在以2表和3日期字段聯接的情況下按降序獲取多個日期的問題

Question

我想列出2表和3 diffrener日期字段的記錄，我在查詢下面運行

SELECT id, register.reg_date ,payment_history.payment_date ,paymentcancel_date  
FROM register 
LEFT JOIN payment_history ON payment_history.r_id = register.id 
WHERE user_type = 'Landlord' 
ORDER BY GREATEST(reg_date,paymentcancel_date,payment_date) DESC

我得到如下圖所示的輸出

但在上面的輸出日期不是降序排列的，我想像下面的格式輸出

編輯

SELECT id, register.reg_date ,payment_history.payment_date ,paymentcancel_date  from register  left join  payment_history on payment_history.r_id = register.id where user_type = 'Landlord' ORDER BY COALESCE(reg_date, '2000-01-01') desc,
              COALESCE(paymentcancel_date, '2000-01-01') desc,
              COALESCE(payment_date, '2000-01-01')
              desc

Answer 1

唉， GREATEST()返回NULL如果任何參數為NULL 。 因此，一種方法是這樣的：

ORDER BY GREATEST(COALESCE(reg_date, '2000-01-01'),
                  COALESCE(paymentcancel_date, '2000-01-01'),
                  COALESCE(payment_date, '2000-01-01')
                 ) desc

Answer 2

我通過下面的代碼解決我的問題

$res= $this->property_model->get_all_array("SELECT reg_date as date,f_name,id as id from register order by reg_date desc");
$res1= $this->property_model->get_all_array("SELECT payment_date as date,history_id,r_id as id from payment_history order by payment_date desc");
$data['activity'] = array_merge($res,$res1);

foreach ($activity as $key => $row) {
$volume[$key]  = $row['date'];
}

// Sort the data with volume descending, edition ascending
// Add $data as the last parameter, to sort by the common key
array_multisort($volume, SORT_DESC, $activity);