why should case statement be within select statement? : why should CASE statement be within SELECT statement? 

### Why does not the second code work? I mean, why should CASE statement be within SELECT statement? 

### First 
SELECT report_code,
       year,
       month,
       day,
       wind_speed,
   CASE 
       WHEN wind_speed >= 40 THEN 'HIGH' 
       WHEN wind_speed >= 30 AND wind_speed < 40 THEN 'MODERATE' 
       ELSE 'LOW' 
       END AS wind_severity
 
FROM station_data;

### Second 

SELECT report_code,
       year,
       month,
       day,
       wind_speed,
ROM station_data

CASE 
       WHEN wind_speed >= 40 THEN 'HIGH' 
       WHEN wind_speed >= 30 AND wind_speed < 40 THEN 'MODERATE' 
       ELSE 'LOW' 
       END AS wind_severity;