Some data types use 1 byte per character ; each byte can have 1 of 256 different bit patterns 数据库引擎自动添加到行以使每个索引键保持唯一的4字节列。
Vsam arranges records by an index key , relative record number , or relative byte addressing Vsam通过一个索引键值，相关记录号或者相关字节地址来组织记录。
A unique index is one in which no two rows are permitted to have the same index key value 唯一索引不允许两行具有相同的索引键值。视图的聚集索引必须唯一。
Neither column of the output result set is a key , but together they form an index key 输出结果集中的任一列都不是一个键，但是它们结合在一起将形成一个索引键。
It also provides the names of the columns that should be used for the index key 此查询提供缺失索引的数据库、架构和表的名称。它还提供应该用于索引键的列的名称。
This occurs because the key columns for indexes that the missing indexes feature recommends are not order - sensitive 这是因为缺失索引功能建议的索引键列不区分先后顺序。
They are not considered by the database engine when calculating the number of index key columns or index key size 在计算索引键列数或索引键大小时，数据库引擎不考虑它们。
A clustered index sorts and stores the data rows of the table or view in order based on the clustered index key 聚集索引基于聚集索引键按顺序排序和存储表或视图中的数据行。
The database engine does not consider nonkey columns when calculating the number of index key columns or index key size 数据库引擎计算索引键列数或索引键大小时，不考虑非键列。
Columns that have existing data in the row overflow data allocation unit . if a clustered index is created on a 聚集索引的索引键不能包含在row _ overflow _ data分配单元中具有现有数据的
