How to remove duplicate in sql

Query delete duplicates

DELETE FROM dups a USING (
      SELECT MIN(ctid) as ctid, key
        FROM dups 
        GROUP BY key HAVING COUNT(*) > 1
      ) b
      WHERE a.key = b.key 
      AND a.ctid <> b.ctid

Sql delete duplicate

-- Oracle
DELETE films
WHERE rowid NOT IN (
    SELECT min(rowid)
    FROM films
    GROUP BY title, uk_release_date
);

How to remove duplicate in sql

Distinct: helps to remove all the duplicate
records when retrieving the records from a table.

SELECT DISTINCT FIRST_NAME FROM VISITORS;

Sql delete duplicate rows but keep one

# Step 1: Copy distinct values to temporary table
CREATE TEMPORARY TABLE tmp_user (
    SELECT id, name 
    FROM user
    GROUP BY name
);

# Step 2: Remove all rows from original table
DELETE FROM user;

# Step 3: Remove all rows from original table
INSERT INTO user (SELECT * FROM tmp_user);

# Step 4: Remove temporary table
DROP TABLE tmp_user;

Source: designcise.com

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