Question

In one or two sentences, explain what is meant by each of the following terms when working with or designing a database. Primary key , Composite key, One-to-many relationship Data integrity

Accountin Information system

Answer 1

1. Primary Key-

A primary key is a special relational database table column (or combination of columns) designated to uniquely identify all table records.

A primary key is used as a unique identifier to quickly parse data within the database and find the relation between different tables. A relational database cannot have more than one primary key.

A primary key’s main features are:

• It must contain a unique value for each row of data.
• It cannot contain null values.
• Every row must have a primary key value.

A primary key is either an existing table column or a column that is specifically generated by the database according to a defined sequence.

2.Composite Key-

-A key that has more than one attributes is known as composite key. It is also known as compound key.

-Any key such as super key, primary key, candidate key etc. can be called composite key if it has more than one attributes.

-A composite key, in the context of relational databases, is a combination of two or more columns in a table that can be used to uniquely identify each row in the table.

3.one - to- many relatioship-

-In relational databases, a one-to-many relationship occurs when a parent record in one table can potentially reference several child records in another table. In a one-to-many relationship, the parent is not required to have child records; therefore, the one-to-many relationship allows zero child records, a single child record or multiple child records. The important thing is that the child cannot have more than one parent record.

-The opposite of a one-to-many relationship is a many-to-many relationship, in which a child record can link back to several parent records.

4. Data Integrity-

-The term data integrity refers to the accuracy and consistency of data.

-When creating databases, attention needs to be given to data integrity and how to maintain it. A good database will enforce data integrity whenever possible.

-For example, a user could accidentally try to enter a phone number into a date field. If the system enforces data integrity, it will prevent the user from making these mistakes.

-Maintaining data integrity means making sure the data remains intact and unchanged throughout its entire life cycle. This includes the capture of the data, storage, updates, transfers, backups, etc.

5.Accounting information sysytem(AIS)

An accounting information system (AIS) is a structure that a business uses to collect, store, manage, process, retrieve, and report its financial data so it can be used by accountants, consultants, business analysts, managers, chief financial officers (CFOs), auditors, regulators, and tax agencies.

-An AIS must have a database structure to store information, such as structured query language (SQL), which is a computer language commonly used for databases. SQL allows the data that's in the AIS to be manipulated and retrieved for reporting purposes. The AIS will also need various input screens for the different types of system users and data entry, as well as different output formats to meet the needs of different users and various types of information.