Vsro Weapon Upgrade System (query used to do )

Declare 
@maxserial BIgINT = (select MAX(serial64)from _Items)+1,
@RefItemID BIGINT,
@UpgradeItemCodeName VARCHAR (70),
@Data BigInt,
@maxID64 BIgINT = (select MAX(ID64)from _Items)+1,
@Optlevel INT ,
@Check_Correct VARCHAR (40)

IF NOT EXISTS (select UserJID From _Chest where UserJID IN (select UserJID from _User where CharID IN (select CharID from _Memo where Message like '%Upgrade%My%SWORD%')))
Begin
PRINT 'No one want to Upgrade a SWORD'
End
IF EXISTS (select UserJID From _Chest where UserJID IN (select UserJID from _User where CharID IN (select CharID from _Memo where Message like '%Upgrade%My%SWORD%')))
Begin
if not exists (select Message from _Memo where Message like '%Upgrade%My%SWORD%' and CharID IN(select CharID from _User where UserJID IN (select UserJID from _Chest where ItemID IN (select ID64 from _Items where RefItemID = (select ID from _RefObjCommon where CodeName128 = 'ITEM_CH_SWORD_11_SET_A_RARE')))))
begin
print 'Not working'
end
if exists (select Message from _Memo where Message like '%Upgrade%My%SWORD%' and CharID IN(select CharID from _User where UserJID IN (select UserJID from _Chest where ItemID IN (select ID64 from _Items where RefItemID = (select ID from _RefObjCommon where CodeName128 = 'ITEM_CH_SWORD_11_SET_A_RARE')))))
begin
if exists (select ItemID from _Chest where ItemID IN (select ID64 from _Items where RefItemID = (select ID from _RefObjCommon where CodeName128 = 'ITEM_CH_SWORD_11_SET_A_RARE')))
Begin
UPDATE _Chest SET Type = 'SWORD_SET_A_11' where ItemID IN (select ID64 from _Items where RefItemID = (select ID from _RefObjCommon where CodeName128 = 'ITEM_CH_SWORD_11_SET_A_RARE'))
Set @Optlevel =(select OptLevel from _Items where OptLevel > '7' and ID64 IN (select ItemID from _Chest where Type = 'SWORD_SET_A_11'))
IF @Optlevel > 7
Begin
UPDATE _Chest set ItemID = NULL where Type = 'SWORD_SET_A_11' and UserJID IN (select UserJID from _User where CharID IN (select CharID from _Memo where [Message] like '%Upgrade%My%SWORD%'))
UPdAte _Chest Set Type = 'SWORD_SET1_A_11' where type = 'SWORD_SET_A_11'
IF EXISTS (select Type from _Chest where Type = 'SWORD_SET1_A_11')
SET IDENTITY_INSERT _items ON
SET @UpgradeItemCodeName = 'ITEM_CH_SWORD_12_C_RARE'
SET @RefItemID = (select ID from _RefObjCommon where CodeName128 = @UpgradeItemCodeName)
SET @Data = (select Dur_L from _RefObjItem where ID = ( select Link from _RefObjCommon where CodeName128 =@UpgradeItemCodeName ))
INSERT INTO _Items (ID64, RefItemID, OptLevel, Variance, Data, CreaterName, MagParamNum, MagParam1, MagParam2, MagParam3, MagParam4, MagParam5, MagParam6, MagParam7, MagParam8, MagParam9, MagParam10, MagParam11, MagParam12, Serial64) VALUES (@maxID64,@RefItemID,0,0,@Data,NULL,0,0,0,0,0,0,0,0,0,0,0,0,0,@maxserial)
SET IDENTITY_INSERT _items OFF
INSERT INTO _ItemPool (ItemID,InUse)
VALUES (@maxID64,1)
END
UPDATE _Chest SET ItemID = @maxID64 where Type = 'SWORD_SET1_A_11'
UPDATE _Chest SET type = NULL where TYpe = 'SWORD_SET1_A_11'
UPDATE _Memo SET Message = 'Your SWORD has been Upgraded' where Message like '%Upgrade%My%SWORD%'
IF NOT EXISTS (select OptLevel from _Items where OptLevel > '8' and ID64 IN (select ItemID from _Chest where Type = 'SWORD_SET_A_11'))
Begin
update _Memo set Message = 'Well the process stoped for one of those reasones