Question

我有一个查询从数据库表中选择3个随机项，但我需要根据查询中字段的值对查询应用更多逻辑。

这是我迄今为止希望它有意义的东西。还没有完全测试它，但我发现我会通过你们先看看是否有任何跳出来。

SELECT ord.id, keyword, url, daily_max
  FROM orders AS ord
  LEFT JOIN product_tasks AS tsk ON tsk.id = ord.task_id
  LEFT JOIN product_groups AS grp ON grp.id = tsk.product_group
  WHERE (
    status = 'approved'  AND
    ord.total_actions_today < tsk.daily_max AND
    grp.id = 1 AND
    country_code = '$country' AND
    (   

        CASE WHEN daily_max >= 5 THEN last_displayed < (NOW() - INTERVAL 30 MINUTE)

        CASE WHEN daily_max >10 THEN last_displayed < (NOW() - INTERAVAL 5 MINUTE)

        ELSE last_displayed < (NOW() - INTERAVAL 60 MINUTE)
    )   
  )
  GROUP BY ord.id
  ORDER BY RAND()
  LIMIT 3

刚刚测试了查询，因为我怀疑我的语法有误，所以任何帮助都会受到赞赏：

＃1064 - 您的SQL语法出错;检查与您的MySQL服务器版本对应的手册，以便在'CASE WHEN daily_max＆gt;附近使用正确的语法10然后last_displayed＆lt; （现在（） - 行间5分钟）'第14行

编辑 - 修正

（经过多次尝试+编辑）：

SELECT ord.id, keyword, url, daily_max
      FROM orders AS ord
      LEFT JOIN product_tasks AS tsk ON tsk.id = ord.task_id
      LEFT JOIN product_groups AS grp ON grp.id = tsk.product_group
      WHERE (
        status = 'approved'  AND
        ord.total_actions_today < tsk.daily_max AND
        grp.id = 1 AND
        country_code = 'us'
AND  last_displayed < 
    CASE WHEN (daily_max >= 5) THEN (NOW() - INTERVAL 30 MINUTE)
         WHEN (daily_max >10) THEN (NOW() - INTERVAL 5 MINUTE)
         ELSE (NOW() - INTERVAL 60 MINUTE)
    END
    )
      GROUP BY ord.id
      ORDER BY RAND()
      LIMIT 3

http://sqlfiddle.com/#!2/ac4499/1

在where语句中解决了DOH )

Answer 1

您的WHERE结构不正确。请尝试以下方法：

SELECT ord.id, keyword, url, daily_max
  FROM orders AS ord
  LEFT JOIN product_tasks AS tsk ON tsk.id = ord.task_id
  LEFT JOIN product_groups AS grp ON grp.id = tsk.product_group
  WHERE (
    status = 'approved'  AND
    ord.total_actions_today < tsk.daily_max AND
    grp.id = 1 AND
    country_code = '$country' AND
    (   

        CASE WHEN daily_max >10 THEN (NOW() - INTERAVAL 5 MINUTE)
             WHEN daily_max >= 5 THEN (NOW() - INTERVAL 30 MINUTE)
             ELSE (NOW() - INTERAVAL 60 MINUTE)
        END > last_displayed
    )   

  )
  GROUP BY ord.id
  ORDER BY RAND()
  LIMIT 3

Answer 2

将last_displayed移出CASE，以便将其与CASE语句中预测的单个值进行比较：

WHERE...
AND  last_displayed < 
    CASE WHEN (daily_max >= 5) THEN (NOW() - INTERVAL 30 MINUTE)
         WHEN (daily_max >10) THEN (NOW() - INTERVAL 5 MINUTE)
         ELSE (NOW() - INTERVAL 60 MINUTE)
    END;

另请注意一些拼写错误 - INTERVAL而不是INTERAVAL，只需要一个CASE。

SqlFiddle here

SQL CASE在select语句中的where语句中出错

2 个答案: