If it's just adding to a certain character's skillset it's pretty easy, just
Code:
INSERT INTO [Telecaster].[dbo].[Skill]
([SID]
,[OWNER_ID]
,[JP_DEC]
,[SUMMON_ID]
,[SKILL_ID]
,[SKILL_LEVEL]
,[COOL_TIME])
VALUES
(<SID, int,>
,<OWNER_ID, int,>
,<JP_DEC, int,>
,<SUMMON_ID, int,>
,<SKILL_ID, int,>
,<SKILL_LEVEL, int,>
,<COOL_TIME, int,>)
GO
Just substitute the things between <>s
If it's adding to a skilltree, I don't think it's possible from just the database.