Using SQL Server Management Studio To create a nonclustered index by using the Table Designer In Object Explorer, expand the database that contains the table on which you want to create a nonclustered index. Expand theTablesfolder. Right-click the table on which you want to create a nonclust...
在前面的查询中,SQL Server 读取根节点页并检索每个叶节点页和行以进行数据检索。 现在让我们在 SQL Server的EmpContactNumber列上的Employee表上 创建一个唯一的非聚集索引作为索引键: CREATEUNIQUENONCLUSTERED INDEX IX_NonClustered_EmployeeONdbo.Employee(EmpContactNumber); 1 在我们解释这个索引之前,重新运行 SEL...
Using SQL Server Management Studio To create a nonclustered index by using the Table Designer In Object Explorer, expand the database that contains the table on which you want to create a nonclustered index. Expand theTablesfolder. Right-click the table on which you want to create a nonclust...
To create a non-clustered index, you have to use the “CREATE NONCLUSTERED” statement. The rest of the syntax remains the same as the syntax for creating a clustered index. The following script creates a non-clustered index “IX_tblPatient_Name” which sorts the records in ascending order ...
In a relational database every table can have at most one clustered index and many non-clustered index. Though it facilitates fast retrieval of data the cost (in terms of time) of maintaining these indexes after every INSERT, UPDATE and DELETE query increases with the size of the table, ...
CREATE NONCLUSTERED INDEX IX_EMP_NAME ON EMPLOYEES(NAME) -- 再次执行WHERE查询并含实际执行计划。 SELECT * FROM EMPLOYEES WHERE NAME = 'ABC 874000' 1. 2. 3. 4. 5. 6. Key映射查找 查询例子同上。 上例的执行计划中我们可以看到key lookup过程,这个映射查找出现的原因是我们的查询里name字段虽然可以...
SQL Server automatically creates indexes when PRIMARY KEY and UNIQUE constraints are defined on table columns. For example, when you create a table with a UNIQUE constraint, Database Engine automatically creates a nonclustered index. If you configure a PRIMARY KEY, Database Engine automatically creat...
1. 什么是聚合索引(clustered index) / 什么是非聚合索引(nonclustered index)? 2. 聚合索引和非聚合索引有什么区别? 深入浅出理解索引结构 实际上,您可以把索引理解为一种特殊的目录。微软的SQL SERVER提供了两种索引:聚集索引(clustered index,也称聚类索引、簇集索引)和非聚集索引(nonclustered index,也称非聚类...
Memory-optimized nonclustered indexes are a new index type for memory-optimized tables inCTP2. Nonclustered indexes support retrieving ranges of values, and also support retrieving the table rows in the order that was specified when the index was created. They can...
There can beonly one clustered index per table. However, you can create multiple non-clustered indexes on a single table. Clustered indexes only sort tables. Therefore, they do not consume extra storage. Non-clustered indexes are stored in a separate place from the actual table claiming more ...