Understanding Databases: Concepts and Key Components

What is a Database?

A database is an organized collection of data, visualized as a container of information. The data is typically organized to model relevant aspects of reality. A Database Management System (DBMS) is a software package with computer programs that controls the creation, maintenance, and use of a database. It allows organizations to conveniently develop databases for various applications.

A database is an integrated collection of data records, files, and other objects. A DBMS allows different user application programs to concurrently access the same database. Typically, databases available on database servers are accessed through command-line or graphical user interface tools, referred to as front-ends; database servers are referred to as back-ends. This type of data access is referred to as a client-server model.

Relational Database Management Systems (RDBMS)

RDBMS is a DBMS based on the relational model introduced by E. F. Codd of IBM's San Jose Research Laboratory. Most popular databases currently in use are based on the relational model. The relational model for databases is based on first-order predicate logic, first formulated and proposed in 1969 by Edgar F. Codd. In the relational model, all data is represented in terms of tuples, grouped into relations. A database organized in terms of the relational model is a relational database.

The purpose of the relational model is to provide a declarative method for specifying data and queries: users directly state what information the database contains and what information they want from it, and let the DBMS software take care of describing data structures for storing the data and retrieval procedures for answering queries.

Key Database Concepts

• Item: What the database is storing information about.
• Field: Each question that we ask about our item.
• Record: A set of information stored in your database about one of the items.
• Value: The actual text, numerical amount, or date that you input while adding information to your database.
• Table: A collection of similar records arranged in a grid.
• Key Index (or Key Field): Each row is identified by the values appearing in a particular column.
• Column: A set of data values of a particular simple type, one for each row of the table. The columns provide the structure according to which the rows are composed.
• Row (Record or Tuple): Represents a single data item in a table.

In simple terms, a database table can be visualized as consisting of rows and columns or fields. Each row in a table represents a set of related data, and every row in the table has the same structure.

Primary and Foreign Keys

• Primary Key: A unique value that identifies a row in a table.
• Foreign Key: Identifies a column or set of columns in one table that refers to a column or set of columns in another table.

In a relation, the one side is always the parent and provides the primary key (PK) attributes to be copied. The many side of a relation is always the child, into which the foreign key (FK) attributes are copied.

Data Definition Language (DDL) and Data Manipulation Language (DML)

In a database, you can define the structure of the data and manipulate the data using commands.

Data Definition Language (DDL)

DDL is a standard for commands that define the different structures in a database. DDL statements create, modify, and remove database objects such as tables, indexes, and users. Common DDL statements are CREATE, ALTER, and DROP.

Data Manipulation Language (DML)

DML is a language that enables users to access and manipulate data in a database. The goal is to provide efficient human interaction with the system.

Additional Notes

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