What Is Integrity?

Several points about data integrity:

• Assures database data and structures reflects all changes made to them in the correct sequence.
• Locks ensure data integrity and maximum concurrent access to data. Commit statement releases all locks. Types of locks are given below.
• Data Locks protects data i.e. Table or Row lock.
• Dictionary Locks protects the structure of database object i.e. ensures table's structure does not change for the duration of the transaction.
• Internal Locks and Latches protects the internal database structures. They are automatic.
• Exclusive Lock allows queries on locked table but no other activity is allowed.
• Share Lock allows concurrent queries but prohibits updates to the locked tables.
• Row Share allows concurrent access to the locked table but prohibits for a exclusive table lock.
• Row Exclusive same as Row Share but prohibits locking in shared mode.
• Shared Row Exclusive locks the whole table and allows users to look at rows in the table but prohibit others from locking the table in share or updating them.
• Share Update are synonymous with Row Share.