What are the five types of aggregate functions?

The five aggregate functions are: 1. SUM() function; 2. AVG() function; 3. MIN() function; 4. MAX() function; 5. COUNT() function. Aggregation functions, also known as combination functions or population functions, are mainly used to perform calculations on a set of values ​​and return a single value. These functions have different names and usage in different database systems, so you need to pay attention to the documentation and syntax regulations of the specific database when using them.

Aggregation functions are also called combination functions or population functions. They are mainly used to perform calculations on a set of values ​​and return a single value. The following are five common aggregate functions:

1. SUM():

• Function: Calculate the sum of a column.
• Syntax: SUM(column_name)
• Example: SELECT SUM(salary) FROM employees;

2, AVG():

• Function: Calculate the average of a certain column.
• Syntax: AVG(column_name)
• Example: SELECT AVG(salary) FROM employees;

3, MIN():

• Function: Return the minimum value of a certain column.
• Syntax: MIN(column_name)
• Example: SELECT MIN(salary) FROM employees;

4, MAX():

• Function: Return the maximum value of a column.
• Syntax: MAX(column_name)
• Example: SELECT MAX(salary) FROM employees;

5, COUNT():

• Function: Count the number of rows in a column.
• Syntax: COUNT(column_name)
• Example: SELECT COUNT(employee_id) FROM employees;

In addition to the above five aggregation functions, there are other aggregations Functions such as GROUP_CONCAT() (used in MySQL to concatenate multiple string values), STD() (calculate standard deviation), VAR_POP() and VAR_SAMP() (calculate population and sample variance respectively), etc. These functions have different names and usage in different database systems, so you need to pay attention to the documentation and syntax regulations of the specific database when using them.

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