在左联接表mysql中选择COUNT(） - SELECT COUNT() in a left join table mysql

SELECT COUNT() in a left join table mysql

本文关键字：选择 COUNT mysql | 更新日期: 2023-09-27

我正在尝试统计任何给定月份的新潜在客户数量和已关闭的潜在客户数量。下面的查询正确返回月份数组，但如果月份中有任何潜在客户或成交，则只计算1，而不是当月发生的实际数字。你知道我做错了什么吗？

查询：

$productSql = "SELECT months.monthnum as monthnum, COUNT(contacts.lead_date) as lead_date_month, COUNT(contacts.close_date) as close_date_month, contacts.rep as rep 
                FROM months 
                LEFT JOIN contacts 
                ON months.monthnum = MONTH(contacts.lead_date) 
                    AND months.monthnum = MONTH(contacts.close_date) 
                    AND contacts.compid='$compid' 
                    AND YEAR(contacts.lead_date) = '$year' 
                    AND YEAR(contacts.close_date) = '$year' 
                    AND contacts.rep = '$rep' 
                GROUP BY months.monthnum 
                ORDER BY months.monthnum ASC";
$productResult = mysql_query($productSql, $link) or die(mysql_error());

$label[] = $productRow['monthnum'];
$lead[] = $productRow['lead_date_month'];
$close[] = $productRow['close_date_month'];
};
echo "[".json_encode($label).",".json_encode($lead).",".json_encode($close)."]";

结果：

[["January","February","March","April","May","June","July","August","September","October","November","December"],
["0","0","0","0","0","0","0","0","1","1","0","0"],
["0","0","0","0","0","0","0","0","1","1","0","0"]]

**请不要因为我使用mysql而责备我。这个项目一完成，我就把它扔掉。

构建JOIN条件的方式只能从MONTH(contacts.lead_date)=MONTH(contacts.close_date)的记录中获得结果。

为了解决这个问题并获得实际计数，我建议将语句拆分为两个查询：

SELECT 
    a.monthnum, 
    a.lead_date_month, b.close_date_month, 
    b.close_date_month / a.lead_date_month
FROM
(
-- Count number of new leads
SELECT 
    months.monthnum as monthnum, 
    COUNT(*) as lead_date_month, 
    contacts.rep as rep 
FROM 
    months 
    LEFT JOIN contacts
ON 
    months.monthnum = MONTH(contacts.lead_date) 
    AND contacts.compid='$compid' 
    AND YEAR(contacts.lead_date) = '$year' 
    AND contacts.rep = '$rep' 
GROUP BY 
    months.monthnum 
ORDER BY 
    months.monthnum ASC
) as a
JOIN
(
-- Count number of closed leads
    SELECT 
    months.monthnum as monthnum, 
    COUNT(*) as close_date_month, 
    contacts.rep as rep 
FROM 
    months 
    LEFT JOIN contacts
ON 
    months.monthnum = MONTH(contacts.close_date) 
    AND contacts.compid='$compid' 
    AND YEAR(contacts.close_date) = '$year' 
    AND contacts.rep = '$rep' 
GROUP BY 
    months.monthnum 
ORDER BY 
    months.monthnum ASC
) as b
ON a.monthnum = b.monthnum

MySQL也没那么糟糕。但是MariaDB更好，你是对的：-）