Mysql 按日期分组的嵌套Select查询

我有一个名为“rawTweets”的表，如下所示

tweet, date, id, username, compoundScore

我想计算某些关键字的平均值，并按日期对结果进行分组，但我还是有点像sql“新手”。在我的脑海里，它看起来像下面这样

需要一点指导-谢谢

SELECT
    `date`,
    AVG(
        SELECT compoundScore 
        FROM rawTweets 
        WHERE tweet LIKE '%trump%'
    ) AS Trump,
    AVG(
        SELECT compoundScore 
        FROM rawTweets 
        WHERE tweet LIKE '%chaffetz%'
    ) as Chaffetz
FROM rawTweets 
WHERE 
    compoundScore <> 0.0 
    AND compoundScore IS NOT NULL
GROUP BY `date`;

您可以尝试以下方法，而不是使用嵌套选择：

SELECT
    `date`,
    AVG(COALESCE(rt2.compoundScore, 0)) AS Trump,
    AVG(COALESCE(rt3.compoundScore, 0)) AS Chaffetz
FROM 
    rawTweets rt
    -- Trump
    LEFT JOIN rawTweets rt2 ON
        rt2.id = rt.id
        AND rt2.tweet LIKE '%trump%'
    -- Chaffetz
    LEFT JOIN rawTweets rt3 ON
        rt3.id = rt.id
        AND rt3.tweet LIKE '%chaffetz%'
WHERE
    compoundScore <> 0.0
    AND compoundScore IS NOT NULL
GROUP BY `date`;  

执行此操作时，您可以使用avg和case：

select date
  ,avg(case when tweet like '%trump%' then compoundScore else null end) as Trump
  ,avg(case when tweet like '%chaffetz%' then compoundScore else null end) as Chaffetz
from rawTweets
where compoundScore <> 0.0 and compoundScore is not null
group by date