根据表2中的标准更新表1中的字段？ ORACLE

Question

我正努力制作适用于以下数据的更新脚本：

TOWER_PAYMENT TABLE                                         
============================================================== 
PAY_PERIOD|TOWER_ID|APARTMENT_NUM|MONTH_PAYMENT|PAYMENT_STATUS     
201703    |10      |101          |700          |NULL
201704    |10      |101          |700          |NULL
201703    |10      |102          |700          |NULL
201704    |10      |102          |700          |NULL                  
201703    |20      |101          |800          |NULL     
201704    |20      |101          |800          |NULL               
201703    |20      |102          |800          |NULL     
201704    |20      |102          |800          |NULL              

PAYMENT_STATUS TABLE
==============================================
PAY_PERIOD|TOWER_ID|APARTMENT_NUM|PAYMENT_DONE
201703    |10      |101          |700 
201704    |10      |101          |400 
201703    |10      |102          |500
201704    |10      |102          |700 
201703    |20      |101          |800 

我希望更新＆＃34; PAYMENT_STATUS＆＃34;具有基于不同标准的数字的字段：

• 如果是＆＃34; APARTMENT_NUM＆＃34;属于＆＃34; TOWER_ID＆＃34;可以在＆＃34; PAYMENT_STATUS＆＃34;用于匹配＆＃34; PAY_PERIOD＆＃34;的表格，然后更新＆＃34; PAYMENT_STATUS＆＃34;字段为1。
• 如果＆＃34; APARTMENT_NUM＆＃34;属于＆＃34; TOWER_ID的＆＃34; PAYMENT_STATUS＆＃34;用于匹配＆＃34; PAY_PERIOD＆＃34;的表格，然后更新＆＃34; PAYMENT_STATUS＆＃34;字段为2.
• 如果＆＃34; APARTMENT_NUM＆＃34;有一个＆＃34; PAYMENT_DONE＆＃34;小于＆＃34; MONTH_PAYMENT＆＃34;，然后更新＆＃34; PAYMENT_STATUS＆＃34;字段为3.

所需的输出应为：

TOWER_PAYMENT
====================================================================     
PAY_PERIOD|TOWER_ID|APARTMENT_NUM|MONTH_PAYMENT|PAYMENT_STATUS     
201703    |10      |101          |700          |1
201704    |10      |101          |700          |3
201703    |10      |102          |700          |3
201704    |10      |102          |700          |1                  
201703    |20      |101          |800          |1     
201704    |20      |101          |800          |2               
201703    |20      |102          |800          |2     
201704    |20      |102          |800          |2            

我已尝试使用MERGE INTO，但在不匹配时无法更新。

提前致谢！

Answer 1

UPDATE tower_payment
   SET payment_status   = CASE
                              WHEN (SELECT payment_done
                                      FROM payment_status
                                     WHERE tower_payment.apartment_num = payment_status.apartment_num) < month_payment
                              THEN
                                  3
                              WHEN (SELECT payment_done
                                      FROM payment_status
                                     WHERE tower_payment.apartment_num = payment_status.apartment_num)
                                       IS NULL
                              THEN
                                  2
                              ELSE
                                  1
                          END;