SQL provides various aggregate functions which can summarize data of given table.

1.COUNT()

• This function is used to calculate number of rows in a table selected by query.

• COUNT returns the number of rows in the table when the column value is not NULL.

Example: Find total number of students

SELECT COUNT(Sid) as COUNT

FROM Exam_Marks

2.SUM()

•This function is used to calculate sum of column values in a table selected by query.

Example:

Find total of marks scored by all students

SELECT SUM(Marks) as SUM

FROM Exam_Marks

3.AVG()

• This function is used to calculate the average of column values in a table selected by query.

• This function first calculates sum of columns and then divide by total number of rows.

Example:

Find average marks of students

SELECT AVG(Marks) as AVG

FROM Exam_Marks

4.MIN()

•This function is used to find maximum value out of column values in a table selected by query.

Example:

Find total of marks scored by all students

SELECT MIN(Marks) as MIN

FROM Exam_Marks

5.MAX()

•This function is used to find maximum value out of column values in a table selected by query.

Example:

Find total of marks scored by all students

SELECT MAX(Marks) as MAX

FROM Exam_Marks