试试这个
:在使用set操作时,我们必须遵循以下三点
1-UNION中的每个SELECT语句必须具有相同的列数
2-列还必须具有类似的数据类型
3-每个SELECT语句中的列的顺序也必须相同
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