Question

我需要创建一个计算每个分支的帐户总和并进行比较的函数分支平衡。

我试着这样做：

CREATE OR REPLACE FUNCTION t3() RETURNS TABLE(bb integer, sum integer) AS $$ 
BEGIN
FOR i IN 1..50 LOOP
BEGIN
SELECT bbalance FROM branch WHERE branchid = i
union
SELECT  sum(balance) FROM account WHERE branch = i;
END;
END LOOP;
END;
$$ LANGUAGE plpgsql;

我现在有点困惑...我希望它返回一个包含2列的表：一个具有来自分支的bbalance值;第二个是该分支中每个余额的总和。

我需要一些可以使用select * from t3()调用的内容。

这就是我在pgAdmin查询编辑器中写的内容：

CREATE OR REPLACE FUNCTION t3() RETURNS TABLE(bb integer, sum integer) AS $$ 
DECLARE
   bal integer;
BEGIN
  FOR i IN SELECT branchid FROM branch
  LOOP
    SELECT INTO bb bbalance FROM branch WHERE branchid = i;
    SELECT INTO "sum" sum(balance) FROM account WHERE branch = i;
    RETURN NEXT;
  END LOOP;
  RETURN;
END;
$$ LANGUAGE plpgsql;

错误是：

ERRORE:  variabile del ciclo sulle righe deve essere una variabile di tipo row o record o una lista di variabili scalari
LINE 5:   FOR i IN SELECT branchid FROM branch
              ^

********** Error **********

ERRORE: variabile del ciclo sulle righe deve essere una variabile di tipo row o record o una lista di variabili scalari
SQL state: 42601
Character: 119

意大利语 - 翻译是：
循环遍历行的循环变量必须是记录或行变量或标量变量列表。

Answer 1

您需要设置表变量而不是RETURN NEXT，例如

CREATE OR REPLACE FUNCTION t3() RETURNS TABLE(bb integer, sum integer) AS $$ 
DECLARE
   i integer;
BEGIN
  FOR i IN SELECT branchid FROM branch
  LOOP
    SELECT INTO bb bbalance FROM branch WHERE branchid = i;
    SELECT INTO "sum" sum(balance) FROM account WHERE branch = i;
    RETURN NEXT;
  END LOOP;
  RETURN;
END;
$$ LANGUAGE plpgsql;

但实际上，如果没有PL / PgSQL作为一个简单的GROUP BY来加入，所有这一切都可以更加干净地完成：

SELECT b.branchid, b.bbalance, coalesce(sum(a.balance), 0) AS acctbalance
FROM branch b LEFT OUTER JOIN account a ON (b.branchid = a.branch)
GROUP BY b.branchid;

BTW，“sum”是参数名称的不良选择，因为它是一种常用的内置聚合函数。

PostgreSQL函数返回一个表

1 个答案: