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Detect Shared Payment Methods
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Detect Shared Payment Methods

MediumSQL · PostgreSQL

Problem

You are given Lyft-style account and payment data and need to identify users who share the same payment method with other accounts. Write a SQL query that returns each shared payment method along with the users linked to it, but only for active payment methods and non-deactivated accounts. The result should include the payment method token, the number of distinct linked users, and the user details for those flagged payment methods.

Schema

lyft_users
ColumnTypeDescription
user_idPKINTUnique user identifier
full_nameVARCHAR(100)User full name
emailVARCHAR(150)User email address
account_statusVARCHAR(20)Account status
payment_methods
ColumnTypeDescription
payment_method_idPKINTUnique payment method record
payment_tokenVARCHAR(64)Tokenized payment method identifier
method_typeVARCHAR(20)Payment method type
is_activeBOOLEANWhether the payment method is active
user_payment_methods
ColumnTypeDescription
link_idPKINTUnique link record
user_idINTLinked user
payment_method_idINTLinked payment method
linked_atDATEDate the link was created
Tableslyft_userspayment_methodsuser_payment_methods
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