Mysql 我想把CourseName像(4,2,5)一样数在“中”;课程数目“;列,但输出显示为完整的courseName
我想显示教员的全名以及他们目前正在教授的课程数量 我的问题是:Mysql 我想把CourseName像(4,2,5)一样数在“中”;课程数目“;列,但输出显示为完整的courseName,mysql,oracle,Mysql,Oracle,我想显示教员的全名以及他们目前正在教授的课程数量 我的问题是: SELECT CONCAT( FName, ' ', LName ) AS "Faculty Names", course.CourseName AS 'NUmbers Of Courses' FROM Faculty LEFT JOIN course ON (course.FacultyID = faculty.FacultyID) ORDER BY faculty.FacultyID` 问题1:我想在“课程数”列中计算课程名
SELECT CONCAT( FName, ' ', LName ) AS "Faculty Names", course.CourseName AS 'NUmbers Of Courses'
FROM Faculty LEFT JOIN course ON (course.FacultyID = faculty.FacultyID)
ORDER BY faculty.FacultyID`
问题1:我想在“课程数”列中计算课程名称,如(4,2,5),但显示的输出是完整的课程名称
问题2:在“课程数”列中使用左连接,有些行有空值,但我想在那里显示0
您需要一个
分组依据
和计数
。检查这个-
SELECT CONCAT( FName, ' ', LName ) AS "Faculty Names",
COUNT(course.CourseName) AS 'NUmbers Of Courses', faculty.FacultyID
FROM Faculty
LEFT JOIN course ON (course.FacultyID = faculty.FacultyID)
GROUP BY faculty.FacultyID, "Faculty Names"
ORDER BY faculty.FacultyID
注意:在按分组时,您应该包括FacultyID,因为您永远无法确保任何两个facults都不会有相同的FName
+LName