RDBMS Relational Database Management System

field

a single characteristic of data that appears in a table as a column

SQL contraints

are the rules enforced on data columns on a table. These are used limit the type of data can go into a table. This ensures the accuracy and reliability of the data in the database.

First Rule of 1NF set basis rules

-Define the data items required, because they become the columns in a table. -Place the related data items in a table. -Ensure that there are no repeating groups of data. -Ensure that there is a primary key.

commonly used constrains in SQL

-NOT NULL Constraint − Ensures that a column cannot have a NULL value. -DEFAULT Constraint − Provides a default value for a column when none is specified. -UNIQUE Constraint − Ensures that all the values in a column are different. -PRIMARY Key − Uniquely identifies each row/record in a database table. -FOREIGN Key − Uniquely identifies a row/record in any another database table. -CHECK Constraint − The CHECK constraint ensures that all values in a column satisfy certain conditions. -INDEX − Used to create and retrieve data from the database very quickly.

Null value

A special field value, distinct from zero, blank, or any other value, that indicates that the value for the field is missing or otherwise unknown.

First Rule of 1NF

You must define data items. This means looking at the data to be stored, organizing the data into columns, defining what type each column contains and then finally putting the related

Second Rule of 1NF

ensure that are not repeating groups of data.

Third Rule of 1NF

final rule of the first normal form, create a primary key for each table which we have already created.

normatization

guidelines are divided into normal forms

What is a column?

is a vertical entity in a table that contains all information associated with a specific field in a table

what is a column

is a vertical entity in a table that contains all information associated with a specific field in a table.

record

is also called as a row of data is each individual entry that exists in a table. A record is a horizontal entity on a table.

database integrity

is the process of efficiency organizing data in a database. There are two reasons of this normalization process: -Eliminating redundant data, exam storing same data in more than one table. -Ensuring data dependencies make sense

Table

the data in an RDBMS is stored in database objects which are called