remove duplicate data from sql table code example
Example 1: sql server delete records that have a single duplicate column
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;
Example 2: sql delete duplicate rows but keep one
CREATE TEMPORARY TABLE tmp_user (
SELECT id, name
FROM user
GROUP BY name
);
DELETE FROM user;
INSERT INTO user (SELECT * FROM tmp_user);
DROP TABLE tmp_user;