MySQL查詢，刪除行如果兩個字段爲空

Question

我有一個查詢，顯示這樣的結果：

Zip | Left Price | Right Price 
17901 | 100.00  | null 
17820 | null  | 40.00 
54353 | null  | null 
53133 | 40.00  | 542.00 

如何刪除那些左，價格價格爲空的結果。所以我不想讓這裏的郵編54353甚至顯示在結果中。

以下是我做了我的查詢：

SELECT contacts.zip, CASE WHEN 
left_return_date IS NULL AND left_delivery_date IS NOT NULL AND left_price 
IS NOT NULL THEN left_price ELSE null END AS left_price, CASE WHEN 
right_return_date IS NULL AND right_delivery_date IS NOT NULL AND 
right_price IS NOT NULL THEN right_price ELSE null END AS right_price 
FROM invoice_hearing_aids 
LEFT JOIN invoices ON invoices.ID = invoice_hearing_aids.invoice_id 
LEFT JOIN contacts ON contacts.id = invoices.contact_id 
WHERE 
trial_complete = 'Y' 
AND invoices.company_id = '1' 
AND invoices.date_issued >= DATE_SUB(NOW(),INTERVAL 1 YEAR) 

Answer 1

您可以在結尾處添加HAVING條款，如：

SELECT contacts.zip, CASE WHEN 
left_return_date IS NULL AND left_delivery_date IS NOT NULL AND left_price 
IS NOT NULL THEN left_price ELSE null END AS left_price, CASE WHEN 
right_return_date IS NULL AND right_delivery_date IS NOT NULL AND 
right_price IS NOT NULL THEN right_price ELSE null END AS right_price 
FROM invoice_hearing_aids 
LEFT JOIN invoices ON invoices.ID = invoice_hearing_aids.invoice_id 
LEFT JOIN contacts ON contacts.id = invoices.contact_id 
WHERE 
trial_complete = 'Y' 
AND invoices.company_id = '1' 
AND invoices.date_issued >= DATE_SUB(NOW(),INTERVAL 1 YEAR) 
HAVING 
    right_price IS NOT NULL OR left_price IS NOT NULL 

這將正常工作，如果你有相對較少的這種無用的記錄（我最多可以完成結果集大小的50％）。如果還有更多這樣的記錄，那麼我會仔細查看查詢，並且很可能會修改條件。

Answer 2

執行該left_price和right_price是你可以ADDA列值AFCT where條件

SELECT contacts.zip, 
     CASE WHEN left_return_date IS NULL 
      AND left_delivery_date IS NOT NULL 
      AND left_price IS NOT NULL THEN left_price 
      ELSE null END AS left_price, 
     CASE WHEN right_return_date IS NULL 
      AND right_delivery_date IS NOT NULL 
      AND right_price IS NOT NULL THEN right_price 
      ELSE null END AS right_price 
    FROM invoice_hearing_aids 
    LEFT JOIN invoices ON invoices.ID = invoice_hearing_aids.invoice_id 
    LEFT JOIN contacts ON contacts.id = invoices.contact_id 
    WHERE 
    trial_complete = 'Y' 
    AND invoices.company_id = '1' 
    AND invoices.date_issued >= DATE_SUB(NOW(),INTERVAL 1 YEAR) 
    AND NOT (left_price IS NULL AND right_price IS NULL)