Aggregate functions in SQL

 Aggregate functions:

Ø Aggregate functions are used to perform calculations on a data set to get the single value from the user defined data.

Uses of Aggregate functions:

Ø It performs arithmetic operation as well as calculation on set values and returns a single value.

Ø Aggregate functions used with the group by clause of the select statement.

Ø Aggregate functions ignores all null values (Except Count(*).

What are Aggregate functions?

1.    Max()

2.    Min()

3.    Avg()

4.    Count()

5.    Sum()

Max():

 Max() function used to find the largest value in the selected column.

Syntax:

1. Select Max (column_name)

   From table_name;

Example:

1. Select Max (sal)

   From emp;

Min():

 Max() function used to find the largest value in the selected column.

Syntax:

1. Select Min (column_name)

   From table_name;

Example:

1. Select Min (sal)

   From emp;

Avg():

Avg() function is used to return the average value of the numeric column.

Syntax:

1. Select Avg (column_name)

   From table_name;

Example:

1. Select Avg (Price)

   From Book;

Sum():

Sum() function is used to return average value of the numeric column.

Syntax:

1. Select  Sum (column_name)

   From table_name;

Example:

1. Select Sum (sal+comm)

   From emp;

Example:2

1. Select Sum (sal)

   From emp
2. where deptno=10;

Count():

Count() function is used to return the number of rows or records in the table.

Syntax:

1. Select Count (column_name)

   From table_name;

Example:1

1. Select Count (*)

   From emp;

Example:2

1. Select Count (Emp_name)

   From emp;

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