Question

为什么我得到未知专栏＆＃39; negavote＆＃39;在＆＃39; where子句＆＃39;

SELECT 
    my_users.name, 
    my_users.avatar, 
    my_users.surname, 
    fastmap_projects.*, 
    (SELECT COUNT(*) FROM `fastmap_rating` WHERE `fastmap_rating`.`map_id`=`fastmap_projects`.`id` AND `rate`='1') as `posivote`, 
    (SELECT COUNT(*) FROM `fastmap_rating` WHERE `fastmap_rating`.`map_id`=`fastmap_projects`.`id` AND `rate`='-1') as `negavote` 
FROM (`fastmap_projects`) 
    LEFT JOIN `my_users` ON `fastmap_projects`.`user_id`=`my_users`.`id` 
WHERE 
    `area_id` = '4' 
    AND (`negavote` BETWEEN -3 AND 3) 
    OR (`posivote` BETWEEN -3 AND 3)

您能否提示如何更改此功能？

Answer 1

这是您的查询，格式化（至少）我可以阅读：

SELECT my_users.name, my_users.avatar, my_users.surname, fastmap_projects.*,
       (SELECT COUNT(*)
        FROM `fastmap_rating`
        WHERE `fastmap_rating`.`map_id`=`fastmap_projects`.`id` AND `rate`='1') as `posivote`,
       (SELECT COUNT(*)
        FROM `fastmap_rating`
        WHERE `fastmap_rating`.`map_id`=`fastmap_projects`.`id` AND `rate`='-1') as `negavote`
FROM `fastmap_projects` LEFT JOIN
     `my_users`
     ON `fastmap_projects`.`user_id`=`my_users`.`id`
WHERE `area_id` = '4' AND (`negavote` BETWEEN -3 AND 3) OR (`posivote` BETWEEN -3 AND 3)

您正在尝试在where子句中使用列别名，而SQL不允许这样做（这是标准的一部分，而不是MySQL限制）。通常的解决方案是使用子查询或CTE。但是，MySQL有一个扩展名。您可以使用having子句而不是where子句：

SELECT my_users.name, my_users.avatar, my_users.surname, fastmap_projects.*,
       (SELECT COUNT(*)
        FROM `fastmap_rating`
        WHERE `fastmap_rating`.`map_id`=`fastmap_projects`.`id` AND `rate`='1') as `posivote`,
       (SELECT COUNT(*)
        FROM `fastmap_rating`
        WHERE `fastmap_rating`.`map_id`=`fastmap_projects`.`id` AND `rate`='-1') as `negavote`
FROM `fastmap_projects` LEFT JOIN
     `my_users`
     ON `fastmap_projects`.`user_id`=`my_users`.`id`
HAVING `area_id` = '4' AND (`negavote` BETWEEN -3 AND 3) OR (`posivote` BETWEEN -3 AND 3);

作为备注：只需检查您的括号，确保这是您想要做的。这将选择没有身份4的区域。你可能是这个意思：

HAVING `area_id` = '4' AND (`negavote` BETWEEN -3 AND 3 OR `posivote` BETWEEN -3 AND 3);

Answer 2

你不能在SQL where子句中使用列别名（在PostgreSQL中除外，因为那个人很流畅）

重复子选择或在子查询中包装查询并在上层查询中应用过滤器

SELECT 
    *
FROM (
  SELECT 
    my_users.NAME, 
    my_users.avatar, 
    my_users.surname, 
    fastmap_projects.*, 
    ( 
      SELECT Count(*) 
      FROM   `fastmap_rating` 
      WHERE  `fastmap_rating`.`map_id`=`fastmap_projects`.`id` 
      AND    `rate`='1'
    ) AS `posivote`, 
    ( 
      SELECT count(*) 
      FROM   `fastmap_rating` 
      WHERE  `fastmap_rating`.`map_id`=`fastmap_projects`.`id` 
      AND    `rate`='-1'
    ) AS `negavote` 
  FROM (`fastmap_projects`) 
  LEFT JOIN `my_users` ON `fastmap_projects`.`user_id`=`my_users`.`id` 
)
WHERE `area_id` = '4' 
AND (`negavote` BETWEEN -3 AND 3) 
OR (`posivote` BETWEEN -3 AND 3)

Sql Subselect计数为count相等的位置

2 个答案: