select fitemid from t_ICItem union select fitemid from ICInventory
–联合2张表去除重复记录
select fitemid from t_ICItem union all select fitemid from ICInventory
–联合2张表不去除重复记录
select fitemid from t_ICItem intersect select fitemid from ICInventory
–联合2张表仅显示重复记录
select fitemid from t_ICItem t1 where t1.fitemid not in (select fitemid from ICInventory)
–联合2张表仅显示不在ICInventory中的记录