conditional_where.sql

-- 4) Conditional where clause
SELECT 
  DAT.ID_VAR,
  DAT.SEQ_VAR,
  DAT.NUM_VAR,
  DATE_VAR1, 
  DATE_VAR2,
  TRUNC(DATE_VAR2) - TRUNC(DATE_VAR1) AS LAG_IN_DATES
FROM 
  CURRENT_TABLE      DAT 
WHERE
  (TRUNC(DATE_VAR2) - TRUNC(DATE_VAR1)) >= CASE WHEN SEQ_VAR IN (1,2,3) THEN 0 WHEN SEQ_VAR IN (4,5,6) THEN 1 ELSE 2 END 
ORDER BY ID_VAR, SEQ_VAR