5/6/2021 0 Comments Third Normal Form Example
Sure, in most cases it would be, but to avoid duplication we should add a primary key.Its commonly done by database developers and database administrators.This means that normalization in a DBMS (Database Management System) can be done in Oracle, Microsoft SQL Server, MySQL, PostgreSQL and any other type of database.
Without normalization on a database, the data can be slow, incorrect, and messy. We would have to query all of the columns that could have this Class field and rename each one that was found. Each of these rules transforms the data to a certain structure, called a normal form. The third rule is then applied and the data is in third normal form. Ive written a post on designing a database, but lets see what is involved in getting to each of the normal forms in more detail. Normalization in DBMS starts with the first rule being applied you need to apply the first rule before applying any other rules. In this case, were going to use a student and teacher database at a school. We mentioned this earlier in the article when we spoke about anomalies, but here it is again. This is called a primary key, and is a database term for a field that is unique to a single row. ![]() I prefer using the ID suffix, so I would call it student ID. The table name is written, and all of the columns are shown in brackets, with the primary key underlined. So if youre looking for one to use, take a look at that list. It also means that each field that is not the primary key is determined by that primary key, so it is specific to that record. Some fields are dependent on the student ID, and others are not. It is not dependent on the student, as more than one student can have a subject, and the subject isnt a part of the definition of a student. When we are writing queries on this table or looking at diagrams, its clearer what subject name is instead of using subject. Two subjects could have the same name and this would cause problems in our data. Ill call this subject ID, to be consistent with the student ID. We can do this for all four of our subject columns in the student table, removing them from the student table so it looks like this. The teacher is separate to the student so should be captured separately.
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