Databases

• Definition: SQL is a standardised language used to manage and manipulate relational databases.
• Common Commands:
  • SELECT: Retrieves data from a database.
  • INSERT: Adds new data to a table.
  • UPDATE: Modifies existing data.
  • DELETE: Removes data from a table.
  • CREATE: Defines a new table or database.
  • ALTER: Modifies an existing table structure.
  • DROP: Deletes a table or database.

Example:

• SELECT Statement: SELECT * FROM Students WHERE Grade = 'A'; retrieves all students with an 'A' grade.

• Definition: Relational databases organise data into tables (rows and columns) and use relationships to link related data.
• Key Concepts:
  • Tables: Structures that store data in rows and columns.
  • Primary Key: A unique identifier for each record in a table.
  • Foreign Key: A field that creates a relationship between two tables.
  • Indexes: Structures that improve the speed of data retrieval.

Example:

• Table Structure:
  • Students Table: Contains columns like StudentID, Name, Grade.
  • Courses Table: Contains columns like CourseID, CourseName.
  • Relationship: StudentID in Courses table can reference StudentID in Students table.

• Definition: Data management involves the practices, processes and tools used to manage and protect data throughout its lifecycle.
• Key Activities:
  • Data Storage: Efficiently storing data in databases.
  • Data Retrieval: Extracting relevant data using queries.
  • Data Security: Protecting data from unauthorised access and breaches.
  • Data Backup: Creating copies of data to prevent loss.
  • Data Integrity: Ensuring accuracy and consistency of data.

Example:

• Data Backup: Regularly creating copies of the database to protect against data loss.