Thanks Jason for a very clear explanation.
in a mysql database, all of your tables will have a primary key column.for the classes table, there will be a primary key column that uniquely identifies the class.
for the student table, there will be an ID column that uniquely identifies the student.
In MySQL you use these ID values to create relationships between the data.
In my class table I have 3 primary keys ... those are (PKsecSectionCode, PKsecSectionSchoolYear,PKsecSectionSemester) because in every school year and semester the SECTION CODE of the class is repeating. for example (the section code is:M001, SY is 2011-2012, let say the semester is 1st Semester) ...
and when the 1st Semester is already finished,.. there is a 2nd semester so (SECTION CODE is M001, SY is 2011-2012, SEMESTER IS "SECOND SEMESTER")
So to avoid the duplication of the Row I used multiple PRIMARY KEYS of the my Class table.
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1.) Is my class table structure for my database is correct ? because this is my first time to used the MULTIPLE PRIMARY KEY in a table.
2.) Now I want to join this MULTIPLE PRIMARY KEY table to other tables ... can you help give me some PATTERNS AND HINTS in JOINING A TABLE (already have the relationship of my tables)
...
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THANKS IN ADVANCED ... :)
