**Aggregate Functions**

**Aggregate Functions: **Aggregate functions perform a calculation on a set of rows and return a single row. You can use aggregate functions as expressions only in the following clauses i.e., SELECT clause, HAVING clause. There are five aggregate functions:

**AVG()** – returns the average value.**COUNT() **– returns the number of values.**MAX()** – returns the maximum value.**MIN()** – returns the minimum value.**SUM()** – returns the sum of all or distinct values.

**AVG(): **The AVG() function allows you to calculate the average value of a numeric column.

**syntax :** AVG(column)

SELECT AVG(SALARY) "AVERAGE SAL" FROM empl; |
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**Output : **

**COUNT(): **The COUNT function returns the total number of values in the specified field.

**syntax :** COUNT(expression)

SELECT COUNT(*) FROM empl; |
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**Output :**

**MAX() : **It returns the maximum value from the specified table field.

**syntax :** MAX(expression)

SELECT MAX(Salary) FROM empl; |
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**Output : **

**MIN(): **The MIN function returns the minimum value in the specified table field.

**syntax :** MIN(expression)

SELECT MIN(Salary)FROM empl; |
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**Output : **

**SUM():** SUM function which returns the sum of all the values in the specified column. SUM works on numeric fields only. Null values are excluded from the result returned.

**syntax :** SUM(expression)

SELECT SUM(Salary) "Total Salary" from empl; |
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**Output : **

These functions are called aggregate functions because they operate on the aggregate of tuples. The result of an aggregate function is a single value.

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