Question

我有一个显示如下结果的查询：

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

如何删除左侧和价格均为空的结果。因此我不希望带有zip 54353的那个甚至出现在结果中。

以下是我查询的方式：

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

您最后可以添加HAVING子句，如下所示：

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

如果您拥有相对较少的此类不需要的记录（这样做最多可达到总结果集大小的50％），这样可以正常工作。如果有更多此类记录，那么我会更接近查询，并且很可能会修改条件。

Answer 2

请确保left_price和right_price是您可以添加条件

的列值

   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)

MYSQL查询，如果两列为null，则删除行

2 个答案: