos & images, which platform would work for you guys?
Anonymous Poll
35%
Linkedin
16%
Instagram
4%
Twitter
3%
Tiktok
42%
YouTube
๐20โค2๐1
Few ways to optimise SQL Queries ๐๐
Use Indexing: Properly indexing your database tables can significantly speed up query performance by allowing the database to quickly locate the rows needed for a query.
Optimize Joins: Minimize the number of joins and use appropriate join types (e.g., INNER JOIN, LEFT JOIN) to ensure efficient data retrieval.
Avoid SELECT * : Instead of selecting all columns using SELECT *, explicitly specify only the columns needed for the query to reduce unnecessary data transfer and processing overhead.
Use WHERE Clause Wisely: Filter rows early in the query using WHERE clause to reduce the dataset size before joining or aggregating data.
Avoid Subqueries: Whenever possible, rewrite subqueries as JOINs or use Common Table Expressions (CTEs) for better performance.
Limit the Use of DISTINCT: Minimize the use of DISTINCT as it requires sorting and duplicate removal, which can be resource-intensive for large datasets.
Optimize GROUP BY and ORDER BY: Use GROUP BY and ORDER BY clauses judiciously, and ensure that they are using indexed columns whenever possible to avoid unnecessary sorting.
Consider Partitioning: Partition large tables to distribute data across multiple nodes, which can improve query performance by reducing I/O operations.
Monitor Query Performance: Regularly monitor query performance using tools like query execution plans, database profiler, and performance monitoring tools to identify and address bottlenecks.
Hope it helps :)
Use Indexing: Properly indexing your database tables can significantly speed up query performance by allowing the database to quickly locate the rows needed for a query.
Optimize Joins: Minimize the number of joins and use appropriate join types (e.g., INNER JOIN, LEFT JOIN) to ensure efficient data retrieval.
Avoid SELECT * : Instead of selecting all columns using SELECT *, explicitly specify only the columns needed for the query to reduce unnecessary data transfer and processing overhead.
Use WHERE Clause Wisely: Filter rows early in the query using WHERE clause to reduce the dataset size before joining or aggregating data.
Avoid Subqueries: Whenever possible, rewrite subqueries as JOINs or use Common Table Expressions (CTEs) for better performance.
Limit the Use of DISTINCT: Minimize the use of DISTINCT as it requires sorting and duplicate removal, which can be resource-intensive for large datasets.
Optimize GROUP BY and ORDER BY: Use GROUP BY and ORDER BY clauses judiciously, and ensure that they are using indexed columns whenever possible to avoid unnecessary sorting.
Consider Partitioning: Partition large tables to distribute data across multiple nodes, which can improve query performance by reducing I/O operations.
Monitor Query Performance: Regularly monitor query performance using tools like query execution plans, database profiler, and performance monitoring tools to identify and address bottlenecks.
Hope it helps :)
๐15โค5๐1๐1
Here are some essential SQL tips for beginners ๐๐
โ Primary Key = Unique Key + Not Null constraint
โ To perform case insensitive search use UPPER() function ex. UPPER(customer_name) LIKE โA%Aโ
โ LIKE operator is for string data type
โ COUNT(*), COUNT(1), COUNT(0) all are same
โ All aggregate functions ignore the NULL values
โ Aggregate functions MIN, MAX, SUM, AVG, COUNT are for int data type whereas STRING_AGG is for string data type
โ For row level filtration use WHERE and aggregate level filtration use HAVING
โ UNION ALL will include duplicates where as UNION excludes duplicates
โ If the results will not have any duplicates, use UNION ALL instead of UNION
โ We have to alias the subquery if we are using the columns in the outer select query
โ Subqueries can be used as output with NOT IN condition.
โ CTEs look better than subqueries. Performance wise both are same.
โ When joining two tables , if one table has only one value then we can use 1=1 as a condition to join the tables. This will be considered as CROSS JOIN.
โ Window functions work at ROW level.
โ The difference between RANK() and DENSE_RANK() is that RANK() skips the rank if the values are the same.
โ EXISTS works on true/false conditions. If the query returns at least one value, the condition is TRUE. All the records corresponding to the conditions are returned.
Like for more ๐๐
โ Primary Key = Unique Key + Not Null constraint
โ To perform case insensitive search use UPPER() function ex. UPPER(customer_name) LIKE โA%Aโ
โ LIKE operator is for string data type
โ COUNT(*), COUNT(1), COUNT(0) all are same
โ All aggregate functions ignore the NULL values
โ Aggregate functions MIN, MAX, SUM, AVG, COUNT are for int data type whereas STRING_AGG is for string data type
โ For row level filtration use WHERE and aggregate level filtration use HAVING
โ UNION ALL will include duplicates where as UNION excludes duplicates
โ If the results will not have any duplicates, use UNION ALL instead of UNION
โ We have to alias the subquery if we are using the columns in the outer select query
โ Subqueries can be used as output with NOT IN condition.
