php+mysql多重查询值求和

Question

$cbumen = mysqli_query($daohang, 'SELECT * FROM baa WHERE bumen=1);

while($row = mysqli_fetch_array($cbumen)){

$qudaoma=$row['qudaoma'];
$jr = mysqli_query($conn, 'SELECT * FROM kh WHERE user_id='.$qudaoma.' ');
$jrtj=mysqli_num_rows($jr);

echo $jrtj;

 }

因为$qudaoma 有多个值，比如有五个值，那么输出的$jrtj就有五个值，如果才能输出$jrtj的和、

Answer 1

在while遍历一次累加要求和的字段

$cbumen = mysqli_query($daohang, 'SELECT * FROM baa WHERE bumen=1);
while($row = mysqli_fetch_array($cbumen)){

$qudaoma=$row['qudaoma'];
$jr = mysqli_query($conn, 'SELECT * FROM kh WHERE user_id='.$qudaoma.' ');
$jrtj=0;
while($rjrow = mysqli_fetch_array($jr)){
$jrtj=$rjrow["要求和的字段名"];
}
echo $jrtj;
 }

或者直接sql求和

$cbumen = mysqli_query($daohang, 'SELECT * FROM baa WHERE bumen=1);
while($row = mysqli_fetch_array($cbumen)){

$qudaoma=$row['qudaoma'];
$jr = mysqli_query($conn, 'SELECT sum(要求和的字段名) as total FROM kh WHERE user_id='.$qudaoma.' ');

$rjrow = mysqli_fetch_array($jr);
$jrtj=$rjrow["total"];

echo $jrtj;
 }