ZenQ Database Administrator DBA Interview Questions and Answers

Joins are used to combine data from two or more tables based on a related column.

• Joins are used in SQL to retrieve data from multiple tables.

• There are different types of joins such as inner join, left join, right join, and full outer join.

• Inner join returns only the matching rows from both tables.

• Left join returns all the rows from the left table and matching rows from the right table.

• Right join returns all the rows fr...read more

A foreign key is a column or a set of columns in a table that refers to the primary key of another table.

• It establishes a link between two tables.

• It ensures referential integrity.

• It helps in maintaining consistency in the database.

• It can be null or have duplicate values.

• Example: A 'customer' table may have a foreign key 'order_id' that refers to the primary key 'id' in the 'order' table.