Question

我这里有问题;当我查询时：

SELECT product.*,product_description.*,COUNT(product_image.*) 
FROM " . DB_PREFIX . "product  
INNER JOIN product_description ON product.product_id = product_description.product_id 
INNER JOIN product_image ON product.product_id = product_image.product_id 
ORDER BY product.date_modified DESC

我想为table product_image选择3个表n 1个计数，但是我收到了这个错误：

注意：错误：您的SQL语法中有错误;检查手册对应于您的MySQL服务器版本，以获得正确的语法在'）附近使用FROM产品INNER JOIN product_description ON product.product_id = product_'在第1行错误号：1064 SELECT 产品。，product_description。，COUNT（product_image。）FROM产品 INNER JOIN product_description ON product.product_id = product_description.product_id INNER JOIN product_image ON product.product_id = product_image.product_id ORDER BY product.date_modified DESC

Answer 1

您不应该使用COUNT这样的功能。加入表时COUNT(TableName.*)。您需要使用其中任何一列，例如COUNT(TableName.ColumnName)。

例如COUNT(product_image.ID)

See this SQLFiddle

Answer 2

使用派生查询计算

SELECT 
    product.*,
    product_description.*,
    pi.Count as T_Count
FROM " . DB_PREFIX . "product  
INNER JOIN product_description ON product.product_id = product_description.product_id 
INNER JOIN (SELECT product_id , count(*) as Count FROM product_image) as pi ON product.product_id = pi.product_id 
ORDER BY product.date_modified DESC

Answer 3

试试这个::

SELECT 
product.*,
product_description.*,
COUNT(1) 
FROM " . DB_PREFIX . "product  
INNER JOIN product_description ON product.product_id = product_description.product_id 
INNER JOIN product_image ON product.product_id = product_image.product_id 
ORDER BY product.date_modified DESC

MySQL中有三个表连接计数

3 个答案:

See this SQLFiddle