Task: Text to Code
Input (English): Step 1: find the StuID of Has_Pet table.
Step 2: find the Fname of Student table whose Student's StuID one of the results of step 1.
Step 3: find the Fname of Student table.
Step 4: show the rows that are in the results of step 2 but not in the results of step 3
Output (English): SELECT T1.Fname FROM Student AS T1 WHERE T1.StuID IN ( SELECT T2.StuID FROM Has_Pet AS T2 ) EXCEPT SELECT T1.Fname FROM Student AS T1