Convert decimal to binary

Create Function DBO. f_dec_bin (@ num bigint, @ length INT)
Returns varchar (64)
As
Begin
-- Author: pbsql
-- @ Num is the positive integer to be converted to a binary string. If it is a negative number, '0' is returned'
-- @ Length indicates the length of the binary string to be returned.
-- If @ length is negative, '0' is returned. If it is 0, the actual length of the binary string is returned.
-- If @ length is greater than 0, the return value is a binary string with the length of @ length (from the low position, the bits are not high enough to fill in '0', and the bits are truncated when the bits exceed the bits)
Declare @ result varchar (64)
Set @ result =''
If @ num <= 0 or @ length <0
Set @ result = '0'
Else
Begin
While @ num <> 0
Select @ result = cast (@ num % 2 as varchar) + @ result, @ num = @ num/2
If @ length> 0
Set @ result = right (replicate ('0', @ length) + @ result, @ length)
End
Return @ result
End
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