What are the aggregate functions in mysql

MySQL aggregate functions are used to summarize data in a dataset. Common functions include SUM(), COUNT(), AVG(), MIN(), and MAX(). It is used through the SELECT query statement, and the format is SELECT aggregate function (column name) FROM table name. For grouped aggregation, you can use the GROUP BY clause to group the data and then perform the aggregation operation on each group.

Aggregation functions in MySQL

Aggregation functions are used for summary by combining a set of values ​​into a single value Or aggregate data from a dataset. MySQL provides a variety of aggregate functions to handle various aggregation operations.

Common aggregate functions:

• SUM(): Calculate the sum of a set of values.
• COUNT(): Count the number of values ​​in a set of values.
• AVG(): Calculate the average of a set of values.
• MIN(): Returns the minimum value in a set of values.
• MAX(): Returns the maximum value in a set of values.
• GROUP_CONCAT(): Concatenate a group of strings into one string.

Other aggregate functions:

In addition to the above common functions, MySQL also provides some other aggregate functions:

• STDDEV(): Calculate the standard deviation of a set of values.
• VARIANCE(): Calculate the variance of a set of values.
• BIT_OR(): Performs a bitwise OR operation between a set of bit values.
• BIT_XOR(): Performs a bitwise XOR operation between a set of bit values.

Function usage:

Aggregation functions are used in SELECT query statements, the format is:

<code>SELECT 聚合函数(列名)
FROM 表名
[WHERE 条件]
[GROUP BY 分组列]</code>

For example, to calculate " sales" column sum:

<code>SELECT SUM(sales)
FROM sales_table</code>

Group aggregation:

The GROUP BY clause can be used to group data based on one or more columns and then perform Aggregation operations. For example, to calculate the average of the "sales" column in each product category:

<code>SELECT product_category, AVG(sales)
FROM sales_table
GROUP BY product_category</code>

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