Table

ForAll

Runs a formula for every record in a table and returns a table of the results.

Syntax

ForAll(Table, Formula)

ForAll(colCart, Patch(OrderLines, Defaults(OrderLines), { Product: ThisRecord.Product, Qty: ThisRecord.Qty }))

Saves each cart line

Use ThisRecord to refer to the current record.
Records are not guaranteed to run in order. Avoid changing the same table you are looping over.