求助：请哪位牛人指点下，“统计查询出2017.6.1-2017.6.30(按出院日期)各病区科室的住院总人数、总天数、总费用“的查询语句怎么写？

Question

大概是三个表：
1，住院主记录表 PAT_VISIT   内有字段： 出院科室DEPT_DISCHARGE_FROM        入院科室DEPT_ADMISSION_TO
                                                                          出院日期 DISCHARGE_DATE_TIME          入院日期及时间ADMISSION_DATE_TIME
                                                                          总费用   TOTAL_COSTS     病人标识 PATIENT_ID   入账费用TOTAL_PAYMENTS
                                                                          病人本次住院标识 VISIT_ID2，住院病人费用表MEDICAL_COSTS  有字段：病人标识PATIENT_ID      费用分类FEE_TYPE     费用COSTS
                                                                                      病人本次住院标识 VISIT_ID     3，病人在科记录  TRANSFER                字段有：病人标识PATIENT_ID     病人本次住院标识 VISIT_ID    所在科室DEPT_STAYED
                                                                                      入科日期及时间ADMISSION_DATE_TIME
                                                                                      出科日期及时间DISCHARGE_DATE_TIME统计查询出2017.6.1-2017.6.30(按出院日期)各病区科室的住院总人数、总天数、总费用
 
     

Answer 1

为什么要从三张表中取数据，总记录表中数据不是很全吗？
select  
count(distinct PATIENT_ID ) as 住院总人数,
sum(DISCHARGE_DATE_TIME-ADMISSION_DATE_TIME) as 总天数,
sum(TOTAL_PAYMENTS) as 总费用
from PAT_VISIT
where DISCHARGE_DATE_TIME between date'2017-06-01' and '2017-06-30';