SQL Proficiency

What does the COALESCE function do in SQL?

• Returns the first non-null value in a list.

• Combines multiple columns into one.

• Converts null values to zeros.

• Checks if a value exists in a subquery.

Which of the following is not a valid SQL aggregate function?

• • SUM()

• • MAX()

• • MIN()

• ADD()

Which SQL statement is used to return only different values?

• • SELECT DISTINCT

• SELECT UNIQUE

• SELECT DIFFERENT

• SELECT VARIETY

Which of the following SQL clauses is used to filter groups of rows after the aggregation is performed?

• WHERE

• HAVING

• GROUP BY

• FILTER

Error: line 1:8: Column 'user_id' cannot be resolved

What does this SQL error message mean and how can it be resolved?

• The SQL statement is trying to use user_id in a subquery where it is not available.

• The column user_id does not exist in the table being queried.

• The user_id column is being referenced without specifying the table alias in a join.

• There is a syntax error in the SQL query, possibly due to a missing comma or incorrect keyword.

How can you limit the number of rows returned in a Query?

(a)  

Which of the following SQL statements correctly uses a Common Table Expression (CTE) to find the total transaction volume for each user and then uses a SUBQUERY to list user_ids whose total transactions exceed 100,000?

• hj

•  uyy

Answer explanation

The answer on the left doesn't use a Subquery.

Also, don't try to run this in Revolut, we have trillions of transactions and you will reach the time limit of 30 minutes 0-0

Which Functions will allow you to make text Lower, Upper.

• Lower() and Upper()

• Low() and Up()

• Text()

• Substring()

How to Get the Difference Between Two Dates in Trino SQL?

• DATE_DIFF()

• DATE_DIFFERENCE()

• DATEDIF()

• DIFF_DATE()

Answer explanation

In Revolut we use Trino SQL, the functions vary slightly from SQL type, it's normal for a DA to read documentation about a Specific Database while creating a Query.

For Trino check here: https://trino.io