Скачать или смотреть MySql Database | Count(), Sum() & Avg() in Aggregate function || Lecture No 21

Welcome to CodeCraze! In this video, we continue our journey through the MySQL tutorial for beginners with Lecture No 21, focusing on the powerful aggregate functions COUNT(), SUM(), and AVG(). These functions are essential tools for any developer working with databases, allowing you to perform calculations across multiple rows of data efficiently. Understanding these functions will enable you to summarize and analyze data more effectively, making your database queries more powerful and insightful.

In this lecture, we start by exploring the COUNT() function, which is used to count the number of rows that match a specified condition. Whether you're counting the number of customers in a database or the number of products in a particular category, COUNT() is an invaluable function for quickly retrieving such data. You'll see practical examples that demonstrate how to use COUNT() in different scenarios, including with GROUP BY to count rows grouped by a specific column.
Count():
Count(*): Returns the total number of records .i.e 6.
Count(salary): Return the number of Non-Null values over the column salary. i.e 5.
Count(Distinct Salary): Return the number of distinct Non-Null values over the column salary .i.e 5.

Next, we dive into the SUM() function, which calculates the total sum of a numeric column. This function is particularly useful in financial and statistical analyses, where summing up values like sales, revenue, or scores is a common task. We’ll go through various examples to show how SUM() can be used to add up data across multiple rows, and how you can apply conditions to get more specific results. You'll also learn how to combine SUM() with other SQL clauses to create more complex and insightful queries.
Sum():
sum(salary): Sum all Non-Null values of Column salary i.e., 3120.
sum(Distinct salary): Sum of all distinct Non-Null values i.e., 3120..

Finally, we cover the AVG() function, which calculates the average value of a numeric column. This function is frequently used in scenarios where you need to find the mean value of a set of data, such as the average salary of employees in a department or the average price of products in a store. We’ll explore different use cases, showing you how to use AVG() effectively in your queries. You’ll also see how AVG() can be combined with GROUP BY to find averages within specific groups of data.
Avg():
Avg(salary) = Sum(salary) / count(salary) = 3120 / 5 = 624
Avg(Distinct salary) = sum(Distinct salary) / Count(Distinct Salary) = 3120 / 5 = 624

Throughout the video, we focus on practical examples and real-world applications, ensuring that you can apply what you learn immediately to your own database projects. Whether you're working on a small project or managing large datasets, mastering these aggregate functions will enhance your ability to manipulate and analyze data with MySQL.

By the end of this lecture, you’ll have a solid understanding of how to use COUNT(), SUM(), and AVG() in your MySQL queries, and you’ll be equipped with the knowledge to handle more complex data analysis tasks. This video is a must-watch for anyone looking to deepen their MySQL skills and become more proficient in database management.

Make sure to check out the rest of the videos in our MySQL tutorial for beginners playlist for a comprehensive guide to mastering MySQL, from basic concepts to advanced techniques. Don’t forget to like, comment, and subscribe to CodeCraze for more programming tutorials and tips. We’re committed to helping you become a better programmer, one step at a time.

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