Right. Make sure the _Enemy column is defined somewhere. The easiest way to do this for a dynamically-created database (one that's added to when needed, rather than being declared in the INIT section) is to use a procedure, as this will set up the correct types with the compiler:

Code
PROC
MonkWorks_AddEnemy((STRING)_Type, (CHARACTERGUID)_Enemy)
THEN
DB_MonkWorks_SpawnedEnemies(_Type, _Enemy);

IF
StoryEvent((CHARACTERGUID)_Player, "MonkWorks_Events_CreateEnemy_Zone1")
AND
TemporaryCharacterCreateOutOfSightToObject("MonkWorks_Enemy_Ghoul01_36662d44-3f2b-4f50-bfe3-99fe5203090e", _Player, ITEMGUID_SpawnPortalGlow_Zone1_6e363764-eb26-4b49-98a8-df99d6965049, 1, "MonkWorks_Events_GhoulCreated", _Ghoul)
AND
CharacterGetLevel(_Player, _PlayerLevel)
THEN
CharacterLevelUpTo(_Ghoul, _PlayerLevel);
MonkWorks_AddEnemy("Ghoul", _Ghoul);