what is database normalization
Normally used database normalizations:
First Normal Form (1NF)
Second Normal Form (2NF)
Third Normal Form (3NF)
First normal form defines that there is primary key and there is no repeating groups and what is required in a table.
second normal form:
It defines that all rules are met what are in first normal form and there is no partial dependency
in any of the columns on the primary key.
third normal form :
it is rule of thumb what is required in first and second normal form .
It also defines that all non-primary fields depdends on primary key.
what are sql constraints:
Provides a default value for a column when none is specified.
Ensures that all values in a column are different.
Use to create and retrieve data from the database very quickly.
Uniquely identified each rows/records in a database table.
Uniquely identified a rows/records in any another database table.
The CHECK constraint ensures that all values in a column satisfy certain conditions.
NOT NULL Constraint:
Ensures that a column cannot have NULL value.
The standard SQL commands to interact with relational databases are CREATE, SELECT, INSERT, UPDATE, DELETE and DROP.
They are called data definition language.
Creates a new table, a view of a table, or other object in database
Modifies an existing database object, such as a table.
Deletes an entire table, a view of a table or other object in the database.
data manipulation language:
Creates a record
It deletes records
It updates the records.
what is data control language:
It gives a privilege to user.
It takes privilege from user.
What is data query language:
It retrieves what specified records from specified tables.
what is rdbms.
It stands for relational database management system.It works for all microsoft access,