What is COUNT function?

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What is COUNT function?

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COUNT is a group function that returns the number of rows returned by a query. The COUNT function has the following three formats:

  • COUNT (*): It returns the number of rows returned by a query, including duplicate rows and rows containing NULL values in any column.


  • COUNT (ALL ColumnName): It returns the number of rows containing non-NULL values in the column identified by ColumnName. It includes duplicate rows.


  • COUNT (DISTINCT ColumnName): It also returns the number of rows containing non-NULL values in the column identified by ColumnName. However, it excludes duplicate rows.


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