这是检索课程数据的原始SQL语句:
SELECT
`courses`.`id` AS `id`,
`courses`.`title` AS `title`,
`courses`.`description` AS `description`,
MATCH (coursedata.title) AGAINST ('Salsa') * 5 + MATCH (coursedata.description) AGAINST ('Salsa') * 2 AS `relevance`,
GROUP_CONCAT(trainers.name SEPARATOR '|||') AS `trainers`
FROM `courses`
INNER JOIN `coursedata` ON `courses`.`id` = `coursedata`.`id`
INNER JOIN `courses_trainers` ON `courses`.`id` = `courses_trainers`.`course_id`
INNER JOIN `trainers` ON `trainer_id` = `trainers`.`id`
GROUP BY `courses`.`id`
HAVING `relevance` >= '3'
由于它使用MySQL Extensions to GROUP BY
并且无法执行,如果sql_mode
设置为ONLY_FULL_GROUP_BY
,我必须使其符合标准SQL:
SELECT * FROM (
SELECT
`courses`.`id` AS `id`,
`courses`.`title` AS `title`,
`courses`.`description` AS `description`,
MATCH (coursedata.title) AGAINST ('Salsa') * 5 + MATCH (coursedata.description) AGAINST ('Salsa') * 2 AS `relevance`
-- , GROUP_CONCAT(trainers.name SEPARATOR '|||') AS `trainers`
FROM `courses`
INNER JOIN `coursedata` ON `courses`.`id` = `coursedata`.`id`
LEFT JOIN `courses_trainers` ON `courses`.`id` = `courses_trainers`.`course_id`
LEFT JOIN `trainers` ON `trainer_id` = `trainers`.`id`
) AS subselect
WHERE `relevance` >= '3'
这个很好,但我不能再使用GROUP_CONCAT
函数(为了将多个trainer
字段连接到一个字段/字符串)。
Error Code: 1064
You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near 'GROUP_CONCAT(trainers.name SEPARATOR '|||') AS `trainers`
FROM `courses`
INNER' at line 7
是否有其他方法可以使用GROUP_CONCAT
功能?