SqlServer性能优化索引（五）

导入表结构：

select * into ProductCategory from AdventureWorksDW2014.dbo.DimProductCategory
select * into Product from AdventureWorksDW2014.dbo.DimProduct

开启磁盘io：

set statistics io on
select EnglishProductName,StandardCost,Color,Size,Weight from Product
where size>‘M‘--0.189 io:251
set statistics io off

非聚簇索引：

创建的语句：create nonclustered index nc_product_size on product(size)

再次执行上面的查询代码（提高了三倍）：

set statistics io on
select EnglishProductName,StandardCost,Color,Size,Weight from Product
where size>‘M‘   --0.054 io:19
set statistics io off

建立覆盖索引：

create nonclustered index nc_product_size1 on product(size) include(EnglishProductName,
StandardCost,Color,Weight)

再次执行上述语句：

set statistics io on
select EnglishProductName,StandardCost,Color,Size,Weight from Product
where size>‘M‘   --0.003 io:2
set statistics io off

数据库会自动选择索引：