Databases and SQL

Define a primary key and its role in a database.

• A primary key is a specific data type in PostGreSQL.

• A primary key can contain duplicate values across records.

• A primary key is an optional field that can be left blank.

• A primary key is a unique identifier for records in a database, ensuring each record is distinct.

What is a foreign key and how does it establish relationships?

• A foreign key establishes relationships by linking a field in one table to the primary key of another table, ensuring data integrity.

• A foreign key is used to delete records from a table.

• A foreign key is a unique identifier for a table that ensures that all rows are distinct.

• A foreign key is a type of index that speeds up queries.

What is the purpose of database normalization?

• To simplify complex queries by merging tables.

• To minimize redundancy and dependency by organizing fields and table relationships.

• To enhance security by restricting data access and creating group and user roles.

• To increase data duplication for faster access.

Which of the following are different types of SQL joins?

• INNER JOIN

• SELF JOIN

• FULL JOIN

• LEFT JOIN

What wildcard character do you use to designate "all" in a SQL query?

• +

• ^

• *

• ~

What is the significance of data integrity constraints in a database?

• Data integrity constraints are optional for database performance.

• Data integrity constraints are crucial for maintaining accurate, consistent, and reliable data in a database.

• Data integrity constraints are used to increase data redundancy within each table.

• Data integrity constraints only affect the speed of data retrieval and query optimization.

Rows in a database are known as _______.

Which of the following are types of constraints in RDBMS?

• Attribute Constraints

• Key Constraints

• Referential Integrity Constraints

• A, B, and C

Explain the concept of first normal form (1NF).

• A table is in First Normal Form (1NF) if it contains nested tables and arrays.

• A table is in First Normal Form (1NF) if it allows duplicate rows and columns.

• A table is in First Normal Form (1NF) if it has no restrictions on data types in columns.

• A table is in First Normal Form (1NF) if it contains only atomic values, each column has a unique name, and each row is unique.

What is referential integrity and why is it important?

• Referential integrity is a method for encrypting sensitive data.

• Referential integrity is only relevant for non-relational databases.

• Referential integrity ensures faster query performance in databases.

• Referential integrity is crucial for maintaining data consistency and preventing errors in relational databases.