'scott' LIKE 'sc%t' intoarce TRUE
115 BETWEEN 110 AND 120 intoarce TRUE
'scott' IN ('mike', 'scott') intoarce TRUE, etc.

 mystring := ‘ ‘;        IF mystring = NULL THEN ….?
                               IF mystring != NULL THEN …?

 mynum := 0;           IF mynum = NULL THEN …?

 Mystring := ‘have fun’;
    Yourstring := NULL;      IF mystring != yourstring THEN …?

 IF NULL = NULL THEN …?

 IF NULL != NULL THEN …?