Database Concepts and Structures Assignment Help
Database Concepts and Structures: The Elements That Make Up a Database
What is Data?
Data are basic facts and values which can be either character or number and the combination of both. The task carry out by any system it carry out the data in some way. User play with the data and without data our systems are not of any use. List of the data are unorganized so there are various method and advanced technology invented by researchers to make the scattered data organized and access it more efficiently. Data is different from programs which is a set of instructions that deal to execute the task for the computer to perform.
What is Database?
As we know database is an organized collection of data so it provide structure to organize the data instead of an unordered list of data. So database provide one of the most common structure of tables i.e. Database tables which consist of rows and columns, rows are aligned horizontally and columns are aligned vertically. We can say table as a Two-dimensional array consist of data that are organized in rows and columns. There are some other terminologies that make a structured database. A record is a single row data that determine the details about a particular thing so a database table is a collection of records that sometimes also known as entity or object. A field is a column in the table which represent a single value for each record, in other words it also termed as attributes. So we can say a record is a collection of related attributes that make a single database entry.
Elements of Database
Database Schema
Schema are stored in the data dictionary and defined in the text database language. We can say schema is a graphical depiction of the data structure. Schema define the tables and the field in each table and associated relationships between both the two. Schema is mainly of three types: Physical, logical and view schema. In physical schema data is stored in blocks of storage, and logical schema determine the design of database at logical level. View Schema determine the design of the database at view level which describe the interaction of end users with the database.
Columns in Database
We can define column as a set of data values, and the value must be of single type in a table. In database columns are from top to bottom and contain complex data like images, whole documents, video clip also. One of the goal of column representation database is to efficiently read and write data to and from hard disk to speed up the time taken to return the result of the applied query.
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Rows in Database
Row is also another data record within the table which specify the complete information of the particular record. It is sometimes also known as tuples. Rows values are aligned horizontal within a table which contain multiple field that are defined by column. Row is different from record, because record is considered as each row in a table to a specific person or employee. So we can say a row contain multiple columns in database.
Data Types in Database
Data type define the type of data that are going to be stored in the database which is mainly of three types Alphanumeric, Numeric and data and Time. Alphanumeric data types contain values like character, numbers, special characters or the combination of any two. Arithmetic functions performed by using numeric value cannot stored in alphanumeric field. Whereas numeric data type are used to store numeric data and Data and Time are used to store date and time values.
Keys in Database
Keys in database plays a vital role in the structure of a table. Keys are used to ensure each record in the table can be uniquely identified by one or a combination of fields within the table. This will help to ensure integrity and also help to identify relation between them. There are many types of keys but we are going to discuss the major one that help to design a structured database.
Types of keys
- Primary key: This key uniquely identify each record in the table. By using this key will ensure uniqueness and no data redundancy means no duplicate value allowed to be entered. Once you set a record as a primary key then access forces you to enter the value in that place you cannot left that place empty. Access should response faster to your request as compared to another request because the record based on the primary key.
- Foreign key: Foreign key provides a link between two tables but must one of the table record is primary key and the combination of the both which is unique make a foreign key.in other words we can day foreign key is a record in one table that is primary key in another table Majority of tables in database follow the concept of foreign key only. It can also accept multiple null values and a table can also have more than one foreign key.
There are many more keys in database like super key, candidate key, composite key, secondary or alternative key to know more about the keys in database get help in Database management help or you can also take help from our online tutors by Live chat
Database Relationships
As we know databases are divided into many tables and most of them are related to each other like an organization have a database table of each employee department wise and how an employee of one department connect to another department employee recoded in another table which shows the relationship table. So now the purpose of separating data into tables is to establish such table which reduce data redundancy. So there are three types of relationships in database.
- One-to-One: which determine a record in one table related to only one record in another table. Example of one-to-one relations are one employee belongs to one organization, one pair of jeans has one brand name, a software program is made by one organization.
- One-to-Many: One record of one table relates to many records of another table. One of the typical example of one-to-many relation is a one user has many addresses. Some of the basic examples are one employer has many employees, one car has many seats or one guitar has many strings.
- Many-to-Many: One record in a table can be related to one or more records in another table, and one or more records in the second table can be related to one or more records in the first table. Typical example of many-to-many relationship are let suppose a database contains two tables, one of students and one of subjects. So a student can take many subjects while a subject can be studied by many students at the same time.
