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. 🗝 𝗣𝗿𝗶𝗺𝗮𝗿𝘆 𝗞𝗲𝘆
- A unique identifier for each record in a table.
- Cannot be null.
- Ensures that each row is unique.
2. 🌉 𝗙𝗼𝗿𝗲𝗶𝗴𝗻 𝗞𝗲𝘆
- A field in one table that refers to the Primary Key of another table.
- Establishes relationships between tables.
3. 🧩 𝗖𝗼𝗺𝗽𝗼𝘀𝗶𝘁𝗲 𝗞𝗲𝘆
- A combination of two or more columns that uniquely identifies each record.
- Useful when a single column can't uniquely identify a record.
4. 💪 𝗦𝘂𝗽𝗲𝗿 𝗞𝗲𝘆
- One or more columns that can uniquely identify a record.
- A Primary Key is a type of Super Key.
5. 🏅 𝗖𝗮𝗻𝗱𝗶𝗱𝗮𝘁𝗲 𝗞𝗲𝘆
- A column or set of columns that could be the Primary Key.
- Must be unique.
6. 🔍 𝗨𝗻𝗶𝗾𝘂𝗲 𝗞𝗲𝘆
- Ensures uniqueness for a column or column combination.
- Similar to Primary Key but allows one null value.
7. 🛤 𝗔𝗹𝘁𝗲𝗿𝗻𝗮𝘁𝗲 𝗞𝗲𝘆
- A Candidate Key that isn't the Primary Key.
- Another option for a unique identifier.
8. 🍃 𝗡𝗮𝘁𝘂𝗿𝗮𝗹 𝗞𝗲𝘆
- A key that's a natural part of the data, like an email address.
9. 🎭 𝗦𝘂𝗿𝗿𝗼𝗴𝗮𝘁𝗲 𝗞𝗲𝘆
- An artificial key created when no natural unique identifier exists.
10. 🔑 𝗦𝗲𝗰𝗼𝗻𝗱𝗮𝗿𝘆 𝗞𝗲𝘆
- 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. 🗝 𝗣𝗿𝗶𝗺𝗮𝗿𝘆 𝗞𝗲𝘆
- A unique identifier for each record in a table.
- Cannot be null.
- Ensures that each row is unique.
2. 🌉 𝗙𝗼𝗿𝗲𝗶𝗴𝗻 𝗞𝗲𝘆
- A field in one table that refers to the Primary Key of another table.
- Establishes relationships between tables.
3. 🧩 𝗖𝗼𝗺𝗽𝗼𝘀𝗶𝘁𝗲 𝗞𝗲𝘆
- A combination of two or more columns that uniquely identifies each record.
- Useful when a single column can't uniquely identify a record.
4. 💪 𝗦𝘂𝗽𝗲𝗿 𝗞𝗲𝘆
- One or more columns that can uniquely identify a record.
- A Primary Key is a type of Super Key.
5. 🏅 𝗖𝗮𝗻𝗱𝗶𝗱𝗮𝘁𝗲 𝗞𝗲𝘆
- A column or set of columns that could be the Primary Key.
- Must be unique.
6. 🔍 𝗨𝗻𝗶𝗾𝘂𝗲 𝗞𝗲𝘆
- Ensures uniqueness for a column or column combination.
- Similar to Primary Key but allows one null value.
7. 🛤 𝗔𝗹𝘁𝗲𝗿𝗻𝗮𝘁𝗲 𝗞𝗲𝘆
- A Candidate Key that isn't the Primary Key.
- Another option for a unique identifier.
8. 🍃 𝗡𝗮𝘁𝘂𝗿𝗮𝗹 𝗞𝗲𝘆
- A key that's a natural part of the data, like an email address.
9. 🎭 𝗦𝘂𝗿𝗿𝗼𝗴𝗮𝘁𝗲 𝗞𝗲𝘆
- An artificial key created when no natural unique identifier exists.
10. 🔑 𝗦𝗲𝗰𝗼𝗻𝗱𝗮𝗿𝘆 𝗞𝗲𝘆
- Used for data retrieval, not identification.
- Helps create non-clustered indexes.
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Basics of SQL 👇👇
1. SQL (Structured Query Language) is a standard programming language used for managing and manipulating relational databases.
