用查询中的值替换字段的一部分 [英] Replace part of field with values from query

问题描述

我有一个字段，其中填充了一系列特定格式的条件:

I have a field that is populated with a series of criteria in a specific format:

CRITERIA
$1 = True
$2 > $3

标准信息存储在表中

CRIT_ID CRIT_DESCRIPTION
1       Example 1
2       Example 2
3       Example 3

最终输出应如下所示

CRITERIA
Example 1 = True
Example 2 > Example 3

有人可以建议如何最好地做到这一点吗?到目前为止，我已经尝试过REPLACE并涉足REGEXP_REPLACE ...

Can anyone suggest how best to accomplish this? I have tried REPLACE and dabbled with REGEXP_REPLACE so far...

推荐答案

也许不是最有效的方法，但它是递归工作的(也就是说，如果crit_description本身包含占位符"，那么它们也会被扩展.(A第一个解决方案比下面显示的简单，没有执行此递归步骤.)请参阅我添加的第三个示例输入.如果可以进行更多清理，我将在稍后再次发布.

Perhaps not the most efficient, but it works recursively (that is, if the crit_description itself contains "placeholders", those are expanded as well. (A first solution, simpler than what's shown below, didn't do this recursive step.) See the third sample input which I added. I will post again later if I can clean it up some more.

注意:这假定在criteria_info表中实际找到了所有占位符"；我没有测试如果找不到它们会发生什么. OP陈述要求.

NOTE: This assumes all "placeholders" are actually found in the criteria_info table; I didn't test what happens if they are not found. OP to state the requirement.

with
     inputs ( criteria ) as (
       select '$1 = True' from dual union all
       select '$2 > $3'   from dual union all
       select '$1 = $4'   from dual
     ),
     criteria_info ( crit_id, crit_description ) as (
       select 1, 'Example 1' from dual union all
       select 2, 'Example 2' from dual union all
       select 3, 'Example 3' from dual union all
       select 4, '$2 + $3'   from dual
     ),
     rec ( criteria, new_str ) as (
       select  criteria, criteria
         from  inputs        
       union all       
       select  r.criteria, 
               regexp_replace(r.new_str, '\$\d+', c.crit_description, 1, 1)
         from  rec r inner join criteria_info c
               on to_number(regexp_substr(r.new_str, '\$(\d+)', 1, 1, null, 1)) = c.crit_id
         where regexp_substr(r.new_str, '\$\d+') is not null
     )
select criteria, new_str
from   rec
where  regexp_substr(new_str, '\$\d+') is null
;


CRITERIA  NEW_STR
--------- ------------------------------------
$1 = True Example 1 = True
$2 > $3   Example 2 > Example 3
$1 = $4   Example 1 = Example 2 + Example 3

3 rows selected.

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