MySQL, как сделать COUNT (*) на запрос с объединениями?

Question

Кто-нибудь знает, как я могу выполнить COUNT (*) для такого запроса?

SELECT reviews.review_id, reviews.reviewers_rating, reviews.reviewers_name, reviews.review_date, reviews.pros, reviews.cons, products.product_name, products.slug, products.community_rating, products.number_of_votes, products.users_rating, products.thumb_link, categories.category_name_single
FROM reviews
LEFT JOIN products ON reviews.product_id = products.product_id
LEFT JOIN categories ON products.category = categories.category_id
WHERE reviews.approved =1
ORDER BY reviews.review_date DESC

Спасибо! * * 1004

Answer 1

Попробуйте это:

SELECT Count(reviews.review_id), reviews.review_id, reviews.reviewers_rating, reviews.reviewers_name,  reviews.review_date, reviews.pros, reviews.cons, products.product_name, products.slug, products.community_rating, products.number_of_votes, products.users_rating, products.thumb_link, categories.category_name_single
FROM reviews
LEFT JOIN products ON reviews.product_id = products.product_id
LEFT JOIN categories ON products.category = categories.category_id
WHERE reviews.approved =1
Group By reviews.review_id
ORDER BY reviews.review_date DESC

Answer 2

Left Join не нужны, так же, как и порядок, и вам не нужно считать все поля, одного будет достаточно

SELECT COUNT(review_id) FROM reviews WHERE approved =1

EDIT:
, если вы хотите считать отзывы о продуктахчем вы должны сделать что-то вроде этого:

SELECT products.*, count(r.review_id) AS reviews_count FROM products AS p
LEFT JOIN reviews AS r ON p.product_id = r.product_id AND r.approved=1
GROUP BY products.product_id

Answer 3

SELECT COUNT(*) FROM reviews
LEFT JOIN products ON reviews.product_id = products.product_id
LEFT JOIN categories ON products.category = categories.category_id
WHERE reviews.approved = 1 AND ...
ORDER BY reviews.review_date DESC