2. SQL operates through simple, declarative statements. These statements are used to perform tasks such as querying data, updating data, inserting data, and deleting data from a database.
3. The basic SQL commands include SELECT, INSERT, UPDATE, DELETE, CREATE, and DROP.
4. The SELECT statement is used to retrieve data from a database. It allows you to specify the columns you want to retrieve and filter the results using conditions.
5. The INSERT statement is used to add new records to a table in a database.
6. The UPDATE statement is used to modify existing records in a table.
7. The DELETE statement is used to remove records from a table.
8. The CREATE statement is used to create new tables, indexes, or views in a database.
9. The DROP statement is used to remove tables, indexes, or views from a database.
10. SQL also supports various operators such as AND, OR, NOT, LIKE, IN, BETWEEN, and ORDER BY for filtering and sorting data.
11. SQL also allows for the use of functions and aggregate functions like SUM, AVG, COUNT, MIN, and MAX to perform calculations on data.
12. SQL statements are case-insensitive but conventionally written in uppercase for readability.
13. SQL databases are relational databases that store data in tables with rows and columns. Tables can be related to each other through primary and foreign keys.
14. SQL databases use transactions to ensure data integrity and consistency. Transactions can be committed (saved) or rolled back (undone) based on the success of the operations.
15. SQL databases support indexing for faster data retrieval and performance optimization.
16. SQL databases can be queried using tools like MySQL, PostgreSQL, Oracle Database, SQL Server, SQLite, and others.
Like if you need more similar content
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1. SQL (Structured Query Language) is a standard programming language used for managing and manipulating relational databases.
2. SQL operates through simple, declarative statements. These statements are used to perform tasks such as querying data, updating data, inserting data, and deleting data from a database.
3. The basic SQL commands include SELECT, INSERT, UPDATE, DELETE, CREATE, and DROP.
4. The SELECT statement is used to retrieve data from a database. It allows you to specify the columns you want to retrieve and filter the results using conditions.
5. The INSERT statement is used to add new records to a table in a database.
6. The UPDATE statement is used to modify existing records in a table.
7. The DELETE statement is used to remove records from a table.
8. The CREATE statement is used to create new tables, indexes, or views in a database.
9. The DROP statement is used to remove tables, indexes, or views from a database.
10. SQL also supports various operators such as AND, OR, NOT, LIKE, IN, BETWEEN, and ORDER BY for filtering and sorting data.
11. SQL also allows for the use of functions and aggregate functions like SUM, AVG, COUNT, MIN, and MAX to perform calculations on data.
12. SQL statements are case-insensitive but conventionally written in uppercase for readability.
13. SQL databases are relational databases that store data in tables with rows and columns. Tables can be related to each other through primary and foreign keys.
14. SQL databases use transactions to ensure data integrity and consistency. Transactions can be committed (saved) or rolled back (undone) based on the success of the operations.
