Database Designing
There are some rules are available for designing the
database. These are given below :
- MySQL use the alpha numeric character .
- MySQL limited the 64 characters .
- MySQL use the underscore (_) to separate word.
- MySQL is entirely lowercase word .
- MySQL use the plural table name to indicate multiple value store and
singular column names .
MySQL Database Normalization
Normalization is a process that is used in relational database design to organize the data for minimizing the duplication. In normalization, we divide the database in two or more tables and create the relationship between them. After isolate the data we performed some additions, deletions or modifications of a field on only one table, then that can be propagated on the rest of the database through the defined relationships.
The main two goals of normalization process are: eliminate the redundancy of data and make sure that the data dependencies (relationship) make sense. By these two goals we can reduce the space that is consumed by the database and ensure that data is logically stored.
First normal Form
The First Normal Form requires the atomic values in each column. Atomic means the set of values
are not available with in the column. In other words, in First Normal Form table must have at least one
candidate key and make sure the table don’t have any duplicate record. In
First Normal Form repeating groups are not allowed, that is no attributes which
occur a different number of times on different records
Second normal Form
You can achieve the Second Normal Form only then
when your table must meet the First Normal Form with its entire requirement. As
you seen the First Normal Form works with only atomicity of data, but Second
Normal Form deals with the relationships of tables between composite keys and
non-key columns. In Second Normal Form subset of data is removed, and its apply
to multiple rows of a table and then place them in separate tables.
Third Normal Form
You can achieve the Third Normal Form only then when your table must meet the Second
Normal Form with its entire requirement. In Third Normal Form, all columns must be directly depended on the primary key means remove the column, which is not dependent upon the primary key.
Boyce - Codd Normal Form
You can achieve the Boyce - Codd Normal Form only then when your table must meet the
Third Normal Form with its entire requirement. In Boyce - Codd Normal Form every non-trivial functional dependency must be a dependency on a superkey.
Fourth Normal Form
You can achieve the Fourth Normal Form only then when your table must meet the Boyce - Codd Normal Form with its entire requirement. Fourth Normal Form confirmed you that the independent multivalued facts are efficiently and correctly represented in database design.
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