Returns sum of numeric values in a given column.

We have table as shown in figure that will be used to perform different aggregate functions. The table name is Marksheet.

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Select SUM(MarksObtained) From Marksheet

The sum function doesn't consider rows with NULL value in the field used as parameter

In the above example if we have another row like this:

106    Italian    NULL

This row will not be consider in sum calculation

Returns average of numeric values in a given column.

We have table as shown in figure that will be used to perform different aggregate functions. The table name is Marksheet.

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Select AVG(MarksObtained) From Marksheet

The average function doesn't consider rows with NULL value in the field used as parameter

In the above example if we have another row like this:

106    Italian    NULL

This row will not be consider in average calculation

Returns the largest value in a given column.

We have table as shown in figure that will be used to perform different aggregate functions. The table name is Marksheet.

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Select MAX(MarksObtained) From Marksheet

Returns the smallest value in a given column.

We have table as shown in figure that will be used to perform different aggregate functions. The table name is Marksheet.

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Select MIN(MarksObtained) From Marksheet

Returns the total number of values in a given column.

We have table as shown in figure that will be used to perform different aggregate functions. The table name is Marksheet.

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Select COUNT(MarksObtained) From Marksheet

The count function doesn't consider rows with NULL value in the field used as parameter. Usually the count parameter is * (all fields) so only if all fields of row are NULLs this row will not be considered

In the above example if we have another row like this:

106    Italian    NULL

This row will not be consider in count calculation

NOTE

The function COUNT(*) returns the number of rows in a table. This value can also be obtained by using a constant non-null expression that contains no column references, such as COUNT(1).

Example

Select COUNT(1) From Marksheet

Most of the time we like to get the total number of occurrence of a column value in a table for example:

TABLE NAME : REPORTS

SELECT  
    ReportName AS REPORT NAME, 
    COUNT(ReportName) AS COUNT 
FROM     
    REPORTS 
GROUP BY 
    ReportName 

Syntax

• AVG([ALL|DISTINCT]expression)
• COUNT([ALL|DISTINCT]expression)
• MAX([ALL|DISTINCT]expression)
• MIN([ALL|DISTINCT]expression)
• SUM([ALL|DISTINCT]expression)