My left join union right join isn't quite working - I'm trying to simulate a full outer join

Question

I am trying to do a full outer join of several tables in Drupal 8. MySQL doesn't support full outer join so I'm using a left join union right join.

It gets most of the data but in the materials that I am querying for, I know there are multiple materials but I am only getting one. I can't see what I am doing wrong.

I am directly accessing the db and not using helper functions because this is actually for a mobile app I am writing, that queries the database from phones or tablets:

    $query_phrase = "select 
                     commerce_product_field_data.title as title,
                     commerce_product_field_data.product_id as product_id,
                     commerce_product__8fd244ef14.field_has_multiple_configuration_value as has_multiple_configuration,
                     commerce_product__field_barcode.field_barcode_value as barcode,
                     commerce_product__field_price.field_price_number as price,
                     commerce_product__field_price.field_price_currency_code as currency_code,
                     commerce_product__field_sku.field_sku_value as sku,
                     node_field_data.title as material_name,
                     file_managed.uri as uri,
                     file_managed.filename as filename
                     
                     from {commerce_product_field_data}
                     
                     left join commerce_product__8fd244ef14 on product_id = commerce_product__8fd244ef14.entity_id
                     left join commerce_product__field_barcode on product_id = commerce_product__field_barcode.entity_id
                     left join commerce_product__field_price on product_id = commerce_product__field_price.entity_id
                     left join commerce_product__field_sku on product_id = commerce_product__field_sku.entity_id
/*not working*/      left join commerce_product__field_materials  on product_id = commerce_product__field_materials.entity_id
/*not working*/      left join node_field_data on commerce_product__field_materials.field_materials_target_id = node_field_data.nid
                     left join file_managed on product_id = file_managed.fid";

       $query_phrase .= " union ";
                     
    $query_phrase .= "select 
                     commerce_product_field_data.title as title,
                     commerce_product_field_data.product_id as product_id,
                     commerce_product__8fd244ef14.field_has_multiple_configuration_value as has_multiple_configuration,
                     commerce_product__field_barcode.field_barcode_value as barcode,
                     commerce_product__field_price.field_price_number as price,
                     commerce_product__field_price.field_price_currency_code as currency_code,
                     commerce_product__field_sku.field_sku_value as sku,
                     node_field_data.title as material_name,
                     file_managed.uri as uri,
                     file_managed.filename as filename
                     
                     from {commerce_product_field_data}
                     
                     right join commerce_product__8fd244ef14 on product_id = commerce_product__8fd244ef14.entity_id
                     right join commerce_product__field_barcode on product_id = commerce_product__field_barcode.entity_id
                     right join commerce_product__field_price on product_id = commerce_product__field_price.entity_id
                     right join commerce_product__field_sku on product_id = commerce_product__field_sku.entity_id
/*not working*/      right join commerce_product__field_materials  on product_id = commerce_product__field_materials.entity_id
/*not working*/      right join node_field_data on commerce_product__field_materials.field_materials_target_id = node_field_data.nid
                     right join file_managed on product_id = file_managed.fid";
                     
       $query_phrase .=  " where commerce_product__field_barcode.field_barcode_value = :barcode";
                     
                     
    $query = db_query($query_phrase, array(":barcode" => "334242"));

When I debug my results I get:

Array
(
    [title] => Dummy Product
    [product_id] => 2
    [has_multiple_configuration] => 0
    [barcode] => 334242
    [price] => 325.000000
    [currency_code] => USD
    [sku] => dummy sku
    [material_name] => test material
    [uri] => public:a

But I know I have more than one material.

Answer 1

You're missing the where clause in the left join part of the query.

$query_phrase = "select 
     commerce_product_field_data.title as title,
     commerce_product_field_data.product_id as product_id,
     commerce_product__8fd244ef14.field_has_multiple_configuration_value as has_multiple_configuration,
     commerce_product__field_barcode.field_barcode_value as barcode,
     commerce_product__field_price.field_price_number as price,
     commerce_product__field_price.field_price_currency_code as currency_code,
     commerce_product__field_sku.field_sku_value as sku,
     node_field_data.title as material_name,
     file_managed.uri as uri,
     file_managed.filename as filename

     from {commerce_product_field_data}

     left join commerce_product__8fd244ef14 on product_id = commerce_product__8fd244ef14.entity_id
     left join commerce_product__field_barcode on product_id = commerce_product__field_barcode.entity_id
     left join commerce_product__field_price on product_id = commerce_product__field_price.entity_id
     left join commerce_product__field_sku on product_id = commerce_product__field_sku.entity_id
     left join commerce_product__field_materials  on product_id = commerce_product__field_materials.entity_id
     left join node_field_data on commerce_product__field_materials.field_materials_target_id = node_field_data.nid
     left join file_managed on product_id = file_managed.fid";

   $query_phrase .=  " where commerce_product__field_barcode.field_barcode_value = :barcode";

   $query_phrase .= " union ";

$query_phrase .= "select 
     commerce_product_field_data.title as title,
     commerce_product_field_data.product_id as product_id,
     commerce_product__8fd244ef14.field_has_multiple_configuration_value as has_multiple_configuration,
     commerce_product__field_barcode.field_barcode_value as barcode,
     commerce_product__field_price.field_price_number as price,
     commerce_product__field_price.field_price_currency_code as currency_code,
     commerce_product__field_sku.field_sku_value as sku,
     node_field_data.title as material_name,
     file_managed.uri as uri,
     file_managed.filename as filename

     from {commerce_product_field_data}

     right join commerce_product__8fd244ef14 on product_id = commerce_product__8fd244ef14.entity_id
     right join commerce_product__field_barcode on product_id = commerce_product__field_barcode.entity_id
     right join commerce_product__field_price on product_id = commerce_product__field_price.entity_id
     right join commerce_product__field_sku on product_id = commerce_product__field_sku.entity_id
     right join commerce_product__field_materials  on product_id = commerce_product__field_materials.entity_id
     right join node_field_data on commerce_product__field_materials.field_materials_target_id = node_field_data.nid
     right join file_managed on product_id = file_managed.fid";

   $query_phrase .=  " where commerce_product__field_barcode.field_barcode_value = :barcode";