环境sqlite 和CppSQLite3Query 库
联表使用
select BIDConfig.[Describe] ,BIDData.* from BIDData,BIDConfig where BIDData.[SampleTime] in (select max(BIDData.SampleTime) from BIDData group by GatewayID,NodeID) and BIDData.[NodeID]=BIDConfig.[NodeID] and BIDData.[GatewayID]=BIDConfig.[GatewayID] order by BIDData.[GatewayID]
以上能正常获取Describe字段
如果将order by 之前二次分组时如下
select BIDConfig.[Describe] ,BIDData.* from BIDData,BIDConfig where BIDData.[SampleTime] in (select max(BIDData.SampleTime) from BIDData group by GatewayID,NodeID) and BIDData.[NodeID]=BIDConfig.[NodeID] and BIDData.[GatewayID]=BIDConfig.[GatewayID] group by BIDConfig.[GatewayID] order by BIDData.[GatewayID]
增加了 order by 之前的 group by 在Exper personal 里面能正常显示出来Describe字段
在使用CppSQLite3Query的fieldIndex返回是-1,是不是我使用的库有问题呢CppSQLite3.h的封装库。有各位知道是怎么回事吗? 这库不支持二次分组吗?
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举例说明要达到什么目的?取每组最大?
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贴建表及插入记录的SQL,及要求结果出来看看