Question

表calendar_event中可以有多个日历事件（检查）。目前，我的查询返回的是最旧的检查（如果我们按字段ce.calendar_event_start对它们进行排序，则查询是最旧的），我希望它返回最新的（最新）检查。

我正在努力解决这个问题。我尝试在MAX周围添加ce.calendar_event_start，但这不起作用。我以为我必须更改LEFT JOIN，但我不知道如何更改它，以便它可以加入最新的ce.calendar_event_start值。

更新1 -感谢@Vinit

按照以下说明更改了LEFT JOIN，但是查询无法执行；

LEFT JOIN calendar_event ce
on ce.calendar_event_tenancy = t.tenancy_id 
AND ce.calendar_event_id = (SELECT calendar_event_id FROM
                                calendar_event ceInner
                                ceInner.calendar_event_tenancy = t.tenancy_id
                                AND ce.calendar_event_type='7' 
                                AND ce.calendar_event_status!='3'
                                ORDER BY ceInner.calendar_event_start DESC)

更新2 -我研究了@Vinit答案，提出了下面的建议！可以进一步改善吗？

按照以下说明更改了LEFT JOIN，但是查询无法执行；

LEFT JOIN calendar_event ce
on ce.calendar_event_tenancy = t.tenancy_id AND ce.calendar_event_id = (SELECT ceInner.calendar_event_id FROM
                                calendar_event ceInner
                                WHERE ceInner.calendar_event_tenancy = t.tenancy_id
                                AND ceInner.calendar_event_type='7' 
                                AND ceInner.calendar_event_status!='3'
                                ORDER BY ceInner.calendar_event_start DESC
                                LIMIT 1)

更新3 -我注意到该查询需要很长时间才能执行（大约10秒）。同一件事是否有更有效的版本？就在这里！见下文；

LEFT JOIN calendar_event ce
on ce.calendar_event_tenancy = t.tenancy_id AND ce.calendar_event_start  = (SELECT MAX(ceInner.calendar_event_start) FROM
                                calendar_event ceInner
                                WHERE ceInner.calendar_event_tenancy = t.tenancy_id
                                AND ceInner.calendar_event_type='7' 
                                AND ceInner.calendar_event_status!='3'
                                AND ceInner.calendar_event_inspection_type!='2')

查询；

SELECT t.*, ce.*, IF(ce.calendar_event_start IS NOT NULL, ce.calendar_event_start, t.tenancy_start_date) AS LastInspection
FROM tenancy t
LEFT JOIN calendar_event ce
on ce.calendar_event_tenancy = t.tenancy_id AND ce.calendar_event_type='7' AND ce.calendar_event_status!='3'
ORDER BY LastInspection ASC

表格和示例数据；

-- phpMyAdmin SQL Dump
-- version 4.7.7
-- https://www.phpmyadmin.net/
--
-- Host: localhost:3306
-- Generation Time: Jul 19, 2018 at 07:57 PM
-- Server version: 5.6.39
-- PHP Version: 5.6.30

SET SQL_MODE = "NO_AUTO_VALUE_ON_ZERO";
SET AUTOCOMMIT = 0;
START TRANSACTION;
SET time_zone = "+00:00";


/*!40101 SET @OLD_CHARACTER_SET_CLIENT=@@CHARACTER_SET_CLIENT */;
/*!40101 SET @OLD_CHARACTER_SET_RESULTS=@@CHARACTER_SET_RESULTS */;
/*!40101 SET @OLD_COLLATION_CONNECTION=@@COLLATION_CONNECTION */;
/*!40101 SET NAMES utf8mb4 */;

