MySQL 找不到列

Question

您好，他的查询给了我以下错误:

“on 子句”中存在未知列“m.home_team_id”

SELECT DISTINCT (
`m`.`match_id`), 
`m`.`competition_id`, 
`m`.`date`, 
`h`.`team_name` AS "homeTeam", `h`.`team_id` AS "homeTeamID", 
`a`.`team_name` AS "awayTeam", `a`.`team_id` AS "awayTeamID", 
`o`.`for`, `o`.`against` 
FROM `single` bs, `matches` m, `teams` t, `outcomes` o 
JOIN `teams` `h` ON `m`.`home_team_id`=`h`.`team_id` 
JOIN `teams` `a` ON `m`.`away_team_id`=`a`.`team_id` 
WHERE `bs`.`match_id`=`m`.`match_id` 
AND `m`.`score_id`=`o`.`outcome_id` 
AND `actual_return` IS NOT NULL`enter code here`

m 是名为 matches 的表的别名，该表具有列 home_team_id 和 away_team_id 所以我不明白为什么该列不能'找不到吗？

艾伦。

Answer 1

SELECT 
     DISTINCT (`m`.`match_id`), 
      `m`.`competition_id`, 
      `m`.`date`, 

      `h`.`team_name` AS "homeTeam",
      `h`.`team_id` AS "homeTeamID", 

      `a`.`team_name` AS "awayTeam",
      `a`.`team_id` AS "awayTeamID", 

      `o`.`for`, 
      `o`.`against` 

FROM `single` bs

      join `matches` m ON bs.match_id = m.match_id
      join `outcomes` o m.score_id = o.outcome_id 
      join `teams` t   --<--- I don't know what the join is for `teams` here 
                          --- you probably don't need this in the query at all 

      JOIN `teams` `h` ON `m`.`home_team_id`=`h`.`team_id` 
      JOIN `teams` `a` ON `m`.`away_team_id`=`a`.`team_id` 

WHERE  `actual_return` IS NOT NULL