MYSQL：联合运算符添加“总计”行答案

【问题标题】：MYSQL: Union operator to add a 'total' rowMYSQL：联合运算符添加“总计”行
【发布时间】：2017-11-28 11:37:18
【问题描述】：

我创建了以下 SQL 查询来计算未来 12 个月内的租赁总收入。

SELECT DISTINCT apartment.addressLine1, lease.monthlyRent, lease.duration,  lease.roomNumber, lease.monthlyRent*lease.duration AS totalLeaseRent
    FROM `lease`
    INNER JOIN apartment on (lease.roomNumber) = (apartment.roomNumber)
    left Join tenantLease on tenantLease.leaseID = lease.leaseID
    WHERE tenantLease.live = 1 AND lease.duration <= 12

这将返回以下结果：

AddressLine1    monthlyRent Duration(months)  roomNumber    totalLeaseRent
Chlorine Gardens1200        9                 GF02          10800
May Road        800         12                GF03          9600
Beech Hill      900         8                 BG06          7200
Ash Avenue      1000        12                AA04          12000

我现在希望能够有另一行来包含 totalLeaseRent 的总数。像这样：

AddressLine1    monthlyRent Duration(months)  roomNumber    totalLeaseRent
    Chlorine Garden1200     9                 GF02          10800
    May Road        800         12            GF03          9600
    Beech Hill      900         8             BG06          7200
    Ash Avenue      1000        12            AA04          12000
    TOTAL                                                   *total*

我尝试了以下代码，但不断收到错误代码： 1222 - 使用的 SELECT 语句有不同的列数

SELECT DISTINCT apartment.addressLine1, lease.monthlyRent, lease.duration,  lease.roomNumber, lease.monthlyRent*lease.duration AS totalLeaseRent
FROM `lease`
INNER JOIN apartment on (lease.roomNumber) = (apartment.roomNumber)
left Join tenantLease on tenantLease.leaseID = lease.leaseID
WHERE tenantLease.live = 1 AND lease.duration <= 12

UNION ALL
SELECT 'Total', SUM(lease.monthlyRent * lease.duration)
FROM lease

如何让这个查询运行？谢谢

【问题讨论】：

标签： mysql phpmyadmin union

【解决方案1】：

试试这个：我们在使用集合操作时必须遵循以下三点

1- UNION 中的每个 SELECT 语句必须具有相同的列数

2- 列也必须具有相似的数据类型

3- 每个 SELECT 语句中的列也必须是相同的顺序

SELECT DISTINCT apartment.addressLine1, 
    lease.monthlyRent, 
    lease.duration,  
    lease.roomNumber, 
    lease.monthlyRent*lease.duration AS totalLeaseRent
FROM `lease`
INNER JOIN apartment on (lease.roomNumber) = (apartment.roomNumber)
left Join tenantLease on tenantLease.leaseID = lease.leaseID
WHERE tenantLease.live = 1 AND lease.duration <= 12
UNION ALL
SELECT 'Total', NULL, NULL, NULL, SUM(lease.monthlyRent * lease.duration)
FROM lease

【讨论】：

这行得通！非常感谢，我花了很多时间来解决这个问题！