--
-- Database: `propsyst_main`
--

-- --------------------------------------------------------

--
-- Table structure for table `calendar_event`
--

CREATE TABLE `calendar_event` (
  `calendar_event_id` int(11) NOT NULL,
  `calendar_event_company_id` int(11) DEFAULT NULL,
  `calendar_event_branch_id` int(11) DEFAULT NULL,
  `calendar_event_subject` varchar(255) COLLATE utf8_bin DEFAULT NULL,
  `calendar_event_status` tinyint(4) DEFAULT NULL,
  `calendar_event_start` datetime DEFAULT NULL,
  `calendar_event_end` datetime DEFAULT NULL,
  `calendar_event_location` varchar(255) COLLATE utf8_bin DEFAULT NULL,
  `calendar_event_type` tinyint(4) DEFAULT NULL,
  `calendar_event_employee` int(11) DEFAULT NULL,
  `calendar_event_description` text COLLATE utf8_bin,
  `calendar_event_attendee_type` int(11) DEFAULT NULL,
  `calendar_event_property` int(11) DEFAULT NULL,
  `calendar_event_tenancy` int(11) DEFAULT NULL,
  `calendar_event_applicant` int(11) DEFAULT NULL,
  `calendar_event_valuation` int(11) DEFAULT NULL,
  `calendar_event_meet_at` tinyint(4) DEFAULT NULL,
  `calendar_event_date_created` datetime DEFAULT NULL,
  `calendar_event_date_updated` datetime DEFAULT NULL,
  `calendar_event_created_by` int(11) DEFAULT NULL,
  `calendar_event_updated_by` int(11) DEFAULT NULL,
  `calendar_event_feedback_position` text COLLATE utf8_bin,
  `calendar_event_feedback_pros` text COLLATE utf8_bin,
  `calendar_event_feedback_cons` text COLLATE utf8_bin,
  `calendar_event_feedback_confidence_level` tinyint(4) DEFAULT NULL,
  `calendar_event_feedback_public_comments` text COLLATE utf8_bin,
  `calendar_event_feedback_private_comments` text COLLATE utf8_bin,
  `calendar_event_confirmed_landlord_vendor` tinyint(4) DEFAULT NULL,
  `calendar_event_confirmed_applicant` tinyint(4) DEFAULT NULL,
  `calendar_event_notes` text COLLATE utf8_bin,
  `calendar_event_private_notes` text COLLATE utf8_bin,
  `calendar_event_branch` int(11) DEFAULT NULL,
  `calendar_event_recurring_id` int(11) DEFAULT NULL,
  `calendar_event_cancellation_reason` text COLLATE utf8_bin,
  `calendar_event_surveyor_company_name` varchar(255) COLLATE utf8_bin DEFAULT NULL,
  `calendar_event_surveyor_individual_name` varchar(255) COLLATE utf8_bin DEFAULT NULL,
  `calendar_event_surveyor_phone_number` varchar(20) COLLATE utf8_bin DEFAULT NULL,
  `calendar_event_directory` int(11) DEFAULT NULL,
  `calendar_event_inspection_type` tinyint(1) DEFAULT NULL,
  `calendar_event_survey_type` tinyint(4) DEFAULT NULL
) ENGINE=MyISAM DEFAULT CHARSET=utf8 COLLATE=utf8_bin;

