Recently has some trouble getting SQL configured for a RC2 lab, a few of the requirements have been updated. Below are the various requirements for correctly installing SQL for ConfigMgr 2012 RC2.
Make sure to review the supported configurations on the TechNet site.
SQL Server Versions
SQL Server 2008 SP2 with CU7 (Standard or Enterprise)
SQL Server 2008 R2 with SP1 and CU4 (Standard or Enterprise)
SQL Server Express 2008 R2 with SP1 and CU4 (Secondary Sites)
NOTE: If you use SQL Server Standard, your CAS will only support 50k clients
ConfigMgr 2012 requires SQL_Latin1_General_CP1_CI_AS collation.
SQL Server Features
Only Database Engine Services is required. SQL Server replication is not needed.