WITH cte AS (
SELECT
contact_id,
first_name,
last_name,
email,
ROW_NUMBER() OVER (
PARTITION BY
first_name,
last_name,
email
ORDER BY
first_name,
last_name,
email
) row_num
FROM
sales.contacts
)
DELETE FROM cte
WHERE row_num > 1;
/*
Code language: SQL (Structured Query Language) (sql)
In this statement:
First, the CTE uses the ROW_NUMBER() function to find the duplicate rows
specified by values in the first_name, last_name, and email columns.
Then, the DELETE statement deletes all the duplicate rows but keeps only one
occurrence of each duplicate group.*/