Cache and Raid performance. One of the key limitations of spinning disk hardware is the use of a physical reading armature and the time this takes to move across the surface of a diskâs platter to the required data blocks.
Constraints are part of a database schema definition. A constraint is usually associated with a table and is created with a CREATE CONSTRAINT or CREATE ASSERTION SQL statement. They define certain properties that data in a database must comply with.
A. Create a PRIMARY KEY constraint on a column. The following example shows the column definition for a PRIMARY KEY constraint with a clustered index on the EmployeeID column of the Employee table. Because a constraint name is not specified, the system supplies the constraint name.