Interview Query

ATM Robbery

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There was a robbery from the ATM at the bank where you work. Some unauthorized withdrawals were made, and you need to help your bank find out more about those withdrawals.

However, the only information you have is that there was more than 1 withdrawal, they were all performed in 10-second gaps, and no legitimate transactions were performed in between two fraudulent withdrawals.

We’re given a table of bank transactions with three columns, user_id, a deposit or withdrawal value transaction_value, and created_at time for each transaction.

Write a query to retrieve all user IDs in ascending order whose transactions have exactly a 10-second gap from one another.

Note: Assume that there are only withdrawals from the ATM, which are denoted with a positive transaction_value



bank_transactions table

Column Type
user_id INTEGER
created_at DATETIME
transaction_value FLOAT

For given table bank_transactions:

user_id created_at transaction_value
1 2017-01-01 10:10:15 10
2 2017-01-01 11:11:11 20
3 2017-01-01 12:12:12 10
4 2017-01-01 10:10:20 30
5 2017-01-01 10:10:34 40
6 2017-01-01 11:11:21 50


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MySQL 8.0.17
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