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COUNT 

COUNT is a set function.

·        COUNT(*) supplies the total number of values (rows in a result table or group).

·        COUNT(DISTINCT <expression>)supplies the total number of different values (number of values in the argument of the DISTINCT function).

·        COUNT(ALL <expression>)supplies the number of values that differ from the NULL value (number of values in the argument of the ALL function)

The result has the data type FIXED(10).

Example table: customer

How many customers are there?

SELECT COUNT (*) number FROM customer

number

15

 

 

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