--
-- Dumping data for table `calendar_event`
--

INSERT INTO `calendar_event` (`calendar_event_id`, `calendar_event_company_id`, `calendar_event_branch_id`, `calendar_event_subject`, `calendar_event_status`, `calendar_event_start`, `calendar_event_end`, `calendar_event_location`, `calendar_event_type`, `calendar_event_employee`, `calendar_event_description`, `calendar_event_attendee_type`, `calendar_event_property`, `calendar_event_tenancy`, `calendar_event_applicant`, `calendar_event_valuation`, `calendar_event_meet_at`, `calendar_event_date_created`, `calendar_event_date_updated`, `calendar_event_created_by`, `calendar_event_updated_by`, `calendar_event_feedback_position`, `calendar_event_feedback_pros`, `calendar_event_feedback_cons`, `calendar_event_feedback_confidence_level`, `calendar_event_feedback_public_comments`, `calendar_event_feedback_private_comments`, `calendar_event_confirmed_landlord_vendor`, `calendar_event_confirmed_applicant`, `calendar_event_notes`, `calendar_event_private_notes`, `calendar_event_branch`, `calendar_event_recurring_id`, `calendar_event_cancellation_reason`, `calendar_event_surveyor_company_name`, `calendar_event_surveyor_individual_name`, `calendar_event_surveyor_phone_number`, `calendar_event_directory`, `calendar_event_inspection_type`, `calendar_event_survey_type`) VALUES
(5170, 100, 0, 'Property Inspection (Rent Arrears) with Ms xxx xxx at Apartment 1 1 Howard Drive, Aigburth, Liverpool, L19 XXX', 2, '2017-07-28 14:30:00', '2017-07-28 14:45:00', 'Apartment 1 1 Howard Drive, Aigburth, Liverpool, L19 XXX', 7, 1, 'Tenant(s): Ms xxx xxx (Mobile: 00000000000, Email: no.email@mailinator.com)\r\nMeeting with: Agent (Michael Le Brocq)\r\nInspection Type: Rent Arrears\r\nPublic Notes: Property Inspection due to late rent\r\nStatus: Confirmed\r\nOriginally Arranged: 28/07/17 11:45:19 by Jane Nicholson\r\nLast Updated: 19/07/18 16:00:59 by Michael Le Brocq', 1, 172, 82, 0, 0, 0, '2017-07-28 11:45:19', '2018-07-19 16:00:59', 33, 1, '', NULL, NULL, NULL, NULL, NULL, 0, 0, 'Property Inspection due to late rent', '', 1, NULL, '', '', '', '', 0, 2, 0),
(5931, 100, 0, 'Property Inspection (Rent Arrears) with Ms Susan XXX at Apartment 1 1 Howard Drive, Aigburth, Liverpool, L19 XXX', 2, '2017-10-30 12:00:00', '2017-10-30 12:30:00', 'Apartment 1 1 Howard Drive, Aigburth, Liverpool, L19 XXX', 7, 1, 'Tenant(s): Ms Susan XXX (Mobile: 00000000000, Email: no.email@mailinator.com)\r\nMeeting with: Agent (Michael Le Brocq)\r\nInspection Type: Rent Arrears\r\nPublic Notes: Tenant not paid the rent\r\nStatus: Confirmed\r\nOriginally Arranged: 25/10/17 13:11:32 by Jane Nicholson\r\nLast Updated: 19/07/18 16:02:50 by Michael Le Brocq', 1, 172, 82, 0, 0, 0, '2017-10-25 13:11:32', '2018-07-19 16:02:50', 33, 1, '', NULL, NULL, NULL, NULL, NULL, 0, 0, 'Tenant not paid the rent', '', 1, NULL, '', '', '', '', 0, 2, 0),
(8929, 100, 0, 'Property Inspection (Routine) with Ms Susan XXX at Apartment 1 1 Howard Drive, Aigburth, Liverpool, L19 XXX', 2, '2018-07-25 15:00:00', '2018-07-25 15:15:00', 'Apartment 1 1 Howard Drive, Aigburth, Liverpool, L19 XXX', 7, 36, 'Tenant(s): Ms Susan XXX (Mobile: 00000000000, Email: no.email@mailinator.com)\r\nMeeting with: Agent (Jan Borrows)\r\nInspection Type: Routine\r\nPublic Notes: Confirmed with Diane\r\nStatus: Confirmed\r\nOriginally Arranged: 17/07/18 15:37:54 by Jan Borrows\r\nLast Updated: 17/07/18 15:37:54 by Jan Borrows', 1, 172, 82, 0, 0, 0, '2018-07-17 15:37:54', '2018-07-17 15:37:54', 36, 36, '', NULL, NULL, NULL, NULL, NULL, 0, 0, 'Confirmed with Diane', '', 1, NULL, NULL, '', '', '', 0, 1, 0);

--
-- Indexes for dumped tables
--

--
-- Indexes for table `calendar_event`
--
ALTER TABLE `calendar_event`
  ADD PRIMARY KEY (`calendar_event_id`),
  ADD UNIQUE KEY `calendar_event_id` (`calendar_event_id`),
  ADD KEY `calendar_event_status` (`calendar_event_status`),
  ADD KEY `calendar_event_start` (`calendar_event_start`),
  ADD KEY `calendar_event_end` (`calendar_event_end`),
  ADD KEY `calendar_event_property` (`calendar_event_property`),
  ADD KEY `calendar_event_employee` (`calendar_event_employee`),
  ADD KEY `calendar_event_type` (`calendar_event_type`),
  ADD KEY `calendar_event_company_id` (`calendar_event_company_id`),
  ADD KEY `calendar_event_branch_id` (`calendar_event_branch_id`),
  ADD KEY `calendar_event_attendee_type` (`calendar_event_attendee_type`),
  ADD KEY `calendar_event_applicant` (`calendar_event_applicant`),
  ADD KEY `calendar_event_valuation` (`calendar_event_valuation`),
  ADD KEY `calendar_event_meet_at` (`calendar_event_meet_at`),
  ADD KEY `calendar_event_branch` (`calendar_event_branch`),
  ADD KEY `calendar_event_recurring_id` (`calendar_event_recurring_id`);

--
-- AUTO_INCREMENT for dumped tables
--

--
-- AUTO_INCREMENT for table `calendar_event`
--
ALTER TABLE `calendar_event`
  MODIFY `calendar_event_id` int(11) NOT NULL AUTO_INCREMENT, AUTO_INCREMENT=8968;
COMMIT;

