Commonly used aggregate functions in mysql

MySQL aggregate functions are used to perform calculations on groups of data and return a single value. Common functions include: SUM(): Sum COUNT(): Count of non-null values ​​AVG(): Average MIN(): Minimum value MAX(): Maximum value STDEV(): Standard deviation VARIANCE(): Variance GROUP_CONCAT( ): Connection string CORR(): Correlation coefficient REGEXP_REPLACE(): Regular expression replacement

Commonly used aggregate functions in MySQL

Aggregation functions are used to calculate a set of data and return a single value. There are a variety of aggregate functions available in MySQL that serve different purposes.

1. SUM():
Find the sum of a numeric column.

2. COUNT():
Count the number of non-null values ​​in the column.

3. AVG():
Calculate the average of a numeric column.

4. MIN():
Returns the minimum value in the numeric column.

5. MAX():
Returns the maximum value in the numeric column.

6. STDEV():
Calculate the standard deviation of a numeric column.

7. VARIANCE():
Calculate the variance of a numeric column.

8. GROUP_CONCAT():
Concatenate the values ​​in the specified column into a string.

9. CORR():
Calculate the correlation coefficient between two numeric columns.

10. REGEXP_REPLACE():
Use regular expressions to replace substrings in a string.

Usage:

Aggregation functions are often used with the GROUP BY clause to group data and then apply the aggregate function to each group. For example:

<code class="sql">SELECT department, SUM(salary)
FROM employee
GROUP BY department;</code>

This will sum employee salaries by department and return the total salary for each department.

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