sql语句优化： 1。表加索引 2。少用like,直接用=所有值 3. where语句把能大量筛查的条件写在前面 4.数据量大时，参与计算的值相同时只取一条 后一条减前一条， select houec,[houdate],houtimes ,tw=ISNULL(convert(decimal(18,2),houtw-(select top 1 qiant
sql语句优化：
1。表加索引
2。少用like,直接用=所有值
3.where语句把能大量筛查的条件写在前面
4.数据量大时，参与计算的值相同时只取一条
后一条减前一条，，
select houec,[houdate],houtimes
,tw=ISNULL(convert(decimal(18,2),houtw-(select top 1 qiantw from #qian where houec=qianec and houcid>qiancid order by qiancid desc)),0)
,mins=isnull(DATEDIFF (minute ,(select top 1 qiandatetimes from #qian where houec=qianec and houcid>qiancid order by qiancid desc),houdatetimes),0)
from #hou
其中：
1 临时表#hou与#qian为同一个表中的数据，为方便计算写入两个临时表；
2 ec为设备编号，id为表的ID号，相同的设备中id号唯一，houec=qianec and houcid>qiancid 限定了相同设备中相临ID号的记录相减。
select top 1 qiantw from #qian where houec=qianec and houcid>qiancid order by qiancid desc
为查询houec=qianec 而且houcid>qiancid相同设备中相临ID号的记录相减
日报
drop table #qian
CREATE TABLE #qian(qiancid nvarchar(20),qianec nvarchar(20) null, qiandatetimes smalldatetime null, qiandate datetime null,
qiantimes varchar(20) null,qiantw float null,
CONSTRAINT [PK_Electricqian] PRIMARY KEY CLUSTERED
(
[qiancid] ASC
)WITH (PAD_INDEX = OFF, STATISTICS_NORECOMPUTE = OFF, IGNORE_DUP_KEY = OFF, ALLOW_ROW_LOCKS = ON, ALLOW_PAGE_LOCKS = ON) ON [PRIMARY]
) ON [PRIMARY]
INSERT INTO #qian
select min(cid) as qiancid,cequipmentcode as qianec,
min(dateadd(hh,0,convert(SMALLDATETIME,(cdate+' '+ctime),120)))as qiandatetimes ,
convert(varchar(10),dateadd(hh,0,convert(SMALLDATETIME,(cdate+' '+ctime),120)),120) as qiandate,
str(datepart(hh,dateadd(hh,0,convert(SMALLDATETIME,(cdate+' '+ctime),120)))) + ':00' as qiantimes,
cast(ctotalyield as float) as qiantw
from InverterData_201310
where convert(varchar(10),dateadd(hh,0,convert(SMALLDATETIME,(cdate+' '+ctime),120)),120) = '2013-11-12' and ctotalyield<>'na' and ctotalyield<>'' and ctotalyield is not null and ctotalyield<>'0' and ctotalyield<>'#INV#' and ctotalyield<>'nan'
group by cequipmentcode,convert(varchar(10),dateadd(hh,0,convert(SMALLDATETIME,(cdate+' '+ctime),120)),120),datepart(hh,dateadd(hh,0,convert(SMALLDATETIME,(cdate+' '+ctime),120))),ctotalyield
UNION select min(cid) as qiancid,cequipmentcode as qianec,
min(dateadd(hh,0,convert(SMALLDATETIME,(cdate+' '+ctime),120)))as qiandatetimes ,
convert(varchar(10),dateadd(hh,0,convert(SMALLDATETIME,(cdate+' '+ctime),120)),120) as qiandate,
str(datepart(hh,dateadd(hh,0,convert(SMALLDATETIME,(cdate+' '+ctime),120)))) + ':00' as qiantimes,
cast(ctotalyield as float) as qiantw
from InverterData_201311
where convert(varchar(10),dateadd(hh,0,convert(SMALLDATETIME,(cdate+' '+ctime),120)),120) = '2013-11-12' and ctotalyield<>'na' and ctotalyield<>'' and ctotalyield is not null and ctotalyield<>'0' and ctotalyield<>'#INV#' and ctotalyield<>'nan'
group by cequipmentcode,convert(varchar(10),dateadd(hh,0,convert(SMALLDATETIME,(cdate+' '+ctime),120)),120),datepart(hh,dateadd(hh,0,convert(SMALLDATETIME,(cdate+' '+ctime),120))),ctotalyield
UNION select min(cid) as qiancid,cequipmentcode as qianec,
min(dateadd(hh,0,convert(SMALLDATETIME,(cdate+' '+ctime),120)))as qiandatetimes ,
convert(varchar(10),dateadd(hh,0,convert(SMALLDATETIME,(cdate+' '+ctime),120)),120) as qiandate,
str(datepart(hh,dateadd(hh,0,convert(SMALLDATETIME,(cdate+' '+ctime),120)))) + ':00' as qiantimes,
cast(ctotalyield as float) as qiantw
