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.
SQL DEFAULT Constraint on CREATE TABLE. The following SQL creates a DEFAULT constraint on the City column when the Persons table is created:My SQL / SQL Server / Oracle / MS Access:he following SQL creates a DEFAULT constraint on the City column when the Persons table is created: My SQL / SQL Server / Oracle / MS Access: