• Aggregate functions are those functions that can be apply on multiple rows and returns signal result for all rows.
• They are also known as grouping functions.
• Oracle provides the following aggregate function.

### Sum()

• It return sum of all given values.
• Syntax
`` sum (val1, val2, …. Val n)``
• Example:
``SELECT sum ( 10, 20, 30 ) FROM DUAL ; ``
• Output:
`60`
• Example:
``SELECT sum ( salary ) FROM emp; ``
• Output:
`1,20,000`

### Max ()

• It returns maximum value from a given set of value.
• Syntax:
`max (val1, val2, ..., valN);`
• Example:
`SELECT max ( 10, 20, 30 ) FROM DUAL ;`
• Output:
`30`
• Example:
`SELECT max ( salary ) FROM emp ;`
• Output:
`20,000`

### Min ()

• It returns minimum value from a given set of value.
• Syntax:
`min (val1, val2, ..., valN);`
• Example:
`SELECT min( 10, 20, 30 ) FROM DUAL ;`
• Output:
`10`
• Example:
`SELECT min( salary ) FROM emp;`
• Output:
`5000`

### Avg ()

• It returns average value from a given set of value.
• Syntax:
`avg ( value1, value2, ..., valueN ) ;`
• Example:-
`SELECT avg ( 10, 20, 30 ) FROM DUAL; `
• Output:
`20`

### Count ()

• It returns total number of records of the database table.
• It has two form as follow.
• count (*):
• it count total no of records including duplicate records as well as null values.
• Syntax:
`count (*) ; `
• Example:
`SELECT count (*) FROM emp;`
• Output:
`35`
• count <expr>:
• it counts total number of records excluding null values.
• Syntax:
`count (expr) ;`
• Example:
`SELECT count (emp_no) FROM emp;`
• Output:
`30`