【 DB_Oracle】Oracle多表关联更新

table1 t1 set t1.c = ( select t2.c from table2 t2 where t1.a = t2.a) WHERE EXISTS ( SELECT 1 FROM table2 t2 WHERE t2.a = t1.a);

当在t1.a=t2.a的条件下t2查询出多条记录时也会报错，此时可以考虑将t2.c唯一化。

eg1:取满足条件的t2.c的最值

update table1 t1 set t1.c = (select max(t2.c) from table2  t2 where t1.a=t2.a) where exists(select 1 from table2 t2 where t2.a = t1.a);

eg2:取满足条件第一行的t2.c值

update table1 t1 set t1.c = (select t2.c  from table2  t2 where t1.a=t2.a  and rownum =1) where exists(select 1 from table2 t2 where t2.a = t1.a);

参考博文：ORACLE 两表关联更新三种方式

【 DB_Oracle】Oracle多表关联更新

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