from InverterData_201312
where convert(varchar(10),dateadd(hh,0,convert(SMALLDATETIME,(cdate+' '+ctime),120)),120) = '2013-11-12' and ctotalyield<>'na' and ctotalyield<>'' and ctotalyield is not null and ctotalyield<>'0' and ctotalyield<>'#INV#' and ctotalyield<>'nan'
group by cequipmentcode,convert(varchar(10),dateadd(hh,0,convert(SMALLDATETIME,(cdate+' '+ctime),120)),120),datepart(hh,dateadd(hh,0,convert(SMALLDATETIME,(cdate+' '+ctime),120))),ctotalyield
drop table #hou
CREATE TABLE #hou(houcid nvarchar(20),houec nvarchar(20) null,houdatetimes smalldatetime null, houdate smalldatetime null,houtimes varchar(20) null,houtw float null,
CONSTRAINT [PK_Electrichou] PRIMARY KEY CLUSTERED
(
[houcid] ASC
)WITH (PAD_INDEX = OFF, STATISTICS_NORECOMPUTE = OFF, IGNORE_DUP_KEY = OFF, ALLOW_ROW_LOCKS = ON, ALLOW_PAGE_LOCKS = ON) ON [PRIMARY]
) ON [PRIMARY]
INSERT INTO #hou
select min(cid) as houcid,cequipmentcode as houec,min(dateadd(hh,0,convert(SMALLDATETIME,(cdate+' '+ctime),120)))as houdatetimes ,convert(varchar(10),dateadd(hh,0,convert(SMALLDATETIME,(cdate+' '+ctime),120)),120) as houdate,
str(datepart(hh,dateadd(hh,0,convert(SMALLDATETIME,(cdate+' '+ctime),120)))) + ':00' as houtimes,
cast(ctotalyield as float) as houtw
from InverterData_201310
where convert(varchar(10),dateadd(hh,0,convert(SMALLDATETIME,(cdate+' '+ctime),120)),120)='2013-11-12' and ctotalyield<>'na' and ctotalyield<>'' and ctotalyield is not null and ctotalyield<>'0' and ctotalyield<>'#INV#' and ctotalyield<>'nan'
group by cequipmentcode,convert(varchar(10),dateadd(hh,0,convert(SMALLDATETIME,(cdate+' '+ctime),120)),120),datepart(hh,dateadd(hh,0,convert(SMALLDATETIME,(cdate+' '+ctime),120))),ctotalyield
UNION
select min(cid) as houcid,cequipmentcode as houec,min(dateadd(hh,0,convert(SMALLDATETIME,(cdate+' '+ctime),120)))as houdatetimes ,convert(varchar(10),dateadd(hh,0,convert(SMALLDATETIME,(cdate+' '+ctime),120)),120) as houdate,
str(datepart(hh,dateadd(hh,0,convert(SMALLDATETIME,(cdate+' '+ctime),120)))) + ':00' as houtimes,
cast(ctotalyield as float) as houtw
from InverterData_201311
where convert(varchar(10),dateadd(hh,0,convert(SMALLDATETIME,(cdate+' '+ctime),120)),120)='2013-11-12' and ctotalyield<>'na' and ctotalyield<>'' and ctotalyield is not null and ctotalyield<>'0' and ctotalyield<>'#INV#' and ctotalyield<>'nan'
group by cequipmentcode,convert(varchar(10),dateadd(hh,0,convert(SMALLDATETIME,(cdate+' '+ctime),120)),120),datepart(hh,dateadd(hh,0,convert(SMALLDATETIME,(cdate+' '+ctime),120))),ctotalyield
UNION
select min(cid) as houcid,cequipmentcode as houec,min(dateadd(hh,0,convert(SMALLDATETIME,(cdate+' '+ctime),120)))as houdatetimes ,convert(varchar(10),dateadd(hh,0,convert(SMALLDATETIME,(cdate+' '+ctime),120)),120) as houdate,
str(datepart(hh,dateadd(hh,0,convert(SMALLDATETIME,(cdate+' '+ctime),120)))) + ':00' as houtimes,
cast(ctotalyield as float) as houtw
from InverterData_201312
where convert(varchar(10),dateadd(hh,0,convert(SMALLDATETIME,(cdate+' '+ctime),120)),120)='2013-11-12' and ctotalyield<>'na' and ctotalyield<>'' and ctotalyield is not null and ctotalyield<>'0' and ctotalyield<>'#INV#' and ctotalyield<>'nan'
group by cequipmentcode,convert(varchar(10),dateadd(hh,0,convert(SMALLDATETIME,(cdate+' '+ctime),120)),120),datepart(hh,dateadd(hh,0,convert(SMALLDATETIME,(cdate+' '+ctime),120))),ctotalyield
