Question

我有2个select语句从同一个人的2个表中提取数据。我知道他们可以通过连接组合，但我无法让语法为我工作。

查询1：

SELECT SUBSTRING_INDEX(username,'@',1) AS username, 
COUNT(username) as count,
ROUND(
SUM(
CONVERT(SUBSTRING(contribution_score, -2), UNSIGNED INTEGER)  +
CONVERT(SUBSTRING(focused_score, -2), UNSIGNED INTEGER)  +
CONVERT(SUBSTRING(prepared_score, -2), UNSIGNED INTEGER) + 
CONVERT(SUBSTRING(work_score, -2), UNSIGNED INTEGER)  
)/COUNT(username)/76*100)
as average

FROM project_rubrics
GROUP BY username
LIMIT 0, 90

查询2：

SELECT username,COUNT(username) as days FROM logon GROUP BY username

常用链接是用户名字段我想要一个结果集，它给出了每个学生的用户名，天数和平均值，但我无法获得联接或组合选择。

感谢任何帮助。

Answer 1

你可以做一个子查询。

SELECT SUBSTRING_INDEX(username,'@',1) AS username, 
COUNT(username) as count,
ROUND(
SUM(
CONVERT(SUBSTRING(contribution_score, -2), UNSIGNED INTEGER)  +
CONVERT(SUBSTRING(focused_score, -2), UNSIGNED INTEGER)  +
CONVERT(SUBSTRING(prepared_score, -2), UNSIGNED INTEGER) + 
CONVERT(SUBSTRING(work_score, -2), UNSIGNED INTEGER)  
)/COUNT(username)/76*100)
as average,

(SELECT COUNT(username) as days FROM logon WHERE logon.username=project_rubrics.username GROUP BY username) as username_count

FROM project_rubrics
GROUP BY username
LIMIT 0, 90

mysql结合了多个select语句结果

1 个答案: