Mysql 如何根据其他联接表条件选择某些表字段的总和？

我一直在做一个费用跟踪系统。我有三个主要表格：“费用”、“费用报告”、“付款”

我的数据库结构如下：

• “费用”属于一个“费用报告”
• “费用报告”有许多“费用”
• “费用报告”属于许多“付款”
• “付款”属于许多“费用报告”

我为“费用报告”和“付款”表添加了一个数据透视表，即“费用报告付款”，以处理多对多关系“费用报告付款”表包含ff字段：

• 身份证
• 费用报告id
• 付款id
• 付款

这是我获取费用和付款总额的查询：

SELECT 
  IFNULL(SUM(ex.`amount`), 0) AS total_expenses,
  IFNULL(SUM(erp.`payment`), 0) AS total_payment 
FROM
  `expenses` ex 
  JOIN `expense_reports` er 
    ON er.`id` = ex.`expense_report_id` 
  LEFT JOIN `expense_report_payment` erp 
    ON erp.`expense_report_id` = er.`id` 
  JOIN `payments` p 
    ON p.`id` = erp.`payment_id` 
    AND p.`deleted_at` IS NULL 
    AND p.`cancelled_at` IS NULL 
    AND p.`received_at` IS NOT NULL 
WHERE ex.`deleted_at` IS NULL 
  AND er.`deleted_at` IS NULL 
  AND er.`rejected_at` IS NULL 
  AND er.`cancelled_at` IS NULL 

---

如果有收到的付款（总费用=100；总付款=100），我会得到总金额。但是，如果尚未收到付款，则费用和付款的总金额均为零。

左联接

表格。通常，您还应该将右侧联接表上的

WHERE

条件移动到

LEFT JOIN

s

on

子句。试一试

SELECT 
  IFNULL(SUM(ex.`amount`), 0) AS total_expenses,
  IFNULL(SUM(erp.`payment`), 0) AS total_payment 
FROM
  `expenses` ex 
  LEFT JOIN `expense_reports` er 
    ON er.`id` = ex.`expense_report_id` 
      AND er.`deleted_at` IS NULL 
      AND er.`rejected_at` IS NULL 
      AND er.`cancelled_at` IS NULL    
  LEFT JOIN `expense_report_payment` erp 
    ON erp.`expense_report_id` = er.`id` 
  LEFT JOIN `payments` p 
    ON p.`id` = erp.`payment_id` 
    AND p.`deleted_at` IS NULL 
    AND p.`cancelled_at` IS NULL 
    AND p.`received_at` IS NOT NULL 
WHERE ex.`deleted_at` IS NULL 
  

---

左联接

表。通常，您还应该将右侧联接表上的

WHERE

条件移动到

LEFT JOIN

s

on

子句。试一试

SELECT 
  IFNULL(SUM(ex.`amount`), 0) AS total_expenses,
  IFNULL(SUM(erp.`payment`), 0) AS total_payment 
FROM
  `expenses` ex 
  LEFT JOIN `expense_reports` er 
    ON er.`id` = ex.`expense_report_id` 
      AND er.`deleted_at` IS NULL 
      AND er.`rejected_at` IS NULL 
      AND er.`cancelled_at` IS NULL    
  LEFT JOIN `expense_report_payment` erp 
    ON erp.`expense_report_id` = er.`id` 
  LEFT JOIN `payments` p 
    ON p.`id` = erp.`payment_id` 
    AND p.`deleted_at` IS NULL 
    AND p.`cancelled_at` IS NULL 
    AND p.`received_at` IS NOT NULL 
WHERE ex.`deleted_at` IS NULL 
  

---

谢谢大家的帮助。我通过在左联接中联接“费用报告付款”和“付款”表，成功地解决了这个问题

SELECT 
  IFNULL(SUM(ex.`amount`), 0) AS total_expenses,
  IFNULL(SUM(erp.payment), 0) AS total_payment
FROM
  `expenses` ex 
  JOIN `expense_reports` er 
    ON er.`id` = ex.`expense_report_id` 
    AND er.`deleted_at` IS NULL 
    AND er.`rejected_at` IS NULL 
    AND er.`cancelled_at` IS NULL 
  LEFT JOIN 
    (SELECT 
      ep.*
    FROM
      `expense_report_payment` ep 
      JOIN `payments` p 
        ON p.`id` = ep.`payment_id`
    WHERE p.`received_at` IS NOT NULL
    AND p.`deleted_at` IS NULL
    AND p.`cancelled_at` IS NULL
    ) AS erp 
    ON erp.expense_report_id = er.`id` 
WHERE ex.`deleted_at` IS NULL 

---

谢谢大家的帮助。我通过在左联接中联接“费用报告付款”和“付款”表，成功地解决了这个问题

SELECT 
  IFNULL(SUM(ex.`amount`), 0) AS total_expenses,
  IFNULL(SUM(erp.payment), 0) AS total_payment
FROM
  `expenses` ex 
  JOIN `expense_reports` er 
    ON er.`id` = ex.`expense_report_id` 
    AND er.`deleted_at` IS NULL 
    AND er.`rejected_at` IS NULL 
    AND er.`cancelled_at` IS NULL 
  LEFT JOIN 
    (SELECT 
      ep.*
    FROM
      `expense_report_payment` ep 
      JOIN `payments` p 
        ON p.`id` = ep.`payment_id`
    WHERE p.`received_at` IS NOT NULL
    AND p.`deleted_at` IS NULL
    AND p.`cancelled_at` IS NULL
    ) AS erp 
    ON erp.expense_report_id = er.`id` 
WHERE ex.`deleted_at` IS NULL 

---

在连接链中，必须在第一个连接后使用左连接<代码>付款已加入到<代码>费用_报表_付款，因此它位于左连接链中，并且必须左连接。必须在连接链中的第一个后使用左连接<代码>付款已加入到<代码>费用_报告_付款，因此它位于leftjoined链中，必须也加入leftjoined。感谢您的回复。我尝试了你的建议，但它仍然显示付款，即使付款尚未收到。这就是为什么我首先加入了“付款”表和“费用报告付款”表的原因。谢谢您的回复。我尝试了你的建议，但它仍然显示付款，即使付款尚未收到。这就是为什么我首先加入了“付款”表和“费用报告付款”表。