i have to convert the following columns from decimal to datetime. please advice a clear syntax
[ExpDate] [decimal](18, 0) NULL yymmdd to ExpirationDate datetime(6)
[DateLastPlastic] [decimal](18, 0) NULL, ymmdd to PrevPlasticDate datetime(6)
[DateLastPinMailer] [decimal](18, 0) NULL, ymmdd to PrevPinMailerDate datetime(6)