Adding Additional Tables to an Existing Query

Question

Dear All
I have the following tables and relationships:
I have the following query that returns records from the table SENAlert where the StudentID and the TeacherUsername are passed in as parameters.
Also, records are only returned if there isn’t a corresponding record in the SENAlertHistory table (i.e. SENAlertHistorySENAlertID IS NULL).
This query is returning the results that I would expect:
SELECT       
SENAlert.SENAlertID, SENAlertType.SENAlertTypeDescription
FROM           
SENAlertHistory RIGHT OUTER JOIN
Teacher INNER JOIN
Class ON Teacher.TeacherCode = Class.ClassTeacherCode INNER JOIN
ClassMember INNER JOIN
SENAlert INNER JOIN
SENAlertType ON SENAlert.SENAlertType = SENAlertType.SENAlertTypeID INNER JOIN
Student ON SENAlert.SENAlertStudentID = Student.StudentID ON ClassMember.ClassMemberStudentID = Student.StudentID ON
Class.ClassClassCode = ClassMember.ClassMemberClassCode ON SENAlertHistory.SENAlertHistorySENAlertID = SENAlert.SENAlertID AND
SENAlertHistory.SENAlertHistoryTeacherCode = Teacher.TeacherCode
WHERE       
(Student.StudentID = 011763) AND (Teacher.TeacherUsername = 'dsmith') AND (SENAlertHistory.SENAlertHistorySENAlertID IS NULL)
However, I need to extend this query to include additional teachers who may also teach this student. I am trying to add in 3 additional copies of
the Teacher table as Teacher_1, Teacher_3 and Teacher _3 in order to include them in the query also.
However, when I add these tables in I no longer get any results returned.
I have managed to do this on other queries but not this one.
SELECT SENAlert.SENAlertID, SENAlertType.SENAlertTypeDescription
FROM SENAlertHistory INNER JOIN
Teacher ON SENAlertHistory.SENAlertHistoryTeacherCode = Teacher.TeacherCode INNER JOIN
Teacher AS Teacher_1 ON SENAlertHistory.SENAlertHistoryTeacherCode = Teacher_1.TeacherCode INNER JOIN
Teacher AS Teacher_2 ON SENAlertHistory.SENAlertHistoryTeacherCode = Teacher_2.TeacherCode INNER JOIN
Teacher AS Teacher_3 ON SENAlertHistory.SENAlertHistoryTeacherCode = Teacher_3.TeacherCode RIGHT OUTER JOIN
Class INNER JOIN
ClassMember INNER JOIN
SENAlert INNER JOIN
SENAlertType ON SENAlert.SENAlertType = SENAlertType.SENAlertTypeID INNER JOIN
Student ON SENAlert.SENAlertStudentID = Student.StudentID ON ClassMember.ClassMemberStudentID = Student.StudentID ON
Class.ClassClassCode = ClassMember.ClassMemberClassCode ON Teacher_3.TeacherCode = Class.ClassTeacherCode AND
Teacher_2.TeacherCode = Class.ClassTeacherCode AND Teacher_1.TeacherCode = Class.ClassTeacherCode AND
Teacher.TeacherCode = Class.ClassTeacherCode AND SENAlertHistory.SENAlertHistorySENAlertID = SENAlert.SENAlertID
WHERE (Student.StudentID = 011763) AND (SENAlertHistory.SENAlertHistorySENAlertID IS NULL)
AND (Teacher.TeacherUsername = 'admin\dsmith' OR Teacher_1.TeacherUsername = 'admin\dsmith' OR Teacher_2.TeacherUsername = 'admin\dsmith' OR Teacher_3.TeacherUsername = 'admin\dsmith')
No results are returned from this adapted query. I have noticed that by adding the additional tables, it keeps changing the type of joins that I
have between certain tables. I have tried all sorts of combinations but haven't been able to make it work.
I would be really grateful for any advice that you may be able to offer.
Many thanks
Daniel