/*!40101 SET CHARACTER_SET_CLIENT=@OLD_CHARACTER_SET_CLIENT */;
/*!40101 SET CHARACTER_SET_RESULTS=@OLD_CHARACTER_SET_RESULTS */;
/*!40101 SET COLLATION_CONNECTION=@OLD_COLLATION_CONNECTION */;

AND

-- phpMyAdmin SQL Dump
-- version 4.7.7
-- https://www.phpmyadmin.net/
--
-- Host: localhost:3306
-- Generation Time: Jul 19, 2018 at 07:58 PM
-- Server version: 5.6.39
-- PHP Version: 5.6.30

SET SQL_MODE = "NO_AUTO_VALUE_ON_ZERO";
SET AUTOCOMMIT = 0;
START TRANSACTION;
SET time_zone = "+00:00";


/*!40101 SET @OLD_CHARACTER_SET_CLIENT=@@CHARACTER_SET_CLIENT */;
/*!40101 SET @OLD_CHARACTER_SET_RESULTS=@@CHARACTER_SET_RESULTS */;
/*!40101 SET @OLD_COLLATION_CONNECTION=@@COLLATION_CONNECTION */;
/*!40101 SET NAMES utf8mb4 */;

--
-- Database: `propsyst_main`
--

-- --------------------------------------------------------

--
-- Table structure for table `tenancy`
--

CREATE TABLE `tenancy` (
  `tenancy_id` int(11) NOT NULL,
  `tenancy_token` varchar(40) COLLATE utf8_bin DEFAULT NULL,
  `tenancy_type` tinyint(4) DEFAULT NULL,
  `tenancy_property` int(11) DEFAULT NULL,
  `tenancy_furnished` int(11) DEFAULT NULL,
  `tenancy_children` tinyint(4) DEFAULT NULL,
  `tenancy_pets` tinyint(4) DEFAULT NULL,
  `tenancy_smoking` tinyint(4) NOT NULL,
  `tenancy_property_part` tinyint(4) DEFAULT NULL,
  `tenancy_property_part_room` int(11) DEFAULT NULL,
  `tenancy_property_part_description` text COLLATE utf8_bin,
  `tenancy_shared_facilities` tinyint(4) DEFAULT NULL,
  `tenancy_shared_facilities_description` text COLLATE utf8_bin,
  `tenancy_agreement_date` date DEFAULT NULL,
  `tenancy_start_date` date DEFAULT NULL,
  `tenancy_fixed_term` smallint(6) DEFAULT NULL,
  `tenancy_fixed_term_unit` tinyint(4) DEFAULT NULL,
  `tenancy_fixed_term_end_date` date DEFAULT NULL,
  `tenancy_rent_amount` decimal(8,2) DEFAULT NULL,
  `tenancy_rent_frequency` int(11) DEFAULT NULL,
  `tenancy_rent_payable` int(11) DEFAULT NULL,
  `tenancy_rent_agreement` int(11) DEFAULT NULL,
  `tenancy_rent_frequency_schedule` text CHARACTER SET utf8,
  `tenancy_rent_payment_method` tinyint(4) DEFAULT NULL,
  `tenancy_council_pay_rent` tinyint(4) DEFAULT NULL,
  `tenancy_rent_vat_rate` tinyint(4) DEFAULT NULL,
  `tenancy_service_charge_amount` decimal(8,2) DEFAULT NULL,
  `tenancy_service_charge_frequency` int(11) DEFAULT NULL,
  `tenancy_service_charge_payable` int(11) DEFAULT NULL,
  `tenancy_service_charge_agreement` int(11) DEFAULT NULL,
  `tenancy_service_charge_frequency_schedule` text COLLATE utf8_bin,
  `tenancy_service_charge_payment_method` tinyint(4) DEFAULT NULL,
