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MySQL Database Tutorial - 18 - More on Aggregate Functions Video Lecture | MySQL (Sequential Query Language) Database Tutorial - Software Development

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FAQs on MySQL Database Tutorial - 18 - More on Aggregate Functions Video Lecture - MySQL (Sequential Query Language) Database Tutorial - Software Development

1. What are aggregate functions in MySQL?
Ans. Aggregate functions in MySQL are used to perform calculations on a set of values and return a single value as a result. These functions include SUM, AVG, COUNT, MIN, and MAX. They are commonly used in SQL queries to obtain summary information from a database table.
2. How does the SUM function work in MySQL?
Ans. The SUM function in MySQL calculates the total sum of a column or a set of values. It takes a column or expression as an argument and returns the sum of all the values in that column. For example, "SELECT SUM(sales) FROM transactions" will return the total sales amount from the "transactions" table.
3. What is the difference between COUNT(*) and COUNT(column_name) in MySQL?
Ans. In MySQL, COUNT(*) and COUNT(column_name) are two different ways to use the COUNT function. COUNT(*) counts the number of rows in a table, regardless of whether any columns have NULL values. COUNT(column_name) counts the number of rows where the specified column has a non-NULL value. So, COUNT(*) will give the total number of rows in a table, while COUNT(column_name) will give the number of rows with non-NULL values in the specified column.
4. Can aggregate functions be used with GROUP BY in MySQL?
Ans. Yes, aggregate functions can be used with the GROUP BY clause in MySQL. When using GROUP BY, the result set is divided into groups based on the specified column(s). Aggregate functions can then be applied to each group separately, returning a result for each group. This is commonly used to calculate summary information for different groups in a table.
5. How can I find the maximum value in a column using MAX function in MySQL?
Ans. To find the maximum value in a column using the MAX function in MySQL, you can use the following syntax: "SELECT MAX(column_name) FROM table_name". This will return the highest value found in the specified column from the specified table. For example, "SELECT MAX(price) FROM products" will return the maximum price value from the "products" table.
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