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Writing a function to counts the number of primes in the range [1-N].

Hi everyone,
How can I write a function that counts the number of primes in the range [1-N].
(A natural number is called a prime, a prime number or just prime if it has exactly two distinct divisors. Therefore, 1 is not prime number, since it has only one divisor, namely 1.)

Pawan Kumar

Try this

--

DECLARE @StartRange AS INT = 2
DECLARE @EndRange AS INT = 50

SELECT COUNT (DISTINCT Number) PrimeNumbers
FROM
    MASTER..SPT_VALUES num
WHERE
    Number >= @StartRange AND Number <= @EndRange AND
        NOT EXISTS 
( 
        SELECT 1 FROM MASTER..SPT_VALUES AS num1 WHERE num1.Number > 1
    AND  num1.Number < num.Number
    AND  num.Number % num1.Number = 0
)

--

Open in new window

if you list of primes use below

--

DECLARE @StartRange AS INT = 2
DECLARE @EndRange AS INT = 50

SELECT DISTINCT Number PrimeNumbers
FROM
    MASTER..SPT_VALUES num
WHERE
    Number >= @StartRange AND Number <= @EndRange AND
        NOT EXISTS 
( 
        SELECT 1 FROM MASTER..SPT_VALUES AS num1 WHERE num1.Number > 1
    AND  num1.Number < num.Number
    AND  num.Number % num1.Number = 0
)

--

Open in new window

Output
------------------------
PrimeNumbers
-------------------------
2
3
5
7
11
13
17
19
23
29
31
37
41
43
47

ASKER CERTIFIED SOLUTION

Pawan Kumar

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Pawan Kumar

Hi BehrangDBA,
Did you get a chance to check this?

Regards,
Pawan

BehrangDBA

ASKER

Thank you very much for your time Pawan.