  `tenancy_service_charge_vat_rate` tinyint(4) DEFAULT NULL,
  `tenancy_insurance_amount` decimal(8,2) DEFAULT NULL,
  `tenancy_insurance_frequency` int(11) DEFAULT NULL,
  `tenancy_insurance_payable` int(11) DEFAULT NULL,
  `tenancy_insurance_agreement` int(11) DEFAULT NULL,
  `tenancy_insurance_frequency_schedule` text COLLATE utf8_bin,
  `tenancy_insurance_payment_method` tinyint(4) DEFAULT NULL,
  `tenancy_insurance_vat_rate` tinyint(4) DEFAULT NULL,
  `tenancy_notes` text COLLATE utf8_bin,
  `tenancy_agent_branch` int(11) DEFAULT NULL,
  `tenancy_agent_employee` int(11) DEFAULT NULL,
  `tenancy_letting_service` tinyint(4) DEFAULT NULL,
  `tenancy_tenant_find_fee` decimal(10,2) DEFAULT NULL,
  `tenancy_tenant_find_fee_type` tinyint(4) DEFAULT NULL,
  `tenancy_management_fee` decimal(10,2) DEFAULT NULL,
  `tenancy_management_fee_type` tinyint(4) DEFAULT NULL,
  `tenancy_tenant_fee` decimal(6,2) DEFAULT NULL,
  `tenancy_guarantor_fee` decimal(6,2) DEFAULT NULL,
  `tenancy_reminder_letter_fee` decimal(6,2) DEFAULT NULL,
  `tenancy_missed_payment_fee` decimal(6,2) DEFAULT NULL,
  `tenancy_gas` tinyint(4) DEFAULT NULL,
  `tenancy_electricity` tinyint(4) DEFAULT NULL,
  `tenancy_water` tinyint(4) DEFAULT NULL,
  `tenancy_oil` tinyint(4) DEFAULT NULL,
  `tenancy_telephone` tinyint(4) DEFAULT NULL,
  `tenancy_broadband` tinyint(4) DEFAULT NULL,
  `tenancy_tv_licence` tinyint(4) DEFAULT NULL,
  `tenancy_sat_cable_tv` tinyint(4) DEFAULT NULL,
  `tenancy_council_tax` tinyint(4) DEFAULT NULL,
  `tenancy_service_charge` tinyint(4) DEFAULT NULL,
  `tenancy_ground_rent` tinyint(4) DEFAULT NULL,
  `tenancy_deposit_required` tinyint(4) DEFAULT NULL,
  `tenancy_deposit_amount` decimal(8,2) DEFAULT NULL,
  `tenancy_deposit_protection_responsible` tinyint(4) DEFAULT NULL,
  `tenancy_deposit_protection_scheme` tinyint(4) DEFAULT NULL,
  `tenancy_status` tinyint(4) DEFAULT NULL,
  `tenancy_renewal_status` tinyint(4) DEFAULT '4',
  `tenancy_renewal_notes` text COLLATE utf8_bin,
  `tenancy_move_out_date` date DEFAULT NULL,
  `tenancy_move_out_reason` tinyint(4) DEFAULT NULL,
  `tenancy_move_out_notes` text COLLATE utf8_bin,
  `tenancy_tenant_find_with_management_fee` decimal(7,2) DEFAULT NULL,
  `tenancy_tenant_find_with_management_fee_type` tinyint(4) DEFAULT NULL,
  `tenancy_overdue_tc_reminders` tinyint(4) NOT NULL DEFAULT '1',
  `tenancy_student` tinyint(4) DEFAULT NULL,
  `tenancy_inspection_frequency` tinyint(4) DEFAULT NULL,
  `tenancy_move_out_employee` int(11) DEFAULT NULL
) ENGINE=MyISAM DEFAULT CHARSET=utf8 COLLATE=utf8_bin;

