Onsurity Technologies Data Analyst Interview Questions and Answers

Raw data can be cleaned by removing duplicates, handling missing values, standardizing formats, and correcting errors.

• Remove duplicates by identifying unique identifiers and filtering out redundant entries.

• Handle missing values by imputing with mean, median, or mode values or removing rows with missing data.

• Standardize formats by converting data into a consistent format (e.g. date formats, units of measurement).

• Correct...read more

To establish a relationship between two tables, use a common key or field that links the records in both tables.

• Use primary and foreign keys to establish relationships between tables.

• Primary key in one table should match the foreign key in another table.

• Types of relationships include one-to-one, one-to-many, and many-to-many.

• Examples: CustomerID in a Customers table can be linked to CustomerID in Orders table.