Database Management Concepts Flashcards

Which SQL statement is used to modify existing records in a table?

Answer: UPDATE

The UPDATE statement changes existing data in one or more rows of a table based on a specified condition.

What is data integrity in a database?

Answer: The accuracy, consistency, and reliability of data stored in a database

Data integrity ensures that data remains accurate, consistent, and trustworthy throughout its lifecycle in the database.

Which type of database backup copies only the data that has changed since the last full backup?

Answer: Incremental backup

An incremental backup saves only the data that has changed since the last backup, reducing storage and time requirements.

What is a composite key in a relational database?

Answer: A primary key made up of two or more columns

A composite key uses two or more columns together to uniquely identify a row in a table.

Which SQL command is used to add a new column to an existing table?

Answer: ALTER TABLE ... ADD

ALTER TABLE with the ADD clause modifies an existing table's structure by adding a new column.

What is the difference between DELETE and DROP in SQL?

Answer: DELETE removes rows from a table; DROP removes the entire table

DELETE removes specific rows from a table while leaving the structure intact; DROP removes the entire table including its structure.

In the context of databases, what is sharding?

Answer: Splitting a large database horizontally across multiple servers

Sharding is a horizontal scaling technique that partitions data across multiple database instances to improve performance and capacity.