Select Basics

Select CASE ELSE NULL

When no CASE condition is TRUE and ELSE is omitted, the result is NULL.

highlighted = computed this step

Input table

Start with shipment rows and late-day counts.

Shipments\text{Shipments}
Shipmentsorder_idstatusdays_lateo1late3o2on_time0o3late8

Select query

Return an action only when the CASE condition is TRUE.

CASE without ELSE\text{CASE without ELSE}
SELECT CASE with omitted ELSEselect order_id,late_actionarity 2 rows 3Shipmentsarity 3 rows 3

Output table

Rows without a TRUE condition get NULL because ELSE is omitted.

conditional action\text{conditional action}
Outputorder_idlate_actiono1NULLo2NULLo3escalate