SQL多表合并,难度问题,想挑战的来!

表1的SQL

select
wsm_datahead.gettime as gettime,wsm_data_3.dataid as datid,wsm_data_3.data1 as datasw
from
wsm_data_3,wsm_DataBlock,wsm_datahead
WHERe
wsm_data_3.DataBlockID=wsm_DataBlock.DataBlockID
and
wsm_DataBlock.dataheadid=wsm_datahead.dataheadid
and
MHID=1112

表2的SQL

合并的条件是

表1的on wsm_datahead.gettime as gettime 的时间大概时间等于表2的wsm_datahead.gettime as gettime2时间误差不多于1个小时左右就合并显示为一条数据

显示的格式为

wsm_data_3 asdataid,wsm_data_3.data1 as datasw,data_7.data1 as databg,wsm_datahead.gettime

如果大家没看清楚了提示下其实这里涉及4个表.

问题补充  2010-08-12 11:46

表2的SQL没贴上补贴

select
wsm_datahead.gettime as gettime2,wsm_data_7.dataid as datid2,wsm_data_7.data1 as databt
from
wsm_data_7,wsm_DataBlock,wsm_datahead
WHERe
wsm_data_7.DataBlockID=wsm_DataBlock.DataBlockID
and
wsm_DataBlock.dataheadid=wsm_datahead.dataheadid
and
MHID=1112

表1、表2...如果查询出来字段一样可以使用union all，最好贴三个表的数据截图，然后写条件及要的结果

union all