Added in house invoice numbering to database triggers IO-460

hasura/migrations/1608741063718_run_sql_migration/down.yaml

@@ -0,0 +1 @@
+[]

hasura/migrations/1608741063718_run_sql_migration/up.yaml

@@ -0,0 +1,6 @@
+- args:
+    cascade: true
+    read_only: false
+    sql: "create trigger bills_assign_ihbnum before\r\ninsert\r\n    on\r\n    public.bills
+      for each row execute procedure assign_ibh_number();"
+  type: run_sql