How should I practice Duplicate Emails?

Start by reading the full statement, solve the visible examples, then compare the pattern against related World Wide Technology phone screen problems in FastPrep.

Is Duplicate Emails associated with World Wide Technology?

FastPrep tags this as a World Wide Technology phone screen coding practice problem when the problem catalog has that company and stage context.

Problem · Database

Duplicate Emails

● Easy

World Wide TechnologyINTERNPHONE SCREEN

Problem statement

You are given a table named contacts. Each row contains a unique contact_id and a non-null lowercase email.

Return every email that appears in more than one row. Include each duplicated email exactly once and sort the result by email in ascending order.

Table schema

MySQLPostgreSQL

Use the same input data with any supported language. Open the Schema tab in the editor to see the generated SQL setup or Pandas DataFrames.

contacts

Column	Type	Nullable	Description
contact_idPK	Integer	No	—
email	Text	No	—

Expected result

Your query or function must return these columns.

Column	Type	Nullable	Description
email	Text	No	—

Row order: must match exactly. Numeric tolerance: 0.

Constraints

contacts contains at most 10^5 rows.
contact_id is unique and non-null.
email is non-null lowercase text.
Email equality uses the exact stored value; do not trim or otherwise normalize it.