带有自定义where子句的MySQL视图子查询？答案

【问题标题】：MySQL view subquery with custom where clause?带有自定义where子句的MySQL视图子查询？
【发布时间】：2015-09-25 13:11:25
【问题描述】：

我正在尝试在 MySQL 数据库上设计一个视图，该数据库存储有关足球（足球）的信息。

我的目标是创建一个返回所有进球和得分手基本信息的视图。这是视图过去外观的简化版本：

SELECT P.Name AS Player,
       P.TeamName AS Team,
       (SELECT COUNT(*)
        FROM Goals G
        WHERE G.Scorer = P.playerID) AS TotalGoals
FROM Players P

到目前为止，一切正常。当我只想在WHERE 子句中指定的某个赛季内计算进球数时，问题就开始了，如下所示：

SELECT * FROM GoalsView WHERE Season = 1

并且它只自动返回 WHERE 子句中的赛季进球数，就好像子查询被自动编辑使其看起来像：

[...]
(SELECT COUNT(*)
FROM Goals G
WHERE G.Scorer = P.playerID
AND Season=1) AS TotalGoals
[...]

我希望我说清楚了。感谢您的帮助！

【问题讨论】：

标签： mysql view subquery

【解决方案1】：

一种可能的解决方案是

SELECT P.Name AS Player,
   P.TeamName AS Team,
   (SELECT COUNT(*)
    FROM Goals G
    WHERE G.Scorer = P.playerID AND season=1 GROUP By season) AS TotalGoals
 FROM Players P

我不知道你是否有单独的季节表或列

【讨论】：

【解决方案2】：

为了访问goals.season，您必须加入两个表：

select 
  p.name as player,
  p.teamname as team,
  count(goals.id) as totalgoals
from players p
left join goals g on g.scorer = p.playerid
group by p.name, p.teamname;

【讨论】：