Relational Database Structure and Terminology Conclusion
This module introduced you to the structure of a relational database and some of the terminology used to describe it.
You learned that the structure of a relational database is based on the relational model.
You also learned that the largest structure in a relational database is a table, which contains fields, records, and a primary key.
You discovered that using the primary-key field to link tables allows data to be accessed in a relational database.
Finally, you learned that Structured Query Language (SQL) is the programming language used to create relational databases, and that a relational database management system (RDBMS) is a software package used to manage relational databases.
Now that you have completed the lessons in this module, you should be able to:
- Describe the relational database model
- Describe the structure of a relational database
- Explain how relational database tables are linked to access data
- Explain why SQL is the lingua franca of relational databases
- Describe the functions of a relational database management system
Each database model provides a unique formal structure for its database type. As you might expect, there are advantages and disadvantages to each formal structure. The structure of a relational database was briefly discussed in this module.
It is beyond our scope to compare and contrast the relational model with the other three. Both the hierarchical and network models are used in many legacy database systems. However, you will rarely find new databases created from these two older models. The object-oriented model, on the other hand, is relatively new. It caught on in the mid-90s and continues to gain in popularity. In fact, some relational databases such as Oracle incorporate elements from the object-oriented model. Suffice to say that the advantages of the relational model outweigh its disadvantages; of the four 1)relational, 2)Object-oriented, 3)hierarchical, 4)network, it is the model of choice for most businesses.
This module introduced you to the following terms:
- data: The "raw facts" stored in a database.
- data definition language (DDL): A collection of programming statements that describe and define data and data relationships in a database.
- data integrity: A term used to describe the quality (in terms of accuracy, consistency, and validity) of data in a database,
in the sense that values required to enforce data relationships actually exist. Problems with data integrity occur when a value in one table that’s supposed to relate to a value in another can’t, because the second value either has been deleted or was never entered.
- data manipulation language (DML): A collection of programming statements used to manipulate a database.
- database model: A formal structure for organizing and linking data in a database.
- field: The smallest structure in a table; contains data describing the subject of a table.
- foreign key: A field (or combination of fields) used to link tables; a corresponding primary key field occurs in the same database.
- hierarchical model: A database model that organizes data in a top-down (inverted tree) structure.
- information: A collection of "raw facts" (data) organized in such a way that they have value
beyond the value of the facts themselves.
- network model: An extension of the hierarchical model. (See hierarchical model.)
- oject-oriented model: When database capabilities are combined with object programming language capabilities, the result is an object database management system (ODBMS).
- primary key: A field (or combination of fields) that uniquely identifies a record in a table.
- query: (v) To extract data from a database; (n.) a set of SQL statements for extracting particular data from a database.
- record: A particular instance of the subject of a table.
- relational database: A relational database is a database that conforms to the relational model, and refers to the data and schema of the database.
- Relational Database Management System (RDBMS): A software package that manages and provides access to a database.
These packages follow Codd’s 12 rules of relational databases and normally use SQL to access data.
- relational model: A formal structure that organizes data into relations (i.e., tables).
- table: A collection of data arranged in rows and columns. A table is the largest structure in a relational database.
- user views: Saved queries created with SQL. User views specify which users are permitted access to what data in a database.
In the next module, database design strategy and design tools will be discussed.
Relational Database Quiz
Before moving on to the next module, click the Quiz link below to check your knowledge of relational database structure and terminology.
Relational Database - Quiz
Ad Relational Database Design