diff --git a/src/main/kotlin/com/reinsteinquizbowl/order/repository/BookingRepository.kt b/src/main/kotlin/com/reinsteinquizbowl/order/repository/BookingRepository.kt
index 6a25621..1a3ffe6 100644
--- a/src/main/kotlin/com/reinsteinquizbowl/order/repository/BookingRepository.kt
+++ b/src/main/kotlin/com/reinsteinquizbowl/order/repository/BookingRepository.kt
@@ -16,10 +16,4 @@ interface BookingRepository : CrudRepository<Booking, Long> {
         nativeQuery = true
     )
     fun countLowerIdBookingsForSchoolId(schoolId: Long, bookingId: Long): Long
-
-    @Query(
-        "select count(*) from booking where school_id is null and id < ?1",
-        nativeQuery = true
-    )
-    fun countLowerIdBookingsForNoSchool(bookingId: Long): Long
 }
diff --git a/src/main/kotlin/com/reinsteinquizbowl/order/service/Converter.kt b/src/main/kotlin/com/reinsteinquizbowl/order/service/Converter.kt
index 4513680..065a882 100644
--- a/src/main/kotlin/com/reinsteinquizbowl/order/service/Converter.kt
+++ b/src/main/kotlin/com/reinsteinquizbowl/order/service/Converter.kt
@@ -58,7 +58,7 @@ class Converter {
 
         return ApiBooking(
             id = entity.id,
-            school = entity.school?.let { toApi(it) },
+            school = toApi(entity.school!!),
             name = entity.name,
             emailAddress = entity.emailAddress,
             authority = entity.authority,
diff --git a/src/main/kotlin/com/reinsteinquizbowl/order/service/InvoiceCalculator.kt b/src/main/kotlin/com/reinsteinquizbowl/order/service/InvoiceCalculator.kt
index caf6be4..16afa45 100644
--- a/src/main/kotlin/com/reinsteinquizbowl/order/service/InvoiceCalculator.kt
+++ b/src/main/kotlin/com/reinsteinquizbowl/order/service/InvoiceCalculator.kt
@@ -40,18 +40,12 @@ class InvoiceCalculator {
     @Autowired private lateinit var invoiceLineRepo: InvoiceLineRepository
 
     fun determineInvoiceLabel(booking: Booking): String {
-        val schoolId = booking.school?.id
+        val schoolId = booking.school!!.id!!
 
-        val bookingsWithLowerId = if (schoolId == null) {
-            repo.countLowerIdBookingsForNoSchool(booking.id!!)
-        } else {
-            repo.countLowerIdBookingsForSchoolId(schoolId, booking.id!!)
-        }
+        val bookingsWithLowerId = repo.countLowerIdBookingsForSchoolId(schoolId, booking.id!!)
         val thisBookingSequence = bookingsWithLowerId + 1
 
-        val displayableSchoolId = schoolId?.toString() ?: "X"
-
-        return "$displayableSchoolId-$thisBookingSequence"
+        return "$schoolId-$thisBookingSequence"
     }
 
     // This logic is described in the UI, so when updating it, it should be updated in both places.
diff --git a/src/main/resources/db/creation.sql b/src/main/resources/db/creation.sql
index af98c10..f0ca10b 100644
--- a/src/main/resources/db/creation.sql
+++ b/src/main/resources/db/creation.sql
@@ -69,7 +69,7 @@ create table booking_status (
 -- I wanted to call this `order`, but that's a SQL reserved word
 create table booking (
     id serial primary key,
-    school_id int null references school,
+    school_id int not null references school,
     name text not null,
     email_address text not null,
     authority text null,