使用 Union 或 Join 在 where 语句中使用多个查询结果

Question

我需要合并 3 个求和查询的结果并在循环中回显结果。我被困在如何以正确的方式完成这项工作。我想使用 while 循环为每个客户端回显一行，显示按客户端名称分组的 3 个总和查询的结果：

客户名称 |到期总额 |现金销售应付总额 |赊销欠款总额

结果显示全部归功于客户。 noncashresult 显示全部归功于 Credit sales 的客户。 cashresult 显示所有应付现金销售的客户。

$result = mysql_query("SELECT `client_name` As `Client`, SUM(`due_to_client`) As `Total Due` 
FROM `Consignment` 
WHERE `payout_approved` = 'Yes' 
GROUP BY `client_name`"); 

$noncashresult = mysql_query("SELECT `client_name` As `Client`, SUM(`due_to_client`) As `Credit Total Due`
FROM `Consignment` 
WHERE `payout_approved` = 'Yes' AND `paymenttype` IN ('Credit') 
GROUP BY `client_name`");

$cashresult = mysql_query("SELECT `client_name` As `Client`, SUM(`due_to_client`) As `Cash Total Due`
FROM `Consignment` 
WHERE `payout_approved` = 'Yes' AND `paymenttype` IN ('Cash') 
GROUP BY `client_name`");

while($row = mysql_fetch_array($result))
                    {
                echo $row['Client'];
                echo $row['Total Due'];
                echo $row['Credit Total Due'];
                echo $row['Cash Total Due'];
                    }

Answer 1

你可以使用类似的东西：

SELECT `client_name` As `Client`,
SUM(`due_to_client`) As `Total Due`,
SUM(CASE WHEN `paymenttype`='Credit' THEN `due_to_client` ELSE 0 END) As `Credit Total Due`,
SUM(CASE WHEN `paymenttype`='Cash' THEN `due_to_client` ELSE 0 END) As `Cash Total Due`
FROM `Consignment` 
WHERE `payout_approved` = 'Yes' 
GROUP BY `client_name`

这应该会产生结果：

Client | Total Due | Credit Total Due | Cash Total Due

当然，尽量避免使用 mysql_* 扩展，而这在 mysql 5.5.x 中已被弃用。而是使用 mysqli 或 pdo 扩展名