从两列创建过程和更新

Question

我有两个表A和B，我不会从A更新D，如果C来自B，A = C，如果LB减去LA＆gt; = 2小时设置D = 0

Answer 1

MERGE可能是您的选择之一：

SQL> create table a (c number, d number, la date);

Table created.

SQL> create table b (c number, lb date);

Table created.

SQL> insert into a
  2    (select 12345, 30, to_date('01.04.2018 20:10', 'dd.mm.yyyy hh24:mi') from dual);

1 row created.

SQL> insert into b
  2    (select 12345, to_date('01.04.2018 18:00', 'dd.mm.yyyy hh24:mi') from dual);

1 row created.

SQL>
SQL> merge into a
  2    using (select b.c, b.lb from b) x
  3    on (a.c = x.c and
  4        (a.la - x.lb) * 24 >= 2
  5       )
  6  when matched then
  7    update set a.d = 0;

1 row merged.

SQL>
SQL> select * From a;

         C          D LA
---------- ---------- ----------
     12345          0 01.04.2018

阻止UPDATE的值：

SQL> delete from a;

1 row deleted.

SQL> insert into a
  2    (select 12345, 30, to_date('01.04.2018 19:10', 'dd.mm.yyyy hh24:mi') from dual);

1 row created.

SQL> merge into a
  2    using (select b.c, b.lb from b) x
  3    on (a.c = x.c and
  4        (a.la - x.lb) * 24 >= 2
  5       )
  6  when matched then
  7    update set a.d = 0;

0 rows merged.

SQL> select * From a;

         C          D LA
---------- ---------- ----------
     12345         30 01.04.2018

SQL>