Inserting data into multiple tables in PHP

Inserting data into multiple tables in PHP
Table: order_table
Fields: order_id, (table:) rem_table.rem_id (primary key), Order_number
Table: deal_table
Fields: deal_id, order_id, Deal_date, Deal_information, Deal_man

Insert data into these two tables: Order_number, Deal_date, Deal_information, Deal_man

What should I do? where the data is inserted, the field rem_table.rem_id cannot be empty, because in the future to query the data, to be used, (rem_table and order_table query)

------Solution--------------------
First use if to determine, and then insert.

If ()
｛
insert into ();
Mysql->query ();
Inser into ();
Mysql->query ();
｝
Else
{
}
------Solution--------------------
The order table is the "father" of the deal table (according to the design of your table)
So it's all first. (insert) Order and then (insert) deal
Options available for both options
1. Insert Order② query Order_id③ insert deal with database self-increment ①
2.ID Insert Order (write the generated ID directly) ② insert deal with PHP build ①

In Method 2, note that the ID must have some complexity, as we create the image name can not be repeated

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