15. SQL databases support indexing for faster data retrieval and performance optimization.
16. SQL databases can be queried using tools like MySQL, PostgreSQL, Oracle Database, SQL Server, SQLite, and others.
Like if you need more similar content
Hope it helps :)
❤31👍20🤣1
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:
👉🏻 Basic Aggregation function:
1️⃣ AVG
2️⃣ COUNT
3️⃣ SUM
4️⃣ MIN
5️⃣ MAX
👉🏻 JOINS
1️⃣ Left
2️⃣ Inner
3️⃣ Self (Important, Practice questions on self join)
👉🏻 Windows Function (Important)
1️⃣ Learn how partitioning works
2️⃣ Learn the different use cases where Ranking/Numbering Functions are used? ( ROW_NUMBER,RANK, DENSE_RANK, NTILE)
3️⃣ Use Cases of LEAD & LAG functions
4️⃣ Use cases of Aggregate window functions
👉🏻 GROUP BY
👉🏻 WHERE vs HAVING
👉🏻 CASE STATEMENT
👉🏻 UNION vs Union ALL
👉🏻 LOGICAL OPERATORS
Other Commonly used functions:
👉🏻 IFNULL
👉🏻 COALESCE
👉🏻 ROUND
👉🏻 Working with Date Functions
1️⃣ EXTRACTING YEAR/MONTH/WEEK/DAY
2️⃣ Calculating date differences
👉🏻CTE
👉🏻Views & Triggers (optional)
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 :)
👉🏻 Basic Aggregation function:
1️⃣ AVG
2️⃣ COUNT
3️⃣ SUM
4️⃣ MIN
5️⃣ MAX
👉🏻 JOINS
1️⃣ Left
2️⃣ Inner
3️⃣ Self (Important, Practice questions on self join)
👉🏻 Windows Function (Important)
1️⃣ Learn how partitioning works
2️⃣ Learn the different use cases where Ranking/Numbering Functions are used? ( ROW_NUMBER,RANK, DENSE_RANK, NTILE)
3️⃣ Use Cases of LEAD & LAG functions
4️⃣ Use cases of Aggregate window functions
👉🏻 GROUP BY
👉🏻 WHERE vs HAVING
👉🏻 CASE STATEMENT
👉🏻 UNION vs Union ALL
👉🏻 LOGICAL OPERATORS
Other Commonly used functions:
👉🏻 IFNULL
👉🏻 COALESCE
👉🏻 ROUND
👉🏻 Working with Date Functions
1️⃣ EXTRACTING YEAR/MONTH/WEEK/DAY
2️⃣ Calculating date differences
👉🏻CTE
👉🏻Views & Triggers (optional)
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 :)
👍26❤1
📊🚀A beginner's roadmap for learning SQL:
🔹Understand Basics:
Learn what SQL is and its purpose in managing relational databases.
Understand basic database concepts like tables, rows, columns, and relationships.
🔹Learn SQL Syntax:
Familiarize yourself with SQL syntax for common commands like SELECT, INSERT, UPDATE, DELETE.
Understand clauses like WHERE, ORDER BY, GROUP BY, and JOIN.
🔹Setup a Database:
Install a relational database management system (RDBMS) like MySQL, SQLite, or PostgreSQL.
Practice creating databases, tables, and inserting data.
🔹Retrieve Data (SELECT):
Learn to retrieve data from a database using SELECT statements.
Practice filtering data using WHERE clause and sorting using ORDER BY.
🔹Modify Data (INSERT, UPDATE, DELETE):
Understand how to insert new records, update existing ones, and delete data.
Be cautious with DELETE to avoid unintentional data loss.
🔹Working with Functions:
Explore SQL functions like COUNT, AVG, SUM, MAX, MIN for data analysis.
Understand string functions, date functions, and mathematical functions.
🔹Data Filtering and Sorting:
Learn advanced filtering techniques using AND, OR, and IN operators.
Practice sorting data using multiple columns.
🔹Table Relationships (JOIN):
Understand the concept of joining tables to retrieve data from multiple tables.
Learn about INNER JOIN, LEFT JOIN, RIGHT JOIN, and FULL JOIN.
🔹Grouping and Aggregation:
Explore GROUP BY clause to group data based on specific columns.
Understand aggregate functions for summarizing data (SUM, AVG, COUNT).
🔹Subqueries:
Learn to use subqueries to perform complex queries.
Understand how to use subqueries in SELECT, WHERE, and FROM clauses.
🔹Indexes and Optimization:
Gain knowledge about indexes and their role in optimizing queries.
Understand how to optimize SQL queries for better performance.
🔹Transactions and ACID Properties:
Learn about transactions and the ACID properties (Atomicity, Consistency, Isolation, Durability).
Understand how to use transactions to maintain data integrity.
🔹Normalization:
Understand the basics of database normalization to design efficient databases.
Learn about 1NF, 2NF, 3NF, and BCNF.
🔹Backup and Recovery:
Understand the importance of database backups.
Learn how to perform backups and recovery operations.
🔹Practice and Projects:
Apply your knowledge through hands-on projects.
Practice on platforms like LeetCode, HackerRank, or build your own small database-driven projects.
👀👍Remember to practice regularly and build real-world projects to reinforce your learning. Happy coding!
🔹Understand Basics:
Learn what SQL is and its purpose in managing relational databases.
Understand basic database concepts like tables, rows, columns, and relationships.
🔹Learn SQL Syntax:
Familiarize yourself with SQL syntax for common commands like SELECT, INSERT, UPDATE, DELETE.
Understand clauses like WHERE, ORDER BY, GROUP BY, and JOIN.
