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Delete Duplicate MySQL rows but keep one


Delete Duplicate MySQL rows but keep one

By : Elijah Wood
Date : November 20 2020, 03:01 PM
With these it helps Consider this for your select. then just change the select * to delete A after confirming this gives the records you want to delete.
Think of it this way: you want a set of data with the max call duration Grouped by your 3 fields. Then, join this set on those 3 fields AND the max duration back to the base set to get all the unique calls joined to their max call duration. Any records not matching that max duration would have a null join; and thus those are the ones you want to delete.
code :
SELECT * 
FROM CALLS A
LEFT JOIN (SELECT call_from, call_to, Call_start_date, max(Call_Duration) mCD, min(ID) MID
            FROM calls
            GROUP BY call_from, call_to, Call_start_date) B
 on A.Call_from = B.call_from
and A.Call_to = B.call_to
and A.Call_start_date = B.call_Start_date
and A.call_duration = B.MCD
and A.ID = B.MID
WHERE B.mcd is null
DELETE A
FROM CALLS A
LEFT JOIN (SELECT call_from, call_to, Call_start_date, max(Call_Duration) mCD, min(ID) mid
            FROM CALLS Z
            GROUP BY call_from, call_to, Call_start_date) B
 on A.Call_from = B.call_from
and A.Call_to = B.call_to
and A.Call_start_date = B.call_Start_date
and A.call_duration = B.MCD
and A.ID = B.MID
WHERE B.mcd is null;


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Delete all Duplicate Rows except for One in MySQL?

Delete all Duplicate Rows except for One in MySQL?


By : Shreya Kshatriya
Date : March 29 2020, 07:55 AM
may help you .
Editor warning: This solution is computationally inefficient and may bring down your connection for a large table.
code :
DELETE n1 FROM names n1, names n2 WHERE n1.id > n2.id AND n1.name = n2.name
DELETE n1 FROM names n1, names n2 WHERE n1.id < n2.id AND n1.name = n2.name
INSERT INTO tempTableName(cellId,attributeId,entityRowId,value)
    SELECT DISTINCT cellId,attributeId,entityRowId,value
    FROM tableName;
Delete duplicate rows in mysql

Delete duplicate rows in mysql


By : meghana
Date : March 29 2020, 07:55 AM
I wish this help you I have a location mysql db contain 3 columns , Your query has numerous issues:
code :
DELETE FROM location
where country in (SELECT *
                  FROM table_name 
                  GROUP BY country, state, city 
                  having COUNT(*)>);
create temporary table tmpLocation as
    select country, state, city from location;

truncate table location;

insert into location(country, state, city)
    select distinct country, state, city
    from tmpLocation;

drop table tmpLocation;
MySQL - Add duplicate rows to archive table, then delete duplicate rows

MySQL - Add duplicate rows to archive table, then delete duplicate rows


By : incred
Date : March 29 2020, 07:55 AM
wish help you to fix your issue The solution to my problem is that when my first select was just '*', it was adding the two additional columns (MinId, count) to the result which made the column count different. By only grabbing the results of the 'enrollees' table and not the additional parameters of the subquery too, it corrects the column difference.
code :
INSERT INTO enrollees_duplicates (SELECT enrollees.* 
    FROM enrollees
    INNER JOIN (SELECT first_name, last_name, address1, city, state, zip, program_instance_id, MIN(id) AS MinId, COUNT(id) AS count FROM enrollees GROUP BY first_name, last_name, address1, city, state, zip, program_instance_id) b
    ON enrollees.first_name = b.first_name
        AND enrollees.last_name = b.last_name 
        AND enrollees.address1 = b.address1
        AND enrollees.city = b.city
        AND enrollees.state = b.state
        AND enrollees.zip = b.zip 
        AND count > 1 
        AND enrollees.program_instance_id = b.program_instance_id 
        AND enrollees.id != MinId);
How to delete duplicate rows from mysql

How to delete duplicate rows from mysql


By : Litos
Date : March 29 2020, 07:55 AM
With these it helps Your query fails because of a limitation in MySQL. Just rephrase it as a join. Here is one way:
code :
DELETE t
    FROM table t LEFT JOIN
    (SELECT MAX(column ) as column
     FROM table
     GROUP BY column
    ) tosave
    ON t.column = tosave.column
WHERE tosave.column is null; 
create temporary table temptable as
    select distinct column
    from tablename;

truncate table tablename;

insert into tablename(column)
    select column
    from temptable;
Delete ALL duplicate rows in MySQL table (Not except 1, all duplicate rows)

Delete ALL duplicate rows in MySQL table (Not except 1, all duplicate rows)


By : King Schultz
Date : March 29 2020, 07:55 AM
I think the issue was by ths following ,
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