how to do the multivalue in mysql

[Guest_imported]

how to do the multivalue in mysql
i need to create a table student.

it has 2 attributes ssn and course_num

course_num is a multivalue attribute,, it has all the course # that student take this semester.

but how can i make it multivalue in mysql..
thanx.

 

[sleipnir214]

I would not use a multivalued column for that data. I would create a second table to store class information and a third to record the relationship between students and classes. ______________________________________________________________________
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[rycamor]

Multivalued databases are a completely different thing from SQL-based (or relational) systems. In a relational database, you would never try to place multiple values in a single column, because every column should represent a single attribute (a single fact) about it's subject. As Sleipnir said, if you have multiple values for a particular subject, then you would put those in another table, and relate that table to the main table by matching primary keys.

It is possible to place multiple values in a single SQL column, simply by making the column type TEXT of VARCHAR, and separating the values with commas (1,3,45,23), and then using your programming environment to split the data into separate values, but that is a very crude hack, and you will be sorry later, when you try to make your system portable, or more scaleable, etc... -------------------------------------------

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