🔹Setup a Database:
Install a relational database management system (RDBMS) like MySQL, SQLite, or PostgreSQL.
Practice creating databases, tables, and inserting data.
🔹Retrieve Data (SELECT):
Learn to retrieve data from a database using SELECT statements.
Practice filtering data using WHERE clause and sorting using ORDER BY.
🔹Modify Data (INSERT, UPDATE, DELETE):
Understand how to insert new records, update existing ones, and delete data.
Be cautious with DELETE to avoid unintentional data loss.
🔹Working with Functions:
Explore SQL functions like COUNT, AVG, SUM, MAX, MIN for data analysis.
Understand string functions, date functions, and mathematical functions.
🔹Data Filtering and Sorting:
Learn advanced filtering techniques using AND, OR, and IN operators.
Practice sorting data using multiple columns.
🔹Table Relationships (JOIN):
Understand the concept of joining tables to retrieve data from multiple tables.
Learn about INNER JOIN, LEFT JOIN, RIGHT JOIN, and FULL JOIN.
🔹Grouping and Aggregation:
Explore GROUP BY clause to group data based on specific columns.
Understand aggregate functions for summarizing data (SUM, AVG, COUNT).
🔹Subqueries:
Learn to use subqueries to perform complex queries.
Understand how to use subqueries in SELECT, WHERE, and FROM clauses.
🔹Indexes and Optimization:
Gain knowledge about indexes and their role in optimizing queries.
Understand how to optimize SQL queries for better performance.
🔹Transactions and ACID Properties:
Learn about transactions and the ACID properties (Atomicity, Consistency, Isolation, Durability).
Understand how to use transactions to maintain data integrity.
🔹Normalization:
Understand the basics of database normalization to design efficient databases.
Learn about 1NF, 2NF, 3NF, and BCNF.
🔹Backup and Recovery:
Understand the importance of database backups.
Learn how to perform backups and recovery operations.
🔹Practice and Projects:
Apply your knowledge through hands-on projects.
Practice on platforms like LeetCode, HackerRank, or build your own small database-driven projects.
👀👍Remember to practice regularly and build real-world projects to reinforce your learning. Happy coding!
👍25❤7👏4
SQL Zero to Hero
👇👇
https://www.linkedin.com/posts/sql-analysts_many-people-pay-too-much-to-learn-sql-but-activity-7201219129310138368-2U6a
Like for more
👇👇
https://www.linkedin.com/posts/sql-analysts_many-people-pay-too-much-to-learn-sql-but-activity-7201219129310138368-2U6a
Like for more
👍12❤3
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:
👉🏻 Basic Aggregation function:
1️⃣ AVG
2️⃣ COUNT
3️⃣ SUM
4️⃣ MIN
5️⃣ MAX
👉🏻 JOINS
1️⃣ Left
2️⃣ Inner
3️⃣ Self (Important, Practice questions on self join)
👉🏻 Windows Function (Important)
1️⃣ Learn how partitioning works
2️⃣ Learn the different use cases where Ranking/Numbering Functions are used? ( ROW_NUMBER,RANK, DENSE_RANK, NTILE)
3️⃣ Use Cases of LEAD & LAG functions
4️⃣ Use cases of Aggregate window functions
👉🏻 GROUP BY
👉🏻 WHERE vs HAVING
👉🏻 CASE STATEMENT
👉🏻 UNION vs Union ALL
👉🏻 LOGICAL OPERATORS
Other Commonly used functions:
👉🏻 IFNULL
👉🏻 COALESCE
👉🏻 ROUND
👉🏻 Working with Date Functions
1️⃣ EXTRACTING YEAR/MONTH/WEEK/DAY
2️⃣ Calculating date differences
👉🏻CTE
👉🏻Views & Triggers (optional)
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 :)
👉🏻 Basic Aggregation function:
1️⃣ AVG
2️⃣ COUNT
3️⃣ SUM
4️⃣ MIN
5️⃣ MAX
👉🏻 JOINS
1️⃣ Left
2️⃣ Inner
3️⃣ Self (Important, Practice questions on self join)
👉🏻 Windows Function (Important)
1️⃣ Learn how partitioning works
2️⃣ Learn the different use cases where Ranking/Numbering Functions are used? ( ROW_NUMBER,RANK, DENSE_RANK, NTILE)
3️⃣ Use Cases of LEAD & LAG functions
4️⃣ Use cases of Aggregate window functions
👉🏻 GROUP BY
👉🏻 WHERE vs HAVING
👉🏻 CASE STATEMENT
👉🏻 UNION vs Union ALL
👉🏻 LOGICAL OPERATORS
Other Commonly used functions:
👉🏻 IFNULL
👉🏻 COALESCE
👉🏻 ROUND
👉🏻 Working with Date Functions
1️⃣ EXTRACTING YEAR/MONTH/WEEK/DAY
2️⃣ Calculating date differences
👉🏻CTE
👉🏻Views & Triggers (optional)
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 :)
👍17❤5😍2
Which of the following is a DDL command in SQL?
