Correction des entrées en double de la base de données (bogue MySQL)

Pour lister toutes les anomalies :

SELECT name, count(*) FROM TableA GROUP BY name HAVING count(*) > 1;

Il existe plusieurs façons de supprimer les doublons et votre chemin dépendra fortement du nombre de doublons que vous avez.

Voir ceci SO question pour savoir comment les supprimer de votre table.

Voici la solution que j'y ai fournie :

-- Setup for example
create table people (fname varchar(10), lname varchar(10));

insert into people values ('Bob', 'Newhart');
insert into people values ('Bob', 'Newhart');
insert into people values ('Bill', 'Cosby');
insert into people values ('Jim', 'Gaffigan');
insert into people values ('Jim', 'Gaffigan');
insert into people values ('Adam', 'Sandler');

-- Show table with duplicates
select * from people;

-- Create table with one version of each duplicate record
create table dups as 
    select distinct fname, lname, count(*) 
    from people group by fname, lname 
    having count(*) > 1;

-- Delete all matching duplicate records
delete people from people inner join dups 
on people.fname = dups.fname AND 
   people.lname = dups.lname;

-- Insert single record of each dup back into table
insert into people select fname, lname from dups;

-- Show Fixed table
select * from people;