mysql sum(if())和count(if())的用法说明

SELECT SUM(if(cateGory=1,size,0)) ,COUNT(if(category=1,true,null)) FORM t_file;

sum（if(category=1,size,0))

count(if(category=1,true,null))

SELECT
	p.Id Id,
	p.ImgUrl ImgUrl,
	p.Title Title,
	p.ReferOutPrice ReferOutPrice,
	e.`Status`,
	SUM(IF(e.`Status`=1 OR e.`Status`=2, ed.Number,0))
FROM
	Product p
	LEFT JOIN EBOrdersDetails ed ON p.id = ed.ProductId
	LEFT JOIN EBOrders e ON ed.PurchaseNo = e.PurchaseNo 
WHERE
	p.StoreId = 143 
	AND p.`Status` >-1
  GROUP BY p.Id