SQL SERVER multiplication method

       SQL SERVER provides aggregate functions such as SUM, COUNT, MAX, MIN, AVG, etc., but does not provide the function of continuous multiplication, but in the actual development process, we may use the data of continuous multiplication, so we can realize the continuous multiplication by ourselves. Writing, test data:

--Test Data
if not object_id(N'Tempdb..#T') is null
	drop table #T
Go
Create table #T([num] int)
Insert #T
select 1 union all
select 2 union all
select 3 union all
select 4 union all
select 5
Go
-- end of test data

       Common implementation:

DECLARE @I BIGINT
SET @I = 1
SELECT  @I = @I * ISNULL([num], 1)
FROM    #T
SELECT  @I

       result:

       The above is the general way of writing, we can achieve the continuous multiplication form in a mathematical way:

SELECT  EXP(SUM(LOG(#T.num)))
FROM    #T

       The result is the same as above:

       Above we have realized the writing method of continuous multiplication.