SQL Server开发者_开发百科 2008:
I have 3 tables
Users, Scores, Lessons
Users
& Scores
are linked by StudentID
Scores
& Lessons
are linked by LessonID
I want to display the scores for a StudentID
. Here are the columns I want to display
Users.Name, Scores.LessonID, Scores.Result, Lessons.Title
I know how to Join the 2 tables. How do I throw in the 3rd table?
Same way as one table:
SELECT Users.Name, Scores.LessonID, Scores.Result, Lessons.Title
FROM Users
INNER JOIN Scores ON Users.StudentID = Scores.StudentID
INNER JOIN Lessons On Scores.LessonID = Lessons.LessonID
SELECT *
FROM T1
INNER JOIN T2
ON T2.C = T1.C
INNER JOIN T3
LEFT JOIN T4
ON T4.C = T3.C
ON T3.C = T2.C
is equivalent to (T1 Inner Join T2) Inner Join (T3 Left Join T4)
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