Question

我有两张桌子：

DistrictMaster ：

-----------------------------------------------------
DistrictID     |        DistrictName   |    State
-----------------------------------------------------
    21         |          ABC          |    ktm
    22         |          XYZ          |    ktm
    32         |          PQR          |    johar
-----------------------------------------------------

Districtdetail ：

District      |   DistrciID  | State   | Country  
------------------------------------------------
PQR           |              | johar   |   MY
null          |              | Kedah   |   MY
ABC           |              | ktm     |   MY
              |              | Kedah   |   MY
XYZ           |              | ktm     |   MY
------------------------------------------------

我需要在DistrictID中插入Districtdetail，这些insert into Districtdetail(DistrictID) select a.id from DistrictMaster a left join Districtdetail b on a.DistrictName = b.DistrictName and a.State = b.State;几乎没有值，也没有值。我在查询下面使用但不插入。

uint8_t digest[CC_SHA1_DIGEST_LENGTH];
NSData* data = [stringToHash dataUsingEncoding:NSUTF8StringEncoding];
char* sha = CC_SHA1(data.bytes, data.length, digest);
NSData *hashedData = [NSData dataWithBytes:sha length:CC_SHA1_DIGEST_LENGTH];

以上查询说已执行但未插入任何内容。

Answer 1

这是带join的简单更新语句：

update d
set DistrictID = m.DistrictID
from DistrictMaster m
join Districtdetail d on m.DistrictName = d.District and m.State = d.State

Answer 2

如果连接中未保留主键，则可能会遇到连接更新问题。在这种情况下，您应该尝试以这种方式更新Districtdetail：

update Districtdetail dd
set dd.DistrictID = (select dm.DistrictID 
                       from DistrictMaster dm
                      where dm.DistrictName = dd.District
                        and dm.State = dd.State)
where exists
(select * 
   from DistrictMaster dm
  where dm.DistrictName = dd.District
    and dm.State = dd.State)

null值未插入插入查询

2 个答案: