What is the difference between clustered and nonclustered in SQL Server

CLUSTERED: Clustered index. Nonclustered index: nonclustered.

Clustered is the physical implementation of data ordering, and the same table can only have one clustered index, and nonclustered is the logical sort.

Microsoft's SQL Server supports two types of indexes: Clustered index and nonclustered index.

The clustered index stores data in a data table in a physical order. Because there is only one physical order in a table, there can be only one clustered index in each table. When looking for data in a range, the clustered index is a very efficient index because the data is sorted in a physical order when it is stored.

The nonclustered index does not affect the following physical storage, but it is composed of data row pointers. If an clustered index already exists, the index pointer in nonclustered will contain the position reference of the clustered index. These indexes are more jincu than the data, and they are scanned much faster than the actual datasheet scans.

PRIMARY KEY constraint defaults to Clustered;unique constraint default to nonclustered.

See more highlights of this column: http://www.bianceng.cnhttp://www.bianceng.cn/database/SQLServer/