Answer 1

Dear All
I followed the advice and created the query again from scratch, one table and relationship at a time checking that I am getting the expected result. I have put much of the query back together with the correct output:
SELECT
SENAlert.SENAlertID,
SENAlertType.SENAlertTypeDescription
FROM dbo.SENAlert
INNER JOIN dbo.SENAlertType
ON SENAlert.SENAlertType = SENAlertType.SENAlertTypeID
INNER JOIN dbo.Student
ON SENAlert.SENAlertStudentID = Student.StudentID
INNER JOIN dbo.ClassMember
ON ClassMember.ClassMemberStudentID = Student.StudentID
INNER JOIN dbo.Class
ON ClassMember.ClassMemberClassCode = Class.ClassClassCode
INNER JOIN dbo.Teacher
ON Class.ClassTeacherCode = Teacher.TeacherCode
LEFT OUTER JOIN dbo.Teacher AdditionalTeacher1
ON AdditionalTeacher1.TeacherCode = Class.ClassAdditionalTeacherCode1
LEFT OUTER JOIN dbo.Teacher AdditionalTeacher2
ON AdditionalTeacher2.TeacherCode = Class.ClassAdditionalTeacherCode2
LEFT OUTER JOIN dbo.Teacher AdditionalTeacher3
ON AdditionalTeacher3.TeacherCode = Class.ClassAdditionalTeacherCode3
WHERE Student.StudentID = 011763
AND (Teacher.TeacherUsername = 'admin\dsmith'
OR AdditionalTeacher1.TeacherUsername = 'admin\dsmith'
OR AdditionalTeacher2.TeacherUsername = 'admin\dsmith'
OR AdditionalTeacher3.TeacherUsername = 'admin\dsmith')
The problem arises when I try to add the SENAlertHistory table back in. I only want to show results where a related record does not exist in SENAlertHistory. I have tried every combination of relationship but none have been successful.
I think maybe I need to be using a subquery instead.
Thanks for your help
Daniel
do you mean this?
SELECT
SENAlert.SENAlertID,
SENAlertType.SENAlertTypeDescription
FROM dbo.SENAlert
INNER JOIN dbo.SENAlertType
ON SENAlert.SENAlertType = SENAlertType.SENAlertTypeID
INNER JOIN dbo.Student
ON SENAlert.SENAlertStudentID = Student.StudentID
INNER JOIN dbo.ClassMember
ON ClassMember.ClassMemberStudentID = Student.StudentID
INNER JOIN dbo.Class
ON ClassMember.ClassMemberClassCode = Class.ClassClassCode
INNER JOIN dbo.Teacher
ON Class.ClassTeacherCode = Teacher.TeacherCode
AND NOT EXISTS ( SELECT 1
FROM SENAlertHistory
WHERE SENALertHistoryTeacherCode = Teacher.TeacherCode
AND SENAlertHistorySENAlertID = SENAlert.SENAlertID)LEFT OUTER JOIN dbo.Teacher AdditionalTeacher1
ON AdditionalTeacher1.TeacherCode = Class.ClassAdditionalTeacherCode1
AND NOT EXISTS (SELECT 1
FROM SENAlertHistory
WHERE SENAlertHistoryTeacherCode = AdditionalTeacher1.TeacherCode
AND SENAlertHistorySENAlertID = SENAlert.SENAlertID
LEFT OUTER JOIN dbo.Teacher AdditionalTeacher2
ON AdditionalTeacher2.TeacherCode = Class.ClassAdditionalTeacherCode2
AND NOT EXISTS (SELECT 1
FROM SENAlertHistory
WHERE SENAlertHistoryTeacherCode = AdditionalTeacher2.TeacherCode
AND SENAlertHistorySENAlertID = SENAlert.SENAlertID
LEFT OUTER JOIN dbo.Teacher AdditionalTeacher3
ON AdditionalTeacher3.TeacherCode = Class.ClassAdditionalTeacherCode3
AND NOT EXISTS (SELECT 1
FROM SENAlertHistory
WHERE SENAlertHistoryTeacherCode = AdditionalTeacher3.TeacherCode
AND SENAlertHistorySENAlertID = SENAlert.SENAlertID
WHERE Student.StudentID = 011763
AND (Teacher.TeacherUsername = 'admin\dsmith'
OR AdditionalTeacher1.TeacherUsername = 'admin\dsmith'
OR AdditionalTeacher2.TeacherUsername = 'admin\dsmith'
OR AdditionalTeacher3.TeacherUsername = 'admin\dsmith')
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