Country Holidays Inn & Suites Interview Questions and Answers

Primary keys uniquely identify records in a table, while foreign keys establish relationships between tables.

• A primary key is a unique identifier for a record in a database table.

• Example: In a 'Customers' table, 'CustomerID' can be a primary key.

• A foreign key is a field in one table that links to the primary key of another table.

• Example: In an 'Orders' table, 'CustomerID' can be a foreign key referencing 'Customers'.

• Primary keys ensure data integrity, while foreign keys maint...read more

Drop command deletes the table structure along with data, while truncate command deletes only the data.

• Drop command removes the table structure and all its data, while truncate command only removes the data but keeps the table structure intact.

• Drop command is a DDL (Data Definition Language) command, while truncate command is a DML (Data Manipulation Language) command.

• Drop command is slower than truncate command as it involves deleting the table structure.

• Example: DROP TABLE ...read more

Joins are SQL operations that combine rows from two or more tables based on related columns.

• INNER JOIN: Returns records with matching values in both tables. Example: SELECT * FROM A INNER JOIN B ON A.id = B.id;

• LEFT JOIN: Returns all records from the left table and matched records from the right table. Example: SELECT * FROM A LEFT JOIN B ON A.id = B.id;

• RIGHT JOIN: Returns all records from the right table and matched records from the left table. Example: SELECT * FROM A RIGHT ...read more

Star Schema is a type of database schema where a central fact table is connected to multiple dimension tables. Snowflake Schema is a normalized form of Star Schema where dimension tables are further normalized into sub-dimension tables.

• Star Schema has a central fact table connected to multiple dimension tables

• Snowflake Schema is a normalized form of Star Schema with sub-dimension tables

• Star Schema is denormalized for better query performance

• Snowflake Schema is normalized for ...read more

Delete removes specific records from a table; drop removes the entire table structure and its data.

• DELETE is a DML command used to remove specific rows from a table based on a condition.

• Example: DELETE FROM Employees WHERE EmployeeID = 1; removes the employee with ID 1.

• DROP is a DDL command that removes the entire table structure and all its data permanently.

• Example: DROP TABLE Employees; deletes the entire Employees table.

• DELETE can be rolled back if used within a transactio...read more

Fact tables contain quantitative data while dimension tables contain descriptive attributes.

• Fact tables store measurable, quantitative data such as sales revenue or quantity sold

• Dimension tables store descriptive attributes related to the data in the fact table, such as product name or customer details

• Fact tables are typically normalized while dimension tables are denormalized for easier querying

• Example: In a sales database, the fact table would contain sales data while dimen...read more