abp/templates/service/host/IdentityServerHost/appsettings.json

{
  "ConnectionStrings": {
    "Default": "Server=localhost;Database=MyProjectName_Identity;Trusted_Connection=True;MultipleActiveResultSets=true",

    "SqlServerCache": "Server=localhost;Database=MyProjectName_Cache;Trusted_Connection=True;MultipleActiveResultSets=true"
  }
}