sql - 从另一个表 Oracle 更新

Question

表格1

Tripid  sequence Pattern
  1       1       
  1       2
  1       3
  2       1   
  2       2 

表2

Tripid Pattern
  1      A
  2      B

我正在尝试更新表 1 的模式，最终结果应该是：

Tripid  sequence Pattern
  1       1        A
  1       2        A
  1       3        A
  2       1        B
  2       2        B

我使用的代码：

update table1
set table1.pattern = 
    (select pattern from table2 where table1.tripid = table2.tripid) 
where exists 
    (select pattern from table2 where table1.tripid = table2.tripid)

Oracle 数据库错误：ORA-01427：单行子查询返回多于一行

如何在 oracle 10g 中正确执行？

Answer 1

您可以为此使用MERGE语句。

查询：

select * from t1

结果：

| TRIPID | SEQ | PATTERN |
|--------|-----|---------|
|      1 |   1 |  (null) |
|      1 |   2 |  (null) |
|      1 |   3 |  (null) |
|      2 |   1 |  (null) |
|      2 |   2 |  (null) |

查询：

merge into t1
using t2
on (t1.tripid = t2.tripid)
when matched then update
set pattern = t2.pattern

查询：

select * from t1

结果：

| TRIPID | SEQ | PATTERN |
|--------|-----|---------|
|      1 |   1 |       A |
|      1 |   2 |       A |
|      1 |   3 |       A |
|      2 |   1 |       B |
|      2 |   2 |       B |

Answer 2

也许，tripid 在 table2 中不是唯一的？

它在您的示例中，但在您的真实数据中是独一无二的吗？

DROP  table table1;
create table table1(tripid number, sequence number, pattern  CHAR(1));
insert into table1 values (1,1,null);
insert into table1 values (1,2,null);
insert into table1 values (1,3,null);
insert into table1 values (2,1,null);
insert into table1 values (2,2,null);

DROP  table table2;
create table table2(tripid number, pattern CHAR(1));
insert into table2 values (1,'A');
insert into table2 values (2,'B');

commit;

select table2.tripid, table2.pattern from table2,table1 where table1.tripid = table2.tripid;


update table1
set table1.pattern = 
    (select pattern from table2 where table1.tripid = table2.tripid) 
where exists 
    (select pattern from table2 where table1.tripid = table2.tripid);

commit;

select * from table1;

返回：

Table dropped.
Table created.
1 row created.
1 row created.
1 row created.
1 row created.
1 row created.
Table dropped.
Table created.
1 row created.
1 row created.
Commit complete.

    TRIPID PATTERN
---------- -------
         1 A      
         1 A      
         1 A      
         2 B      
         2 B      

5 rows selected.
5 rows updated.


    TRIPID   SEQUENCE PATTERN
---------- ---------- -------
         1          1 A      
         1          2 A      
         1          3 A      
         2          1 B      
         2          2 B      

5 rows selected.

这证明有了良好的数据，Oracle（和您的查询）可以完美运行。

基督教