Database concepts

• In a multi user environment there are 2 models for updating data in a database. They are, 
• optimistic concurrency
• pessimistic concurrency
• Types of joins in SQL
• See Stackoverflow article
• Table naming conventions
• http://stackoverflow.com/questions/338156/table-naming-dilemma-singular-vs-plural-names

Following are scenarios for Availability

Log Shipping
Automatically send transaction log backups from primary database on the primary server to secondary database on a secondary server. Good for disaster recovery.

Replication
Almost same as log shipping.

Mirroring
failover technique

Failover clustering
advanced database mirroring

MSDN - Log shipping


Resources

http://msdn.microsoft.com/en-us/library/bb404102.aspx
http://msdn.microsoft.com/en-us/library/aa0416cz(v=vs.110).aspx
http://stackoverflow.com/questions/659489/pessimistic-versus-optimistic-concurrency-locking-versus-feedback
http://stackoverflow.com/questions/13432489/concurrent-updates-handling-in-asp-net-or-sql-server-2008