(1)同一张表中可能存在多辆车的皮重记录，想更新最早的一条记录，即更新其皮重。在sqlite3中，如下：
update CarNoTable set TareWeight ='9080' - where CarNO='京A6390' and TareWeight = - (select TareWeight from CarNoTable where CarNo='京A6390' - order by TareTime limit 0,5 )
CarNoTable:表
TareWeight:皮重字段
CarNo:车号
TareTime:皮重时间
(2)将字符串字段转成整数,并以此找到最大的一条记录。如同一车辆的多个皮重记录，想找出最大的一次记录。
Select max(cast(TareWeight as FLOAT)) from CarNoTable where CarNo = '京A6390'
(3)查看最大皮重值及时间
select CarNo, TareWeight,TareTime from CarNoTable where cast(TareWeight as FLOAT) in (select max(cast(TareWeight as FLOAT)) from CarNoTable where CarNo='京A00A01')
