We need to know all the FDs (functional dependencies) that hold to determine CKs (candidate keys), not just those in some list. Look at a (correct & general) definition of CK or algorithm for finding CKs (in a published textbook, not a youtube video). Is your list appropriately a closure (all the FDs that hold) … Read more
Normalization is basically to design a database schema such that duplicate and redundant data is avoided. If the same information is repeated in multiple places in the database, there is the risk that it is updated in one place but not the other, leading to data corruption. There is a number of normalization levels from … Read more
A relation has an associated set of columns of any type and an associated set of rows. There is one value per column per row. Sometimes “normalize” is used to mean (1) “decompose each relation to smaller relations that are its projections and that join back to it”. This is normalization to higher NFs (normal … Read more
In addition to violating First Normal Form because of the repeating group of values stored in a single column, comma-separated lists have a lot of other more practical problems: Can’t ensure that each value is the right data type: no way to prevent 1,2,3,banana,5 Can’t use foreign key constraints to link values to a lookup … Read more