我们如何在 Oracle 中执行多个更新

Question

Table:T1 (key, numval, state) and T2(key, foreignkey:T1.key, type)

I have two tables T1 and T2, for each T1 there are multiple values in T2. And for each value in T2 there is a single value in T1.

Consider that I have two types ('A','B') in T2 and I have to count the number of T2s mapped to each T1 key with the state of 'A' and 'B'and set it to T1.state respectively

如何在 Oracle 中完成此操作？

类似下面的post（但是解法不行）： how to update a column in a table with unique values, but not all the rows, not incremented

使用上面的源 - 我使用了以下脚本：

UPDATE T1
SET VALUE =
   CASE
     WHEN (SELECT STATE FROM T1 WHERE KEY = EACH_KEY) = 'S1' 
                THEN 
                    (SELECT COUNT(*) FROM T2 
                                    WHERE KEY = EACH_KEY AND TYPE = 'A' 
     WHEN (SELECT STATE FROM T1 WHERE KEY = EACH_KEY) = 'S2' 
                THEN 
                    (SELECT COUNT(*) FROM T2 
                                    WHERE KEY = EACH_KEY AND TYPE = 'B' 
   END
WHERE  EACH_KEY in (select distinct KEY from T1);

但是 oracle 抛出以下错误：

Error at Command Line : 13 Column : 8
Error report -
SQL Error: ORA-00904: "EACH_KEY": invalid identifier
00904. 00000 -  "%s: invalid identifier"
*Cause:    
*Action:

编辑#1：

表格中的示例数据

执行前

T1
key    numval    state
1      0         S1
2      0         S2
3      0         S1
4      0         S1

T2
key    t1key     type
1      1         A
2      1         B
3      1         B
4      2         A
5      2         B
6      2         B
7      3         B
8      4         A
9      4         A
10      4         B

执行后（预期结果）

T1
key    numval    state
1      1         S1
2      2         S2
3      0         S1
4      2         S2

编辑#2：

是的，标识符未定义。我想知道如何在 Oracle SQL 中定义这样的标识符，以便可以执行上述计算。

Answer 1

UPDATE T1
SET numval = CASE WHEN t1.state = 'S1' THEN (SELECT COUNT(*) 
                                             FROM t2
                                             WHERE t1.key = t2.t1key
                                               AND type = 'A')
                  WHEN t1.state = 'S2' THEN (SELECT COUNT(*) 
                                             FROM t2
                                             WHERE t1.key = t2.t1key
                                               AND type = 'B')
             END

Answer 2

这是支持@jva 回答的测试用例：

用数据创建表：

create table t1 as
select 1 key, 0 numval, 'S1' state from dual union all
select 2 key, 0 numval, 'S2' state from dual union all
select 3 key, 0 numval, 'S1' state from dual union all
select 4 key, 0 numval, 'S1' state from dual;

create table t2 as
select 1 key, 1 t1key, 'A' type from dual union all
select 2 key, 1 t1key, 'B' type from dual union all
select 3 key, 1 t1key, 'B' type from dual union all
select 4 key, 2 t1key, 'A' type from dual union all
select 5 key, 2 t1key, 'B' type from dual union all
select 6 key, 2 t1key, 'B' type from dual union all
select 7 key, 3 t1key, 'B' type from dual union all
select 8 key, 4 t1key, 'A' type from dual union all
select 9 key, 4 t1key, 'A' type from dual union all
select 10 key, 4 t1key, 'B' type from dual;

检查t1中的初始值：

select * from t1 order by key;

       KEY     NUMVAL STATE
---------- ---------- -----
         1          0 S1   
         2          0 S2   
         3          0 S1   
         4          0 S1

执行更新：

update t1
set    numval = case when state = 'S1' then (select count(*) from t2 where t2.t1key = t1.key and t2.type = 'A')
                     when state = 'S2' then (select count(*) from t2 where t2.t1key = t1.key and t2.type = 'B')
                end;

commit;

检查 t1 中的新值：

select * from t1 order by key;

       KEY     NUMVAL STATE
---------- ---------- -----
         1          1 S1   
         2          2 S2   
         3          0 S1   
         4          2 S1

如您所见，这就是您想要的输出。

根据您在对@jva 的回答的评论中提到的"defects"，我认为您感到困惑：

在答案中使用相关子查询，并且
更新如何与相关子查询一起工作。

我强烈建议您查看 the documentation，特别是：

Oracle performs a correlated subquery when a nested subquery references a column from a table referred to a parent statement one level above the subquery. The parent statement can be a SELECT, UPDATE, or DELETE statement in which the subquery is nested. A correlated subquery conceptually is evaluated once for each row processed by the parent statement.

我们如何在 Oracle 中执行多个更新

How do we perform multiple updates in Oracle

oracle

oracle11g

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