您可以在 postgresql 存储过程中的插入语句中的临时行上引用聚合函数吗？

Question

我正在编写一个 postgres 存储过程，它循环遍历从 select 语句返回的行。对于它循环的每一行，它将 select 语句中的值插入到新的 table 中。我需要插入第二个 table 的值之一是一列的平均值。但是，当我调用存储过程时，我得到一个错误，即临时行没有我正在平均的实际列的属性。请参阅下面的存储过程和错误。

存储过程：

create or replace procedure sendToDataset(sentence int)
as $$
declare temprow peoplereviews%rowtype;
BEGIN

  FOR temprow IN
      select rulereviewid, avg(rulereview)
      from peoplereviews 
      where sentenceid = sentence
      group by rulereviewid
  loop
      insert into TrainingDataSet(sentenceId, sentence, ruleCorrectId, ruleCorrect, dateAdded)
          values(sentence, getSentenceFromID(sentence), tempRow.rulereviewid, tempRow.avg(rulereview), current_timestamp);
    END LOOP;

END
$$ 
LANGUAGE plpgsql;

错误：

ERROR:  column "rulereview" does not exist
LINE 2: ...omID(sentence), tempRow.rulereviewid, tempRow.avg(rulereview...
                                                             ^
QUERY:  insert into TrainingDataSet(sentenceId, sentence, ruleCorrectId, ruleCorrect, dateAdded)
          values(sentence, getSentenceFromID(sentence), tempRow.rulereviewid, tempRow.avg(rulereview), current_timestamp)
CONTEXT:  PL/pgSQL function sendtodataset(integer) line 11 at SQL statement
SQL state: 42703

基本上，我想知道是否可以在插入语句中使用该聚合函数，如果不能，是否有其他解决方法。

Answer 1

您不需要为此使用缓慢且低效的循环：

 insert into TrainingDataSet(sentenceId, sentence, ruleCorrectId, ruleCorrect, dateAdded)
 select getSentenceId(sentence), sentence, rulereviewid, avg(rulereview), current_timestamp
 from peoplereviews 
 where sentenceid = sentence
 group by rulereviewid

要回答原始问题：您需要为聚合提供一个正确的别名：

  FOR temprow IN
      select rulereviewid, avg(rulereview) as avg_views
      from peoplereviews 
      where sentenceid = sentence
      group by rulereviewid
  loop
      insert into TrainingDataSet(sentenceId, sentence, ruleCorrectId, ruleCorrect, dateAdded)
      values(sentence, getSentenceFromID(sentence), tempRow.rulereviewid, 
             tempRow.avg_views, current_timestamp);
  END LOOP;

您可以在 postgresql 存储过程中的插入语句中的临时行上引用聚合函数吗？

Can you reference an aggregate function on a temporary row in an insert statement within a stored procedure in postgresql?

postgresql-11