Nt1310 Unit 1 Study Guide

Which of the following defines a relationship in which each occurrence of data in one entity

A relational database is a database that consists of a collection of tables with columns showing entities, and rows showing data. This type of database uses a primary key and foreign key. The foreign key in another table will point to the primary key of a table, and this is how tables can relate to each other. This permits for one-to-one, one-to-many, and many-to-many relationship between the data. An advantage of relational databases includes the ease of adding or modifying new tables and entities without needing to change the structure of the database already in place. Relational database have many features, including indexing, setting data type, and setting validation tests, all these help to ensure data integrity.

The challenging part was actually trying to understand what will be the best way to break a relation down into multiple relations without jeopardizing the integrity of the data at the same time. As I mention before it is not hard to do it but you really have to know how to do it.

Business Rules: In the entity-relationship data models, business rules must take into account all relationship models: one-to-many (1:M), one-to-one (1:1) and many-to-many (M:N). For a database on a school library, a restriction of having a student only allowed to borrow one book would need a 1:1 relationship.

When it comes to the data model, there exists a relationship that has three different representations for the reason that database requires the relationship between the tables. It goes hand-in-hand with one another without the relationship the tables would have no purpose. The information cannot be repetitive in order for the each table to work and provide the specific database that is related to the information. In different ways the tables in the Huffman Trucking Fleet Truck database

The deptNo is the unique identifier of this table known as the primary key, while the managerEmpNo is the foreign key linked to the empNo which is the primary key of the employee table.

The hierarchical typical structure has levels which shows one –to – many also relationship between a parent and children divisions. The main key this models which following by each parent can have many children as well each child has simply one parent.

The relational model organizes data into multiple tables and assigns a value to attributes in each row and column, with a unique key for each row. Other tables can use these keys to access the data without reorganizing the table.

Some records were greater certainly modeled with more than one determine in step with toddler. So, the community model accepted the modeling of many-to-many relationships in information.

In relational database management systems the tables with the specific data have relation among them that’s why the

To summarize, a database is an organized data collection or information that happens to be easily accessible, changed or updated. A DBMS is a type of software that may manage and control databases on a PC.

On the other hand it is often difficult for first time users, if the database needs to be altered when it is finished the new information could change the entire database. The World Wide Web is an example of a network database as different pages are related to each other.

1. Data inconsistency may result when updating takes place. 2. Waste of space is unavoidable.

The primary key cannot have repeating values which means the attribute may not have more than one value at a time for a given entity case is prohibited. This is known as the No Repeat Rule.

DBMS enable many users to access shared data concurrently. Concurrent access is easy if all users are only reading data. But when multiple users are accessing the database simultaneously, the database may result in inconsistencies. DBMS can prevent this occur.