need help building a query to detect duplicates on multiple columns

Question

I have the following table

create table catalog_product_entity_varchar
(
    value_id     int auto_increment comment 'Value ID'
        primary key,
    attribute_id smallint unsigned default 0 not null comment 'Attribute ID',
    store_id     smallint unsigned default 0 not null comment 'Store ID',
    entity_id    int unsigned      default 0 not null comment 'Entity ID',
    value        varchar(255)                null comment 'Value',  
)

I want to find all entity_ids where attribute_id = 86 for the same store_id where the value is the same.

For example for the columns attribute_id, store_id, entity_id, value

86, 1, 1, mypath

is duplicate with

86, 1, 2, mypath

but is not duplicate with

86, 2, 1, mypath

The result would be entity_id, store_id, value

Any help is appreciated.

Answer 1

You can accomplish this with grouping on your store_id and value in a CTE or subquery to get the dupes and then re-joining the dupes to your catalog_product_entity_varchar table like so:

WITH CTE_Dupes AS
(
     SELECT store_id, value
     FROM catalog_product_entity_varchar
     WHERE attribute_id = 86
     GROUP BY store_id, value
     HAVING COUNT(1) > 1
)

SELECT C.entity_id, C.store_id, C.value
FROM catalog_product_entity_varchar C
INNER JOIN CTE_Dupes D
    ON C.store_id = D.store_id
    AND C.value = D.value
WHERE C.attribute_id = 86