OPENQUERY(linked_server,'query') 其中linked_server参数为连接的名称。而query参数为要进行的查询,它将以一个字符串的形式传送给OPENQUERY函数。此函数返回的将是一个虚拟表,从而可以让我们对其做进一步的查询。 下面的语句查找内容包含中SQL这个单词的所有文件: SELECT* FROMOpenQuery(FileSystem, 'SELECT Directory, ...
(*) AS COUNT FROM Sales.SalesOrderDetail AS od, Sales.SalesOrderHeader AS o WHERE od.SalesOrderID = o.SalesOrderID GROUP BY OrderDate, ProductID; GO -- Create an index on the view CREATE UNIQUE CLUSTERED INDEX IDX_V1 ON Sales.vOrders (OrderDate, ProductID); GO -- This query can ...
To see which indexes the query optimizer uses for a specific query, in SQL Server Management Studio, on the Query menu, select Include Actual Execution Plan.Don't always equate index usage with good performance, and good performance with efficient index use. If using an index always help...
I started SQL recently as a beginner i came across the above problem. the book i referring is using MySQL and i want to know how can i do the following in SQL Server This is the query as per the example in the book SELECT SUBSTRING_INDEX(location, ',', 1) F...
Why is the query optimizer doing an clustered index scan and not a seek? This query is the one existing in an index view. When the index view needs to be updated, is this the actual query that runs to update itself? My thinking was yes, which is why I'm trying to optim...
(*) AS COUNT FROM Sales.SalesOrderDetail AS od, Sales.SalesOrderHeader AS o WHERE od.SalesOrderID = o.SalesOrderID GROUP BY OrderDate, ProductID; GO -- Create an index on the view CREATE UNIQUE CLUSTERED INDEX IDX_V1 ON Sales.vOrders (OrderDate, ProductID); GO -- This query can ...
To see which indexes the query optimizer uses for a specific query, in SQL Server Management Studio, on the Query menu, select Include Actual Execution Plan.Do not always equate index usage with good performance, and good performance with efficient index use. If using an index always helped ...
SQL Graph Sequence numbers Service Broker Spatial data Stored procedures Tables Track changes Triggers User-defined functions Views XML data Development Internals & architecture Installation Migrate & load data Manage, monitor, & tune Query data Reporting & Analytics Security Tools Tutorials SQL Server on...
SQL Graph Sequence numbers Service Broker Spatial data Stored procedures Tables Track changes Triggers User-defined functions Views XML data Development Internals & architecture Installation Migrate & load data Manage, monitor, & tune Query data Reporting & Analytics Security Tools Tutorials SQL Server on...
In This Topic Before you begin: Limitations and Restrictions Security To set the max degree of parallelism, using: SQL Server Management Studio Transact-SQL Before You Begin Limitations and Restrictions The number of processors that are used by the query optimizer typically provides optimal performance...