Database & Database Management System. ○ Relational Database. ○ Simple SQL Queries. ○ Database normalization. ○ RDBMS for an Inverted Text Index. Continuous, non-tiled, spatial database for adding spatial data to a relational database management system (RDBMS). • Database interface that couples spatial. or more related tables is called a relational database. There are other more formally declared in various database software is beyond the scope of this paper) .
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Examples and exercises in this book all use a language, Tutorial D, invented what a relational database is, what a database management system (DBMS) is. A database management system (DBMS) is a collection of Database management systems provide several functions in What is a relational database?. This tutorial explains the basics of DBMS such as its architecture, data data schemas, data independence, E-R model, relation model, relational database.
A major advantage of the non-relational database is that it can easily incorporate and store all kinds of Big Data, including unstructured and semi-structured data. This means you need to perform multiple queries and join data manually, which can pose challenges. What can online database software do? It often includes editing and collaboration functionality so that team members can discuss projects and share files.
Depending on the platform, the user may also be able to build forms that can be housed on a website and can deliver data directly to a database. Most online database software platforms also have advanced reporting capabilities. Quick Base is an online database platform with powerful, enterprise-grade features that's simple enough for anyone to build an app on and manage their data securely - without the skills of a pro developer.
What is a desktop database? Before complex data warehousing and before the cloud, there was the desktop database designed to run on a single machine. These solutions are simple and inexpensive, but also fairly limited in terms of data availability, storage, and functionality. What is a web-enabled database? The web-enabled database provides everything a standard database does, but all functionality can be utilized online, and all data can be accessed remotely and interactively.
Common components of a web-enabled database system are permanent online access, a web server and firewall, and application delivery via online database software and a website. The web-enabled database system is often coupled with a desktop platform. What is a server database?
Server databases are typically used to manage massive data stores, allowing multiple users to simultaneously access, modify, and update data and ensuring that data is reliable and consistent. While server databases are more expensive than other solutions, they are also more flexible, scalable, and powerful. What is the difference between on premise and hosted database software?
Many organizations license these programs at the same time, and organizations typically pay per user or via a subscription. However, hosted database software programs generally allow users to scale up more quickly.
The value of the primary key should not change. Primary key is used to reference other tables.
If you change its value, you have to change all its references; otherwise, the references will be lost. For example, phoneNumber may not be appropriate to be used as primary key for table Customers, because it might change.
Primary key often uses integer or number type. But it could also be other types, such as texts. However, it is best to use numeric column as primary key for efficiency. Primary key could take an arbitrary number. This arbitrary number is fact-less, as it contains no factual information.
Unlike factual information such as phone number, fact-less number is ideal for primary key, as it does not change. Primary key is usually a single column e. But it could also make up of several columns.
What is database software used for?
You should use as few columns as possible. Let's illustrate with an example: a table customers contains columns lastName, firstName, phoneNumber, address, city, state, zipCode. Name may not be unique. Phone number and address may change.
Hence, it is better to create a fact-less auto-increment number, say customerID, as the primary key. Step 3: Create Relationships among Tables A database consisting of independent and unrelated tables serves little purpose you may consider to use a spreadsheet instead.
The power of relational database lies in the relationship that can be defined between tables. The most crucial aspect in designing a relational database is to identify the relationships among tables. The types of relationship include: one-to-many one-to-one One-to-Many In a "class roster" database, a teacher may teach zero or more classes, while a class is taught by one and only one teacher. In a "company" database, a manager manages zero or more employees, while an employee is managed by one and only one manager.
In a "product sales" database, a customer may place many orders; while an order is placed by one particular customer. This kind of relationship is known as one-to-many. One-to-many relationship cannot be represented in a single table. For example, in a "class roster" database, we may begin with a table called Teachers, which stores information about teachers such as name, office, phone and email.
To store the classes taught by each teacher, we could create columns class1, class2, class3, but faces a problem immediately on how many columns to create. On the other hand, if we begin with a table called Classes, which stores information about a class courseCode, dayOfWeek, timeStart and timeEnd ; we could create additional columns to store information about the one teacher such as name, office, phone and email. However, since a teacher may teach many classes, its data would be duplicated in many rows in table Classes.
KEY POINTS OF THE CHAPTER
To support a one-to-many relationship, we need to design two tables: a table Classes to store information about the classes with classID as the primary key; and a table Teachers to store information about teachers with teacherID as the primary key.
We can then create the one-to-many relationship by storing the primary key of the table Teacher i. The column teacherID in the child table Classes is known as the foreign key. A foreign key of a child table is a primary key of a parent table, used to reference the parent table.
Take note that for every value in the parent table, there could be zero, one, or more rows in the child table. For every value in the child table, there is one and only one row in the parent table. Many-to-Many In a "product sales" database, a customer's order may contain one or more products; and a product can appear in many orders.
What is RDBMS
In a "bookstore" database, a book is written by one or more authors; while an author may write zero or more books. This kind of relationship is known as many-to-many.
Let's illustrate with a "product sales" database. We begin with two tables: Products and Orders.
The table products contains information about the products such as name, description and quantityInStock with productID as its primary key. The table orders contains customer's orders customerID, dateOrdered, dateRequired and status. Again, we cannot store the items ordered inside the Orders table, as we do not know how many columns to reserve for the items.
We also cannot store the order information in the Products table. To support many-to-many relationship, we need to create a third table known as a junction table , say OrderDetails or OrderLines , where each row represents an item of a particular order. For the OrderDetails table, the primary key consists of two columns: orderID and productID, that uniquely identify each row.
The many-to-many relationship is, in fact, implemented as two one-to-many relationships, with the introduction of the junction table. An order has many items in OrderDetails.
An OrderDetails item belongs to one particular order. A product may appears in many OrderDetails. Each OrderDetails item specified one product. One-to-One In a "product sales" database, a product may have optional supplementary information such as image, moreDescription and comment. Keeping them inside the Products table results in many empty spaces in those records without these optional data.
Furthermore, these large data may degrade the performance of the database. A record will only be created for those products with optional data. The two tables, Products and ProductDetails, exhibit a one-to-one relationship.
That is, for every row in the parent table, there is at most one row possibly zero in the child table.
The same column productID should be used as the primary key for both tables. Some databases limit the number of columns that can be created inside a table.Hierarchical database — In this, the information about the groups of parent or child relationships is present in the records which is similar to the structure of a tree.
A person has name. RDBMS supports the integrity constraints at the schema level. Majorly used in the applications that have query to larger database. It would obviously take away all the logs and active copies of the database. Net C CodeIgniter. View Updating Rule All the views of a database.