Sql normalization tutorial pdf

To convert it in to first normal form user need to consider following things. The automic values are nothing but the single value in single cell. The record in table should be unique. Each and every record should be unique. There should not be no repeating group. To normalize the above table in First normal form we need to convert that table in to two different tables.

The second step is to convert the table in to second normal form. Before converting the table in to second normal form in SQL normalization Let us check the following table which is in First Normal Form. There should not be any partial dependency of any column on primary key. Means the table have concatanated primary key and each attribute in table depends on that concatanated primary key. All Non-key attributes are fully functionally dependent on primary key.

If primary is is not composite key then all non key attributes are fully functionally dependent on primary key. These tables are created in Second normal form. In next section i would like to give you the examples with third normal form. In this section i would like to give you the Third Normal Form.

The following are most important points needs to be considered in normalization. When table 1 is Functionally dependent on table 2. And Salary Slip no Determines Employee name. Therefore Employee No determines Employee Name. We have transitive functional dependency so that this structure not satisfying Third Normal Form.

For That we will Split tables into following 2 tables to convert the table in to third normal form :. Amount of data duplication is removed because transitive dependency is removed in third normal form. BCNF Normal form is higher version of third normal form.

This form is used to handle analomies which are not handled in third normal form. BCNF does not allow dependencies between attributes that belongs to candidate keys. It drops restriction of the non key attributes from third normal form. These are some most important SQL Normalization examples with its explanation. These normalization techniques are used in SQL to convert simple table in to normalized form.

That is a composite key. We have divided our 1NF table into two tables viz. Table 1 and Table2. Table 1 contains member information. Table 2 contains information on movies rented. Records can be uniquely identified in Table 1 using membership id. You will only be able to insert values into your foreign key that exist in the unique key in the parent table.

This helps in referential integrity. The above problem can be overcome by declaring membership id from Table2 as foreign key of membership id from Table1.

Now, if somebody tries to insert a value in the membership id field that does not exist in the parent table, an error will be shown! A transitive functional dependency is when changing a non-key column, might cause any of the other non-key columns to change. Now our little example is at a level that cannot further be decomposed to attain higher normal form types of normalization in DBMS. In fact, it is already in higher normalization forms.

Separate efforts for moving into next levels of normalizing data are normally needed in complex databases. However, we will be discussing next levels of normalisation in DBMS in brief in the following. Even when a database is in 3 rd Normal Form, still there would be anomalies resulted if it has more than one Candidate Key.

If no database table instance contains two or more, independent and multivalued data describing the relevant entity, then it is in 4 th Normal Form. A table is in 5 th Normal Form only if it is in 4NF and it cannot be decomposed into any number of smaller tables without loss of data.

Skip to content. What is Normalization? Database Normalization With Examples Database Normalization Example can be easily understood with the help of a case study. We have again divided our tables and created a new table which stores Salutations. Sometimes is BCNF is also referred as 3. Report a Bug. Previous Prev. Next Continue.