SharePoint and SQL Server both goes together – hands to hand. SharePoint installation is very interesting. At various organizations, the installation is very different and have various needs. SQL Server installation with SharePoint is equally important and I have often seen that it is being neglected.
Microsoft has published the Deployment Guide for SharePoint Foundation. It talks about various database aspects as well.
For optimal sharepoint installation the required version of SQL Server, including service packs and cumulative updates must be installed on the database server. The installation must include any additional features, such as SQL Analysis Services, and the appropriate SharePoint Foundation logins have to be added and configured. The database server must be hardened and, if it is required, databases must be created by the DBA.
Reference: Pinal Dave (http://blog.SQLAuthority.com)