如果它们存在于第二个 MySQL 查询中，如何从第一个 MySQL 查询中删除结果？

Question

如何从第一个查询中删除结果，如果它们存在于第二个查询中？

我查看了以前的 stackoverflow 线程，但仍然无法正常工作。

到目前为止，我的MySQL 查询如下：

SELECT roomL.CityCode, roomL.TableCode
FROM (SELECT roomL.CityCode, roomL.TableCode 
      FROM roomL
      WHERE roomL.StatusEnum = 1 
      AND roomL.TableCode NOT IN (select stock.TableCode from stock)
      AND roomL.TimeSeen BETWEEN 10/10/2014 AND Now())

WHERE NOT EXISTS (SELECT roomL.CityCode , roomL.TableCode 
                  FROM roomL
                  WHERE roomL.StatusEnum = 1 
                  AND roomL.TableCode NOT IN (select stock.TableCode from stock)
                  AND roomL.TimeSeen BETWEEN DATE_ADD( 17/10/2014 ,INTERVAL 1 DAY) AND Now())

目前我收到错误：

SQL 错误 (1248)：每个派生表都必须有自己的别名

Answer 1

试试这个：

SELECT temp1.CityCode, temp1.TableCode
FROM (SELECT roomL.CityCode, roomL.TableCode 
      FROM roomL
      WHERE roomL.StatusEnum = 1 
      AND roomL.TableCode NOT IN (select stock.TableCode from stock)
      AND roomL.TimeSeen BETWEEN '2014-10-10' AND Now())temp1

left join (SELECT roomL.CityCode , roomL.TableCode 
                  FROM roomL
                  WHERE roomL.StatusEnum = 1 
                  AND roomL.TableCode NOT IN (select stock.TableCode from stock)
                  AND roomL.TimeSeen BETWEEN DATE_ADD( '2014-10-17' ,INTERVAL 1 DAY) AND Now())temp2 
ON temp1.CityCode=temp2.CityCode AND temp1.TableCode=temp2.TableCode
WHERE temp2.CityCode IS NULL AND temp2.TableCode IS NULL;

Answer 2

首先使用正确的数据类型更改表，您需要先添加额外的列：

ALTER table roomL
ADD COLUMN TimeSeen1 DATE;

第二次更新来自字符串 im TimeSeen 的新列

UPDATE roomL
SET TimeSeen1 = STR_TO_DATE(TimeSeen, '%d/%m/%Y');

第三次删除旧列

ALTER TABLE roomL
DROP COLUMN TimeSeen;

最后重命名新列（可选）

ALTER TABLE roomL
CHANGE COLUMN TimeSeen1 TimeSeen DATE;

然后稍微调整一下就可以使用草莓的查询了：

SELECT
     r.CityCode,
     r.TableCode
FROM
    roomL r
LEFT JOIN
    stock s
    ON r.TableCode = s.TableCode
WHERE
    r.Status_Enum = 1 AND
    r.TimeSeen BETWEEN '2014-10-10' AND '2014-10-18'
    AND s.TableCode IS NULL