尝试将 select sum 和 count 语句合并为一个（oracle db）答案

【问题标题】：Trying to combine select sum and count statemenents into one (oracle db)尝试将 select sum 和 count 语句合并为一个（oracle db）
【发布时间】：2015-12-23 19:50:37
【问题描述】：

我需要编写一个语句来获取客户总数和所有帐户的总和。我能够单独做每一个，但我不能让它们成为一个陈述。错误信息是什么意思，FROM应该去哪里？

这是贷款总额的报表

SQL> SELECT SUM(amount) as "total"
     FROM loan, borrower
     WHERE borrower.loan_number = loan.loan_number;

这是客户数量的报表

   SQL> SELECT COUNT(*)
        FROM customer;

我已经像这样将它们组合在一起，但我收到一条错误消息，如您所见。

> SQL> SELECT
2  (SELECT COUNT(*) as "Total Customers" from customer)
3  (SELECT SUM(amount) as "Total Loan Values"
4  FROM borrower, loan 
5  WHERE borrower.loan_number = loan.number);
(select sum(amount) as "Total Loan Values"
 *
 ERROR at line 3:
 ORA-00923: FROM keyword not found where expected

【问题讨论】：

标签： sql oracle select join

【解决方案1】：

由于您对customer 的查询仅返回一行，您可以将cross join 与另一个问题一起使用：

SELECT     SUM(amount) as total, cnt
FROM       loan
JOIN       borrower ON borrower.loan_number = loan.loan_number;
CROSS JOIN (SELECT COUNT(*) AS cnt 
            FROM   customer)

【讨论】：

【解决方案2】：

您可以像下面这样修改您的查询

SELECT
(SELECT COUNT(*) as "Total Customers" from customer),
(SELECT SUM(amount) as "Total Loan Values"
FROM borrower, loan 
WHERE borrower.loan_number = loan.number)
FROM DUAL;

【讨论】：

【解决方案3】：

试试这个：

SELECT
  (SELECT COUNT(*) as "Total Customers" from customer),
  (SELECT SUM(amount) as "Total Loan Values"
  FROM borrower, loan 
  WHERE borrower.loan_number = loan.number)
FROM DUAL;

你少了一个逗号；此外，您总是需要一个 FROM 子句。如果没有要命名的表，则将 DUAL 用作虚拟对象。

【讨论】：