โ CTEs look better than subqueries. Performance wise both are same.
โ When joining two tables , if one table has only one value then we can use 1=1 as a condition to join the tables. This will be considered as CROSS JOIN.
โ Window functions work at ROW level.
โ The difference between RANK() and DENSE_RANK() is that RANK() skips the rank if the values are the same.
โ EXISTS works on true/false conditions. If the query returns at least one value, the condition is TRUE. All the records corresponding to the conditions are returned.
Like for more ๐๐
๐31โค9๐1
Top 10 Websites to Practice SQL Skills ๐๐
https://www.instagram.com/reel/C5csFy9N5v6/?igsh=eGEwbjRnMWwyejNo
https://www.instagram.com/reel/C5csFy9N5v6/?igsh=eGEwbjRnMWwyejNo
โค2
SQL CHEAT SHEET๐ฉโ๐ป
Here is a quick cheat sheet of some of the most essential SQL commands:
SELECT - Retrieves data from a database
UPDATE - Updates existing data in a database
DELETE - Removes data from a database
INSERT - Adds data to a database
CREATE - Creates an object such as a database or table
ALTER - Modifies an existing object in a database
DROP -Deletes an entire table or database
ORDER BY - Sorts the selected data in an ascending or descending order
WHERE โ Condition used to filter a specific set of records from the database
GROUP BY - Groups a set of data by a common parameter
HAVING - Allows the use of aggregate functions within the query
JOIN - Joins two or more tables together to retrieve data
INDEX - Creates an index on a table, to speed up search times.
Here is a quick cheat sheet of some of the most essential SQL commands:
SELECT - Retrieves data from a database
UPDATE - Updates existing data in a database
DELETE - Removes data from a database
INSERT - Adds data to a database
CREATE - Creates an object such as a database or table
ALTER - Modifies an existing object in a database
DROP -Deletes an entire table or database
ORDER BY - Sorts the selected data in an ascending or descending order
WHERE โ Condition used to filter a specific set of records from the database
GROUP BY - Groups a set of data by a common parameter
HAVING - Allows the use of aggregate functions within the query
JOIN - Joins two or more tables together to retrieve data
INDEX - Creates an index on a table, to speed up search times.
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30 commonly asked questions in database management system (DBMS) interviews
๐๐
1. What is a DBMS?
2. Differentiate between DBMS and RDBMS.
3. What are the advantages and disadvantages of using a DBMS?
4. Explain the three levels of data abstraction in DBMS.
5. What is a database schema?
6. Define normalization and its importance in database design.
7. What are the different types of database models?
8. What is ACID (Atomicity, Consistency, Isolation, Durability) in DBMS?
9. What is a primary key, and why is it important?
10. Explain the concept of foreign keys.
11. Differentiate between a candidate key, primary key, and super key.
12. What is a transaction in a database?
13. Describe the differences between DELETE, TRUNCATE, and DROP commands.
14. What is a view in a database?
15. Explain indexing in databases.
16. What is a stored procedure?
17. What are the advantages of using stored procedures?
18. Describe the differences between clustered and non-clustered indexes.
19. What is a deadlock in DBMS?
20. How can you avoid deadlocks in a database?
21. What is data redundancy, and how can it be minimized?
22. What is a trigger in a database?
23. Describe the different types of joins in SQL.
24. What is a constraint in a database?
25. Explain the differences between a unique key and a primary key.
26. How does SQL differ from NoSQL databases?
27. What is the CAP theorem, and how does it relate to databases?
28. Explain the concept of data warehousing.
29. What are OLTP and OLAP, and how do they differ?
30. How would you approach database performance tuning and optimization?
๐๐
1. What is a DBMS?
2. Differentiate between DBMS and RDBMS.
3. What are the advantages and disadvantages of using a DBMS?
4. Explain the three levels of data abstraction in DBMS.
5. What is a database schema?
6. Define normalization and its importance in database design.
7. What are the different types of database models?
8. What is ACID (Atomicity, Consistency, Isolation, Durability) in DBMS?
9. What is a primary key, and why is it important?
10. Explain the concept of foreign keys.
11. Differentiate between a candidate key, primary key, and super key.
12. What is a transaction in a database?
13. Describe the differences between DELETE, TRUNCATE, and DROP commands.
14. What is a view in a database?
15. Explain indexing in databases.
16. What is a stored procedure?
17. What are the advantages of using stored procedures?
18. Describe the differences between clustered and non-clustered indexes.
19. What is a deadlock in DBMS?
20. How can you avoid deadlocks in a database?
21. What is data redundancy, and how can it be minimized?
22. What is a trigger in a database?
23. Describe the different types of joins in SQL.
24. What is a constraint in a database?
25. Explain the differences between a unique key and a primary key.
26. How does SQL differ from NoSQL databases?
27. What is the CAP theorem, and how does it relate to databases?
28. Explain the concept of data warehousing.
29. What are OLTP and OLAP, and how do they differ?
30. How would you approach database performance tuning and optimization?
๐20โค8
Database keys
Database keys are essential for organizing and managing data effectively. In this post, we'll explore ten key concepts that every IT professional should know.
1. ๐ ๐ฃ๐ฟ๐ถ๐บ๐ฎ๐ฟ๐ ๐๐ฒ๐
- A unique identifier for each record in a table.
- Cannot be null.
- Ensures that each row is unique.
2. ๐ ๐๐ผ๐ฟ๐ฒ๐ถ๐ด๐ป ๐๐ฒ๐
- A field in one table that refers to the Primary Key of another table.
- Establishes relationships between tables.
3. ๐งฉ ๐๐ผ๐บ๐ฝ๐ผ๐๐ถ๐๐ฒ ๐๐ฒ๐
- A combination of two or more columns that uniquely identifies each record.
- Useful when a single column can't uniquely identify a record.
4. ๐ช ๐ฆ๐๐ฝ๐ฒ๐ฟ ๐๐ฒ๐
- One or more columns that can uniquely identify a record.
- A Primary Key is a type of Super Key.
5. ๐ ๐๐ฎ๐ป๐ฑ๐ถ๐ฑ๐ฎ๐๐ฒ ๐๐ฒ๐
- A column or set of columns that could be the Primary Key.
- Must be unique.
6. ๐ ๐จ๐ป๐ถ๐พ๐๐ฒ ๐๐ฒ๐
- Ensures uniqueness for a column or column combination.
- Similar to Primary Key but allows one null value.
7. ๐ค ๐๐น๐๐ฒ๐ฟ๐ป๐ฎ๐๐ฒ ๐๐ฒ๐
- A Candidate Key that isn't the Primary Key.
- Another option for a unique identifier.
8. ๐ ๐ก๐ฎ๐๐๐ฟ๐ฎ๐น ๐๐ฒ๐
- A key that's a natural part of the data, like an email address.
9. ๐ญ ๐ฆ๐๐ฟ๐ฟ๐ผ๐ด๐ฎ๐๐ฒ ๐๐ฒ๐
- An artificial key created when no natural unique identifier exists.
10. ๐ ๐ฆ๐ฒ๐ฐ๐ผ๐ป๐ฑ๐ฎ๐ฟ๐ ๐๐ฒ๐
- Used for data retrieval, not identification.
- Helps create non-clustered indexes.
Database keys are essential for organizing and managing data effectively. In this post, we'll explore ten key concepts that every IT professional should know.
1. ๐ ๐ฃ๐ฟ๐ถ๐บ๐ฎ๐ฟ๐ ๐๐ฒ๐
- A unique identifier for each record in a table.
- Cannot be null.
- Ensures that each row is unique.
2. ๐ ๐๐ผ๐ฟ๐ฒ๐ถ๐ด๐ป ๐๐ฒ๐
- A field in one table that refers to the Primary Key of another table.
- Establishes relationships between tables.
3. ๐งฉ ๐๐ผ๐บ๐ฝ๐ผ๐๐ถ๐๐ฒ ๐๐ฒ๐
- A combination of two or more columns that uniquely identifies each record.
- Useful when a single column can't uniquely identify a record.
4. ๐ช ๐ฆ๐๐ฝ๐ฒ๐ฟ ๐๐ฒ๐
- One or more columns that can uniquely identify a record.
- A Primary Key is a type of Super Key.
5. ๐ ๐๐ฎ๐ป๐ฑ๐ถ๐ฑ๐ฎ๐๐ฒ ๐๐ฒ๐
- A column or set of columns that could be the Primary Key.
- Must be unique.
6. ๐ ๐จ๐ป๐ถ๐พ๐๐ฒ ๐๐ฒ๐
- Ensures uniqueness for a column or column combination.
- Similar to Primary Key but allows one null value.
7. ๐ค ๐๐น๐๐ฒ๐ฟ๐ป๐ฎ๐๐ฒ ๐๐ฒ๐
- A Candidate Key that isn't the Primary Key.
- Another option for a unique identifier.
8. ๐ ๐ก๐ฎ๐๐๐ฟ๐ฎ๐น ๐๐ฒ๐
- A key that's a natural part of the data, like an email address.
9. ๐ญ ๐ฆ๐๐ฟ๐ฟ๐ผ๐ด๐ฎ๐๐ฒ ๐๐ฒ๐
- An artificial key created when no natural unique identifier exists.
10. ๐ ๐ฆ๐ฒ๐ฐ๐ผ๐ป๐ฑ๐ฎ๐ฟ๐ ๐๐ฒ๐
- Used for data retrieval, not identification.
- Helps create non-clustered indexes.
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Top 20 SQL Interview Questions
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https://www.linkedin.com/posts/sql-analysts_here-is-the-list-of-top-20-sql-interview-activity-7188152088822988800-nuUU?utm_source=share&utm_medium=member_android
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