php - MySQL: Limiting LEFT OUTER JOIN / Left outer join where id = #

one text

Solution:

Add the related clause with AND operator in ON clause

    SELECT `custom_fields`.*, `custom_field_filter`.`fieldid` as `selected` 
    FROM `custom_fields` 
    LEFT OUTER JOIN `custom_field_filter` 
    ON `custom_fields`.`ID` = `custom_field_filter`.`fieldid` 

        AND `custom_field_filter`.`formid` = 6

    ORDER BY `custom_fields`.`ID` ASC

the where clause on the left joined table work as an inner join .. instead the use of a condition on the ON clause preserve the left join