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Intro to Databases

What is a database?​

According to Oracle, a database is an "organized collection of structured information, or data, typically stored electronically in a computer system." In simplistic terms, it's a file or document of tangible or intangible data about a particular item. For example, information collected to describe a person would be that individual's name, age, dob, weight, height, etc. A collection of individuals or items would assemble a table, and a group of tables would form a database.

What's a table?

A table represents a subject or event in an application

Types of databases​

Relational​

This type of database defines database relationships in the form of tables. It is also called Relational DBMS, which is the most popular DBMS type in the market. Database example of the RDBMS system include MySQL, Oracle, and Microsoft SQL Server database.

🥇 Popular Relational DBMS:​

NoSQL​

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🥇 Popular NoSQL DBMS:​

  • MongoDB
  • DynamoDB
  • ORACLE
  • SQL SERVER

What is Structured Query Language (SQL)?​

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The database design process​

The design process consists of the following steps:​

1. Determine the purpose of your database
This helps prepare you for the remaining steps.
2. Find and organize the information required
Gather all of the types of information you might want to record in the database, such as product name and order number.
3. Divide the information into tables
Divide your information items into major entities or subjects, such as Products or Orders. Each subject then becomes a table.
4. Turn information items into columns
Divide your information items into major entities or subjects, such as Products or Orders. Each subject then becomes a table.
Decide what information you want to store in each table. Each item becomes a field, and is displayed as a column in the table. For example, an Employees table might include fields such as Last Name and Hire Date.
5. Specify primary keys
Divide your information items into major entities or subjects, such as Products or Orders. Each subject then becomes a table.
Decide what information you want to store in each table. Each item becomes a field, and is displayed as a column in the table. For example, an Employees table might include fields such as Last Name and Hire Date.
6. Specify primary keys
Divide your information items into major entities or subjects, such as Products or Orders. Each subject then becomes a table.
Decide what information you want to store in each table. Each item becomes a field, and is displayed as a column in the table. For example, an Employees table might include fields such as Last Name and Hire Date.
Choose each table’s primary key. The primary key is a column that is used to uniquely identify each row. An example might be Product ID or Order ID.
7. Set up the table relationships
Look at each table and decide how the data in one table is related to the data in other tables. Add fields to tables or create new tables to clarify the relationships, as necessary.
8. Refine your design
Analyze your design for errors. Create the tables and add a few records of sample data. See if you can get the results you want from your tables. Make adjustments to the design, as needed.
9. Apply the normalization rules
Apply the data normalization rules to see if your tables are structured correctly. Make adjustments to the tables, as needed.

Primary Key​

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Secondary Key​

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Constraints​

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