MS SQL插入与选择

Question

以下是使用SQL查询插入选择，这是不工作，请与问题的帮助：

insert into Area Values (AreaId, AreaName, Pincode, CityId, StateId, CountryId) 
    select CityId 
    from Area 
     join City On Area.CityId = City.CityId 
     Join State on Area.StateId = State.StateId 
     join Country on Area.CountryId = Country.CountryId; 

Answer 1

什么是该查询的目的是什么？您正在与其他人加入目标表（Area）并尝试插入它，这是数据已在Area表中显示的标记，并且您正在插入重复项或试图更新现在为空的列。在这种情况下，您需要合并甚至更新。

UPDATE A 
SET CityID = c.CityID, 
    StateID = s.StateID, 
    CountryID = co.CountryID 
from Area a 
join City c 
    On a.CityId = c.CityId 
Join State s 
    on a.StateId = s.StateId 
join Country co 
    on a.CountryId = co.CountryId; 

如果正是你需要插入 - 指定一个像下面的所有列：

insert into Area Values (AreaId, AreaName, Pincode, CityId, StateId, CountryId) 
select a.AreaID, 
     a.AreaName, 
     a.Pincode, 
     c.CityID, 
     s.StateID, 
     co.CountryID 
from Area a 
join City c 
    On a.CityId = c.CityId 
Join State s 
    on a.StateId = s.StateId 
join Country co 
    on a.CountryId = co.CountryId; 

编辑：

insert into Area Values (AreaId, AreaName, Pincode, CityId, StateId, CountryId) 
select a.AreaID, 
     a.AreaName, 
     a.Pincode, 
     c.CityID, 
     s.StateID, 
     co.CountryID 
from Area a 
LEFT join City c 
    On c.CityName = @CityName 
LEFT Join State s 
    on s.StateName = @StateName 
LEFT join Country co 
    on co.CountryName = @CountryName; 

凡@CityName，@StateName，@CountryName是变量存储从下拉列表数据。