← Inventory & Replenishment Exceptions
Lesson 1 of 4
Separate unknown stock from zero
Identify counts that need investigation before ordering.
Do the work
- NULL on_hand means the physical count is unknown. Zero means the count is known to be zero.
- Subtract reserved units only from a known physical count.
- A negative available count is a reservation conflict; do not silently convert it to zero.
See the method
NULL - 3 stays NULL.
Read every demonstration step
- NULL - 3 stays NULL.
- 0 - 0 is a known zero and can trigger a reorder.
- 1 - 4 is -3 and needs a reservation review first.
Practice independently
Exercise 1
List products needing a physical count
Open practice →Exercise 2Calculate available units
Open practice →Take it further
Check how a blanket COALESCE(on_hand,0) would create unjustified purchase orders.