@STRCMPNULL
Use the @STRCMPNULL in the same way as @STRCMP function to compare two character columns or literal strings, but if the arguments are NULL, the result value is 0 instead of NULL.
Syntax
@STRCMPNULL (<string1>, <string2>)
<string1>
The first column or literal string to be compared.
<string2>
The second column or literal string to be compared.