select * from Person.Person with (nolock)
select * from Person.Person with (index(PK_Person_BusinessEntityID))

select * from Person.Password where BusinessEntityID in (select BusinessEntityID from Person.Person where FirstName='Ken');
--替换为
with tb(BusinessEntityID) as (select BusinessEntityID from Person.Person where FirstName='Ken')
select * from Person.Password where exists(select 1 from tb where BusinessEntityID=Person.Password.BusinessEntityID);

select * from tb where like '%value%' -- like 'value%'
select * from tb where colum1<>0
select * from tb where colum1=1 or colum2=2 --colum1或colum2没有索引则导致全表扫描
--尽量使用exists代替in
select * from tb1 where colum in (select colum from tb2); -- select * from tb1 where exists(select 1 from tb2 where colum=tb1.colum);

select * from tb where datediff(mm,'2015-1-1',colum1)=1;
select * from tb where substring(colum1,1,6)='value';

--join连接最好不要超过5个表，有更新的大数据表先放进临时表，然后再join
select BusinessEntityID,FirstName into #tmptable from Person.Person;
select * from Person.Password,#tmptable where Person.Password.BusinessEntityID=#tmptable.BusinessEntityID
drop table #tmptable

--批量插入数据，select into一定比逐条insert快
insert into tb values(colum1,colum2,colum3),(colum1,colum2,colum3),(colum1,colum2,colum3);
--文件批处理bulk insert和openrowset
https://technet.microsoft.com/zh-cn/library/ms188365(v=sql.105).aspx

create proc proc_xxx
@addressid int,
@city nvarchar(16)
as
begindeclare @sql nvarchar(1148);set @sql='select * from (select *,num=(row_number() over(order by AddressID asc)) from Person.Address where 1=1';if(@city<>'')beginset @sql=@sql+' and City like @city';endif(@addressid<>0)beginset @sql=@sql+' and ID=@addressid';endset @sql=@sql+' ) A where A.num between @sindex and @eindex';exec sp_executesql @sql,N'@city nvarchar(64),@addressid int,@sindex int,@eindex int',@city,@addressid,@sindex,@eindex;
end

set statistics io on
go
select * from Production.WorkOrder where WorkOrderID=1
go
set statistics io off
--表 'WorkOrder'。扫描计数 0，逻辑读取 2 次，物理读取 0 次，预读 0 次，lob 逻辑读取 0 次，lob 物理读取 0 次，lob 预读 0 次。

select  b.name ,  --数据库名称a.statement ,  --缺少索引表的名称a.equality_columns ,  --经常用于等值比较的列名，如 ID=valueinequality_columns ,  --经常用于不等值比较的列名，如 ID>value ID<>valueincluded_columns  --建议在索引中涵盖或者包含的列
from    sys.[dm_db_missing_index_details] ajoin sys.databases b on a.database_id = b.database_id

--更新表索引的统计信息
update statistics tablename with fullscanselectdb_name() as DBNAME,  --数据库名称object_name(a.object_id) as table_name,  --表名称coalesce(name,'object with no clustered index') as index_name, --索引名称type_desc as index_type,  --索引类型user_seeks,  --使用索引查询的次数user_scans,  --使用全表扫描的次数user_lookups,  --使用书签的次数，使用书签会造成二次IO,考虑是否加入非聚集索引user_updates  --索引的更新次数
from sys.dm_db_index_usage_stats a inner join sys.indexes b
on a.index_id = b.index_id  and a.object_id = b.object_id
where database_id = db_id('AdventureWorks2008')