When you exclude data from the first table, modify the value of the related field in the second table

When you delete data from the first table, modify the value of the related field in the second table
Table XF
XF_ID VIP Total
1 1 10
2 1 100
3 2 80
4 3 50


Table VIP
VIP Jifen
1 1000
2 500
3 800

$sql = "Delete from". $fdyu->table (' XF ').
"WHERE xf_id". Db_create_in (Join (', ', $_post[' checkboxes ')). If $_post[' checkboxes ' is xf_id:1,2,3,4
"and school_id=". $school _id;
$db->query ($sql);

So while deleting xf_id, the table VIP
1 jifen=1000-110=890 If the XF has more than one VIP, subtract the sum, such as the XF table VIP 1 has two data, their total and is 110,
Then minus 110.
2 jifen=500-80=420
3 jifen=800-50=750
That is, while deleting the data from the table XF, the Jifen in the table VIP will subtract the total from the XF
------Solution--------------------
Approximate idea

1. First get the VIP to delete the record, and the total score of each VIP deleted
Select Vip,sum (total) from the XF where xf_id in (1,2,3,4) group by VIP;
Save As Array
VIP is key
Total is value

$arr = Array (
' 1 ' = 110,
' 2 ' = 80,
' 3 ' = 50
);

2. Delete the records for the corresponding xf_id
Delete from the XF where xf_id in (1,2,3,4);

3. Modify the VIP Table
foreach ($arr as $vip = = $total) {
Update VIP set jifen=jifen-$total where vip= $VIP
}

------Solution--------------------
You can consider using a trigger, in MySQL execution, to give you an example:

Create   trigger   delete_jifen   before delete   on   jifen
  For   each   row  
BEGIN
UPDATE Users  
(SELECT sum (jifen.jifen) from Jifen where Jid = Old.jid) where Users.userid = Old.userid;
END

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