PHP Internal Website inserting data into SQL Database

I need to link a table in a PHP website to my MSSQL Database.

The website is a form of warehouse management and the purpose of what I am trying to do is so the Warehouse staff can can print order(s) at will and in batches from the website rather than having to go into the ERP system and manually print each one individually.

I am trying to set it up so that in a table on the website, you tick checkboxes of lines with the order numbers on and then click a print button.

Upon clicking the print button it queries which lines are ticked, selects the corresponding order numbers and a print field populated with "Y", and then inserts them into a staging table in the database.

At which point I then already have some automation to look at this table and print off the orders accordingly.

The table on the website is complete with the SQL to populate the lines, the checkboxes and the button but I just need assistance in writing the code which tells the website to insert the data lines into the database at the point of clicking the Button as I can't seem to get this to work.

Also I would like whoever may help me on this to add in comments on lines they have edited to explain what has been done so I can better understand where I have gone wrong.

Files will be uploaded at point of contact of the project along with answers to any questions you may have.

Thanks.