I am trying to subtract 2 dates from each other but it seems that it is not subtracting properly and i am not sure what i am doing wrong here. I am using case statement to flag as 1 if the difference between the dates are less than 90 days else flag it as 0. But it is always flagging as 1 even if the difference between the dates are greater than 90 days. I am PostgreSQL here and here is my case statement:

```
CASE WHEN EXTRACT(DAY FROM CAST(SVS_DT AS DATE) - CAST(DSCH_TS AS DATE)) <90 
      THEN 1 ELSE 0 END AS FU90

```

example of the dates are here:

```
SVS_DT                         DSCH_TS
2013-03-22 00:00:00            2010-05-06 00:00:00

```

it is suppose to flag as 0 in this case but it is flagging as 1 because the difference between these 2 dates are greater than 90 days.