Microsoft SQL Server COUNT()


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


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).


Select COUNT(1) From Marksheet