How to create a new content database for a web application

New-SPContentDatabase

The New-SPContentDatabase cmdlet creates a new content database and attaches it to the specified Web application.

New-SPContentDatabase [-Name] <String> [-WebApplication] <SPWebApplicationPipeBind> [-AssignmentCollection <SPAssignmentCollection>] [-AssignNewDatabaseId <SwitchParameter>] [-ChangeSyncKnowledge <SwitchParameter>] [-ClearChangeLog <SwitchParameter>] [-Confirm [<SwitchParameter>]] [-DatabaseCredentials <PSCredential>] [-DatabaseServer <String>] [-MaxSiteCount <Int32>] [-WarningSiteCount <Int32>] [-WhatIf [<SwitchParameter>]]

Example

New-SPContentDatabase "MyDatabase" -DatabaseServer "MyServer" -WebApplication http://sitename

Additional details