Relational model facts for kids
The relational model is a way to organize information in a database. Think of a database as a super organized filing cabinet for digital information. This model was created by Edgar F. Codd in 1969.
In the relational model, all information is stored in tables. These tables are like spreadsheets. Each row in a table is called a "tuple" or a record. Each column is an "attribute" or a field. All these records together form a "relation," which is the table itself. A database built this way is called a relational database.
The main idea of the relational model is to make it easy to ask the database for information. You just tell the database what data you want. You don't need to know how the database stores or finds that data. The database system handles all the complex parts for you.
Most relational databases today use a special language called SQL. SQL helps you define what data goes into the database. It also helps you ask questions to get data out. These systems are a bit different from Codd's original idea. Codd strongly believed in sticking to his first principles.
Contents
How Data Is Organized
In a relational database, data is stored in tables. Each table has a name, like "Students" or "Courses." Each table also has columns, like "Student ID" or "Course Name."
Rows and Columns
Each row in a table represents one item or record. For example, in a "Students" table, each row would be one student. The columns hold different pieces of information about that item. For a student, columns might be "Name," "Age," and "Grade."
Linking Tables with Keys
Tables in a relational database can be linked together. This is done using special columns called "keys." A "primary key" is a unique ID for each row in a table. For example, a "Student ID" could be a primary key.
A "foreign key" is a column in one table that matches a primary key in another table. This link helps connect related information. For instance, a "Courses" table might have a "Teacher ID" column. This "Teacher ID" would be a foreign key that links to the "Teacher ID" primary key in a "Teachers" table. This way, you can easily find out which teacher teaches which course.
Asking Questions to the Database
The relational model makes it simple to get information. You use a language like SQL to ask questions. You tell the database what information you need. The database then finds and gives you that information.
What is SQL?
SQL stands for Structured Query Language. It's the most common language used with relational databases. With SQL, you can:
- Create new tables.
- Add new data to tables.
- Change existing data.
- Delete data.
- Most importantly, ask questions to retrieve specific data.
For example, you could ask: "Show me all students who are 14 years old." The database would then give you a list of those students.
Why the Relational Model is Important
The relational model changed how databases work. It made databases much easier to use and manage. Before this model, databases were often complex and hard to update.
Benefits of the Model
- Easy to understand: Tables are simple to visualize and work with.
- Flexible: You can easily add new data or change existing data.
- Powerful: You can ask complex questions and get specific answers.
- Data integrity: Keys help ensure that data is consistent and correct across tables.
The relational model is still the most popular way to organize databases today. Many websites, apps, and businesses rely on it every day.
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Relational model concepts.
See also
In Spanish: Modelo relacional para niños
