add unique constraint on appointments

src/common/databases/migrations/20230726095252_v25/migration.sql

@@ -0,0 +1,8 @@
+/*
+  Warnings:
+
+  - A unique constraint covering the columns `[user_uid,choice,status]` on the table `appointments` will be added. If there are existing duplicate values, this will fail.
+
+*/
+-- CreateIndex
+CREATE UNIQUE INDEX "appointments_user_uid_choice_status_key" ON "appointments"("user_uid", "choice", "status");

src/common/databases/schema.prisma

@@ -297,6 +297,7 @@ model Appointments {
   status   EAppointmentStatus @default(OPEN)
   votes    Votes[]
 
+  @@unique([user_uid, choice, status])
   @@map("appointments")
 }