Arreglar entradas duplicadas de DB (error de MySQL)

Para enumerar todas las anomalías:

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

Hay algunas formas de eliminar los duplicados y su camino dependerá en gran medida de la cantidad de duplicados que tenga.

Consulte esto SO pregunta sobre formas de eliminarlos de su mesa.

Aquí está la solución que proporcioné allí:

-- 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;