Question

SELECT `location`.`building`, `location`.`classroom` FROM `schools`
LEFT OUTER JOIN `location` 
ON `location`.`location_serial` = `classroom`.`location_serial` 
LEFT OUTER JOIN `rack_info` 
ON `classroom_info`.`location_serial` = `classroom`.`location_serial` 
WHERE (
    (((`location`.`building` LIKE 'SCH%')))
    AND 
    (`classroom_info`.`status` NOT IN (1, 2))
    AND 
    (
        (
            (`location`.`building` = 'SCH1' AND `location`.`classroom` != '99')
            AND
            (`location`.`building` = 'SCH1' AND `location`.`classroom` != '34')
        )
    )
)

我的WHERE子句有问题。

比方说location.building可以是SCH1，SCH2，SCH3，SCH4，CAB1，CAB2。我正在尝试选择所有SCH教室，其中某些教室状态为1和2。

一切正常

当我尝试进一步过滤结果以排除建筑物为SCH1且教室ID为99，建筑物为SCH1且教室ID为34的实例时，就会出现问题。我想显示所有其他教室所有SCH建筑物（包括SCH1，例如SCH1.98），但不包括上面的SQL查询中提到的两个特定教室（SCH1.99和SCH1.34）

我可能还想排除其他SCH房间，例如SCH2.24，SCH3.33-但我希望所有其他教室都出现。

我一直在找几个小时，我想我已经达到了我的能力极限-欢迎大家光临。

Answer 1

以下是我编写WHERE子句的一些方法：

WHERE location.building LIKE 'SCH%'
  AND classroom_info.status NOT IN (1, 2)
  AND NOT (location.building = 'SCH1' AND location.classroom = '99')
  AND NOT (location.building = 'SCH1' AND location.classroom = '34')


WHERE location.building LIKE 'SCH%'
  AND classroom_info.status NOT IN (1, 2)
  AND NOT (location.building = 'SCH1' AND location.classroom IN ('99', '34'))


WHERE location.building LIKE 'SCH%'
  AND classroom_info.status NOT IN (1, 2)
  AND (location.building, location.classroom) NOT IN (
      ('SCH1', '99'),
      ('SCH1', '34')
  )

这使得添加更多排除案例非常简单。

Answer 2

条件：

排除建筑物为SCH1且教室ID为99的实例

可以写为：

NOT (`location`.`building` = 'SCH1' AND `location`.`classroom` = '99')

或：

(`location`.`building` <> 'SCH1' OR `location`.`classroom` <> '99')

这样做：

SELECT `location`.`building`, `location`.`classroom` FROM `schools`
LEFT OUTER JOIN `location` 
ON `location`.`location_serial` = `classroom`.`location_serial` 
LEFT OUTER JOIN `rack_info` 
ON `classroom_info`.`location_serial` = `classroom`.`location_serial` 
WHERE
    `location`.`building` LIKE 'SCH%'
    AND 
    `classroom_info`.`status` NOT IN (1, 2)
    AND 
    (`location`.`building` <> 'SCH1' OR `location`.`classroom` <> '99')
    AND
    (`location`.`building` <> 'SCH1' OR `location`.`classroom` <> '34')

Answer 3

要“排除建筑物为SCH1且教室ID为99，而建筑物为SCH1且教室ID为34的实例”，则可以检查建筑物不是'SCH1'或（尤其是在建筑物是'SCH1'），教室ID不在'34'或'99'中。（假设教室ID为varchar，否则您可以删除单引号。）

SELECT `location`.`building`,
       `location`.`classroom`
       FROM `schools`
            LEFT OUTER JOIN `location` 
                            ON `location`.`location_serial` = `classroom`.`location_serial` 
            LEFT OUTER JOIN `rack_info` 
                            ON `classroom_info`.`location_serial` = `classroom`.`location_serial` 
       WHERE `location`.`building` LIKE 'SCH%'
             AND `classroom_info`.`status` NOT IN (1,
                                                   2)
             AND (`location`.`building` <> 'SCH1'
                   OR `location`.`classroom` NOT IN ('34',
                                                     '99'));

MySQL where子句问题

3 个答案: