Questions that might be asked
You have now gone through the whole normalization process. There are several concepts you must understand and many different ways of testing you on these concepts. Below I list some questions that test you on what I consider to be the important concepts in this section.
- Look at the form in the purchase order. Draw the determinancy diagram in 1NF for this relation. Now draw the 3NF diagrams.
- Identify the transitive dependencies, partial key dependencies, determinants, candidate identifiers, primary identifier, conditional dependencies, multi-valued dependencies in this figure.
- Why isn't the relation shown in that same figure in 2NF/3NF/4NF? Identify specific examples to support your explanation.
The forest and the trees
Remember, if you do ER modeling, you're making sure that you have the “right” entities (though you may need to change some things down stream). The attributes you assign to entities will probably be pretty good. Normalization provides a check, of sorts, that the details are right. By analogy, ER ensures you haven't forgotten a kitchen in designing a house while normalization ensures that the refrigerator is not in the bathroom.