Save data from a php page into 2 sql table - php

Question

Good day!I really need your help guys. Can someone teach me what statements I need to save data into 2 tables. I have 2 tables namely sales and sales_item. The relationship bet. them is the srfno where in sales table it is the PK, so in sales_item table it is the FK. My php form has srfno, date, clientid, clientname, address, contactperson, contactno, returnreason, explanation, refno; these data should be saved in sales table which I already did and it's working brilliantly. My problem now is that qty, serial, desc also include in the form but these should be saved in sales_item table. When I execute the page, it saves the data in sales table and the qty, serial and desc can't save to sales_item table and it didn't get the srfno from sales table.
here's my code for saving qty, serial and desc to sales_item table which is being ignored by my sql statement when saving.
$retitem= "Select `srfno` from sales_item";
$psql= mysql_query($retitem,$con);
$reti = mysql_num_rows($psql);
$reti = $reti + 1;
while($return = mysql_fetch_assoc($psql))
{
if(isset($return['srfno']))
{
$srfno=$return['srfno'];
}
}
$addretex="Insert into `sales_item` (`sitemid`,`srfno`, `retqty`, `retdesc`,`retserial`, `exqty`, `exdesc`,`exserial`,)
VALUES (' ','$srfno', '$qty', '$desc', '$serialno', ' ', ' ', ' ')";
$ret=mysql_query($addretex);

Answer 1

easily you can use LAST_INSERT_ID to insert your last 3 values into table sales_item with related sales id.
INSERT INTO sales (srfno,date,clientid,clientname,address,contactperson,contactno, returnreason,explanation,refno)
VALUES('value1', 'value2','','',...);
INSERT INTO sales_item (sales_id,qty,serial,desc) //sales_id is foreign key came from sales table and its value will be insert automatically by using LAST_INSERT_ID.
VALUES(LAST_INSERT_ID(),'value_1', 'value_2','value_3');

Answer 2

Before Inserting into 'sales_item', you need to check whether $srfno has valid value using
echo "srfno=".$srfno;exit;
if not, you can easily get value of $srfno after inserting into sales table, just do following after inserting into sales table
$srfno=mysql_insert_id();
You can also check error of insert query of sales_item by mysql_error function
mysql_query($addretex) or die("$addretex ".mysql_error());