ms sql server equivalent of oracle’s NVL function
oracle’s NVL function:
a1 and a2 are expressions
return a2 if a1 is NULL
return a1 if a1 is not NULL
ms sql server equivlent is the ISNULL function:
a1 is checked for NULL
a2 is returned if a1 is NULL
return a1 if a1 is not null