Использование общего предложения WHERE при использовании UNIONS в SQL

Question

Я пытаюсь вернуть результаты MATCH() AGAINST() для нескольких таблиц, используя UNIONS, единственная проблема - некоторые строки возвращают релевантность 0, я хочу исключить их. После профсоюзов есть способ использовать "ГДЕ актуальность> 0"

Ниже немного моего SQL

SELECT pages.content AS search, page_info.url AS link, MATCH(pages.content) AGAINST('Wales') as relevance 
FROM page_content
LEFT JOIN pages ON (page_info.page = pages.id)

UNION

SELECT products_real.name AS search, products_real.event AS link, MATCH(products_real.name, products_real.description) AGAINST ('Wales') as relevance
FROM product_real

ORDER BY relevance DESC

Так что в любом случае я могу добавить ГДЕ релевантность> 0, прежде чем ORDER BY

большое спасибо

Answer 1

Попробуйте использовать производную таблицу

SELECT * 
FROM
  (SELECT 
    pages.content AS search, 
    page_info.url AS link, 
    MATCH(pages.content) AGAINST('Wales') as relevance  
  FROM page_content 
  LEFT JOIN pages ON (page_info.page = pages.id) 
  UNION 
  SELECT 
    products_real.name AS search, 
    products_real.event AS link, 
    MATCH(products_real.name, products_real.description) AGAINST ('Wales') as relevance 
  FROM product_real) myQuery
Where myQuery.relevance <> 0
ORDER BY myQuery.relevance DESC

Answer 2

Вы можете добавить его к каждому запросу или в конце:

SELECT pages.content AS search, page_info.url AS link, MATCH(pages.content) AGAINST('Wales') as relevance 
FROM page_content
LEFT JOIN pages ON (page_info.page = pages.id)
WHERE relevance > 0

UNION

SELECT products_real.name AS search, products_real.event AS link, MATCH(products_real.name, products_real.description) AGAINST ('Wales') as relevance
FROM product_real
WHERE relevance > 0

ORDER BY relevance DESC



SELECT search, relevance FROM
(

SELECT pages.content AS search, page_info.url AS link, MATCH(pages.content) AGAINST('Wales') as relevance 
FROM page_content
LEFT JOIN pages ON (page_info.page = pages.id)

UNION

SELECT products_real.name AS search, products_real.event AS link, MATCH(products_real.name, products_real.description) AGAINST ('Wales') as relevance
FROM product_real
) D
WHERE relevance > 0
ORDER BY relevance DESC