Anonymous Quiz
10%
NAME
75%
CREATE
9%
REMOVE
6%
RANK
👍13
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://news.1rj.ru/str/sqlspecialist/523
Part-1: https://news.1rj.ru/str/sqlspecialist/524
Part-2: https://news.1rj.ru/str/sqlspecialist/525
Part-3: https://news.1rj.ru/str/sqlspecialist/526
Part-4: https://news.1rj.ru/str/sqlspecialist/527
Part-5: https://news.1rj.ru/str/sqlspecialist/529
Part-6: https://news.1rj.ru/str/sqlspecialist/534
Part-7: https://news.1rj.ru/str/sqlspecialist/534
Part-8: https://news.1rj.ru/str/sqlspecialist/536
Part-9: https://news.1rj.ru/str/sqlspecialist/537
Part-10: https://news.1rj.ru/str/sqlspecialist/539
Part-11: https://news.1rj.ru/str/sqlspecialist/540
Part-12:
https://news.1rj.ru/str/sqlspecialist/541
Part-13: https://news.1rj.ru/str/sqlspecialist/542
Part-14: https://news.1rj.ru/str/sqlspecialist/544
Part-15: https://news.1rj.ru/str/sqlspecialist/545
Part-16: https://news.1rj.ru/str/sqlspecialist/546
Part-17: https://news.1rj.ru/str/sqlspecialist/549
Part-18: https://news.1rj.ru/str/sqlspecialist/552
Part-19: https://news.1rj.ru/str/sqlspecialist/555
Part-20: https://news.1rj.ru/str/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://news.1rj.ru/str/sqlspecialist/548
Complete Excel Topics for Data Analysts: https://news.1rj.ru/str/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://news.1rj.ru/str/sqlspecialist/523
Part-1: https://news.1rj.ru/str/sqlspecialist/524
Part-2: https://news.1rj.ru/str/sqlspecialist/525
Part-3: https://news.1rj.ru/str/sqlspecialist/526
Part-4: https://news.1rj.ru/str/sqlspecialist/527
Part-5: https://news.1rj.ru/str/sqlspecialist/529
Part-6: https://news.1rj.ru/str/sqlspecialist/534
Part-7: https://news.1rj.ru/str/sqlspecialist/534
Part-8: https://news.1rj.ru/str/sqlspecialist/536
Part-9: https://news.1rj.ru/str/sqlspecialist/537
Part-10: https://news.1rj.ru/str/sqlspecialist/539
Part-11: https://news.1rj.ru/str/sqlspecialist/540
Part-12:
https://news.1rj.ru/str/sqlspecialist/541
Part-13: https://news.1rj.ru/str/sqlspecialist/542
Part-14: https://news.1rj.ru/str/sqlspecialist/544
Part-15: https://news.1rj.ru/str/sqlspecialist/545
Part-16: https://news.1rj.ru/str/sqlspecialist/546
Part-17: https://news.1rj.ru/str/sqlspecialist/549
Part-18: https://news.1rj.ru/str/sqlspecialist/552
Part-19: https://news.1rj.ru/str/sqlspecialist/555
Part-20: https://news.1rj.ru/str/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://news.1rj.ru/str/sqlspecialist/548
Complete Excel Topics for Data Analysts: https://news.1rj.ru/str/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 :)
👍37❤25👏7😍2
Which of the following is not a window function in SQL?
Anonymous Poll
10%
RANK
18%
DENSE_RANK
14%
ROW_NUMBER
57%
RANGE
👍16