--
-- Dumping data for table `tenancy`
--

INSERT INTO `tenancy` (`tenancy_id`, `tenancy_token`, `tenancy_type`, `tenancy_property`, `tenancy_furnished`, `tenancy_children`, `tenancy_pets`, `tenancy_smoking`, `tenancy_property_part`, `tenancy_property_part_room`, `tenancy_property_part_description`, `tenancy_shared_facilities`, `tenancy_shared_facilities_description`, `tenancy_agreement_date`, `tenancy_start_date`, `tenancy_fixed_term`, `tenancy_fixed_term_unit`, `tenancy_fixed_term_end_date`, `tenancy_rent_amount`, `tenancy_rent_frequency`, `tenancy_rent_payable`, `tenancy_rent_agreement`, `tenancy_rent_frequency_schedule`, `tenancy_rent_payment_method`, `tenancy_council_pay_rent`, `tenancy_rent_vat_rate`, `tenancy_service_charge_amount`, `tenancy_service_charge_frequency`, `tenancy_service_charge_payable`, `tenancy_service_charge_agreement`, `tenancy_service_charge_frequency_schedule`, `tenancy_service_charge_payment_method`, `tenancy_service_charge_vat_rate`, `tenancy_insurance_amount`, `tenancy_insurance_frequency`, `tenancy_insurance_payable`, `tenancy_insurance_agreement`, `tenancy_insurance_frequency_schedule`, `tenancy_insurance_payment_method`, `tenancy_insurance_vat_rate`, `tenancy_notes`, `tenancy_agent_branch`, `tenancy_agent_employee`, `tenancy_letting_service`, `tenancy_tenant_find_fee`, `tenancy_tenant_find_fee_type`, `tenancy_management_fee`, `tenancy_management_fee_type`, `tenancy_tenant_fee`, `tenancy_guarantor_fee`, `tenancy_reminder_letter_fee`, `tenancy_missed_payment_fee`, `tenancy_gas`, `tenancy_electricity`, `tenancy_water`, `tenancy_oil`, `tenancy_telephone`, `tenancy_broadband`, `tenancy_tv_licence`, `tenancy_sat_cable_tv`, `tenancy_council_tax`, `tenancy_service_charge`, `tenancy_ground_rent`, `tenancy_deposit_required`, `tenancy_deposit_amount`, `tenancy_deposit_protection_responsible`, `tenancy_deposit_protection_scheme`, `tenancy_status`, `tenancy_renewal_status`, `tenancy_renewal_notes`, `tenancy_move_out_date`, `tenancy_move_out_reason`, `tenancy_move_out_notes`, `tenancy_tenant_find_with_management_fee`, `tenancy_tenant_find_with_management_fee_type`, `tenancy_overdue_tc_reminders`, `tenancy_student`, `tenancy_inspection_frequency`, `tenancy_move_out_employee`) VALUES
(82, 'aJ9GCrxk9IEkBkLUqxsTuIdlbHnGNXTc4coq69AW', 1, 172, 2, 0, 0, 0, 1, 0, '', 0, '', '2014-08-21', '2014-08-21', 6, 2, '2015-02-20', '395.00', 3, 3, 1, '', 3, 0, 0, '0.00', 0, 0, 0, '', 0, 0, '0.00', 0, 0, 0, '', 0, 0, '', 1, 1, 3, '225.00', 1, '10.00', 2, '70.00', '50.00', '5.00', '15.00', 2, 2, 2, 3, 2, 2, 2, 2, 2, 3, 3, 1, '500.00', 1, 1, 1, 1, NULL, '0000-00-00', 0, '', '239.00', 1, 1, 0, 12, NULL);

--
-- Indexes for dumped tables
--

--
-- Indexes for table `tenancy`
--
ALTER TABLE `tenancy`
  ADD PRIMARY KEY (`tenancy_id`),
  ADD UNIQUE KEY `tenancy_token` (`tenancy_token`),
  ADD KEY `tenancy_id` (`tenancy_id`),
  ADD KEY `tenancy_property` (`tenancy_property`),
  ADD KEY `tenancy_status` (`tenancy_status`),
  ADD KEY `tenancy_letting_service` (`tenancy_letting_service`);

--
-- AUTO_INCREMENT for dumped tables
--

--
-- AUTO_INCREMENT for table `tenancy`
--
ALTER TABLE `tenancy`
  MODIFY `tenancy_id` int(11) NOT NULL AUTO_INCREMENT, AUTO_INCREMENT=526;
COMMIT;

/*!40101 SET CHARACTER_SET_CLIENT=@OLD_CHARACTER_SET_CLIENT */;
/*!40101 SET CHARACTER_SET_RESULTS=@OLD_CHARACTER_SET_RESULTS */;
/*!40101 SET COLLATION_CONNECTION=@OLD_COLLATION_CONNECTION */;

Answer 1

日期上的order by栏应该降序以获取最新的检查日期

ORDER BY LastInspection DESC

编辑您可以尝试此查询-

SELECT t.*, 
ce.*, 
IF(
   ce.calendar_event_start IS NOT NULL, 
   ce.calendar_event_start, 
   t.tenancy_start_date
) AS LastInspection
FROM tenancy t
LEFT JOIN calendar_event ce
on ce.calendar_event_tenancy = t.tenancy_id 
    AND ce.calendar_event_start  = (select max(ceInner.calendar_event_start) from -- get the recent event id
                                calendar_event ceInner
                                ceInner.calendar_event_tenancy = t.tenancy_id
                                AND ceInner.calendar_event_type='7' 
                                AND ceInner.calendar_event_status!='3'
                                )

ORDER BY LastInspection DESC

MySQL保留最大价值

1 个答案: