我已经提供了我的表的摘要,并且我已经在SQL上有了一个良好的开端,但我仍然坚持要弄清楚如何限制返回的项目数量。我应该可以选择一个或多个条款,并从这些条款中取回余额。
学生应该有1条记录,他们可以在几个条款上进行多次预订,但是付款不是针对预订而是针对学生。那是让我失望的部分。
表结构,日期和我的SQL的开始。有人可以帮我吗?这个结果不应该显示Sue Smith从第3学期支付的500美元。
我正在使用PostgreSQL,但我认为这是一个非常基本的问题,不需要Postgres特有的任何内容。
Student ID Last First Total Fees Reservation Count Amount Paid Amount Due
123456 Jones Amy 50 1 50 0
412365 Smith Sue 100 3 545 -445
741258 Anderson Jon 50 1 0.00 50.00
963258 Holmes Fred 100 2 30 70
SET search_path TO temp, public;
CREATE TABLE term
(term_id SERIAL PRIMARY KEY,
term_title VARCHAR(100));
CREATE TABLE student
(student_id SERIAL PRIMARY KEY,
student_sis_id VARCHAR(15),
student_first_name VARCHAR(30),
student_last_name VARCHAR(100));
CREATE TABLE reservation
(reservation_id SERIAL PRIMARY KEY,
student_id INTEGER REFERENCES student ON UPDATE CASCADE,
term_id INTEGER REFERENCES term ON UPDATE CASCADE,
reservation_fee_amount NUMERIC DEFAULT 0.00);
CREATE TABLE payment
(payment_id SERIAL PRIMARY KEY,
student_id INTEGER REFERENCES student ON UPDATE CASCADE,
term_id INTEGER REFERENCES term ON UPDATE CASCADE,
payment_cash_amount NUMERIC,
payment_credit_card_amount NUMERIC,
payment_check_amount NUMERIC);
INSERT INTO term VALUES (DEFAULT, 'SESSION 1');
INSERT INTO term VALUES (DEFAULT, 'SESSION 2');
INSERT INTO term VALUES (DEFAULT, 'SESSION 3');
INSERT INTO student VALUES (DEFAULT, 412365, 'Sue', 'Smith');
INSERT INTO student VALUES (DEFAULT, 123456, 'Amy', 'Jones');
INSERT INTO student VALUES (DEFAULT, 741258, 'Jon', 'Anderson');
INSERT INTO student VALUES (DEFAULT, 963258, 'Fred', 'Holmes');
INSERT INTO reservation VALUES (DEFAULT, 1, 1, 50);
INSERT INTO reservation VALUES (DEFAULT, 1, 2, 50);
INSERT INTO reservation VALUES (DEFAULT, 2, 1, 50);
INSERT INTO reservation VALUES (DEFAULT, 3, 2, 50);
INSERT INTO reservation VALUES (DEFAULT, 4, 1, 50);
INSERT INTO reservation VALUES (DEFAULT, 4, 2, 50);
INSERT INTO reservation VALUES (DEFAULT, 1, 3, 50);
INSERT INTO payment VALUES (DEFAULT, 1, 1, 25, 0, 0);
INSERT INTO payment VALUES (DEFAULT, 1, 1, 0, 20, 0);
INSERT INTO payment VALUES (DEFAULT, 2, 1, 25, 25, 0);
INSERT INTO payment VALUES (DEFAULT, 4, 1, 10, 10, 10);
INSERT INTO payment VALUES (DEFAULT, 1, 3, 500, 0, 0);
SELECT
student.student_sis_id AS "Student ID",
student.student_last_name AS Last,
student.student_first_name AS First,
SUM(reservation.reservation_fee_amount) AS "Total Fees",
(
SELECT COUNT(reservation.reservation_id)
FROM reservation
WHERE student.student_id = reservation.student_id
) AS "Reservation Count",
(
SELECT
COALESCE(SUM(
payment.payment_check_amount
+ payment.payment_cash_amount
+ payment.payment_credit_card_amount
), 0.00)
FROM payment
WHERE payment.student_id = student.student_id
) AS "Amount Paid",
SUM(reservation.reservation_fee_amount) - (
SELECT
COALESCE(SUM(
payment.payment_check_amount
+ payment.payment_cash_amount
+ payment.payment_credit_card_amount
), 0.00)
FROM payment WHERE payment.student_id = student.student_id
) AS "Amount Due"
FROM
student
INNER JOIN reservation ON student.student_id = reservation.student_id
WHERE reservation.term_id IN (1,2)
GROUP BY
student.student_id,
student.student_sis_id,
student.student_last_name,
student.student_first_name
ORDER BY
student.student_sis_id
;
答案 0 :(得分:1)
以下是我更新的查询版本:
SELECT
s.student_sis_id AS "Student ID",
s.student_last_name AS Last,
s.student_first_name AS First,
SUM(r.reservation_fee_amount) AS "Total Fees",
COUNT(r.reservation_id) AS "Reservation Count",
COALESCE(
SUM(
p.payment_check_amount
+ p.payment_cash_amount
+ p.payment_credit_card_amount
), 0.00
) AS "Amount Paid",
SUM(r.reservation_fee_amount) - (
COALESCE(
SUM(
p.payment_check_amount
+ p.payment_cash_amount
+ p.payment_credit_card_amount
), 0.00
)
) AS "Amount Due"
FROM
student s
INNER JOIN reservation r ON s.student_id = r.student_id
LEFT JOIN payment p ON p.student_id = r.student_id AND p.term_id = r.term_id
WHERE r.term_id IN (1,2)
GROUP BY
s.student_id,
s.student_sis_id,
s.student_last_name,
s.student_first_name
ORDER BY
s.student_sis_id
;
值得关注的事情:
我在主(外部)查询中包含payments
以避免子查询
联接类型为LEFT [OUTER] JOIN
,因此缺少任何payment
行不会阻止其他数据出现在结果集中
加入条件包括term_id
(基本上这就是你迷路的地方,我认为)
最后我使用短表别名来提高可读性。
我希望这就是你所追求的目标。
答案 1 :(得分:1)
找到2付款条目问题的解决方案(我原来的问题中没有认出)。这是答案:
set search_path to temp, public;
SELECT
s.student_sis_id AS "Student ID",
s.student_last_name AS "Last Name",
s.student_first_name AS "First Name",
SUM(r.reservation_fee_amount) AS "Total Fees",
COALESCE(p.paid, 0.00) AS "Amount Paid",
COALESCE(SUM(r.reservation_fee_amount) - p.paid, 0.00) AS "Amount Due"
FROM
student s
INNER JOIN reservation r ON s.student_id = r.student_id
left outer join
(
select student_id, term_id,
SUM(
p.payment_check_amount
+ p.payment_cash_amount
+ p.payment_credit_card_amount
) AS "paid"
from payment p
group by student_id, term_id
) as p
ON p.student_id = r.student_id AND p.term_id = r.term_id
WHERE r.reservation_completed AND r.term_id IN (1,2)
GROUP BY
s.student_sis_id,
s.student_last_name,
s.student_first_name,
p.paid
ORDER BY
s.student_sis_id
谢谢你dezso和davek