减去1个月更新表SQL Server

Question

我需要将所有issuedat（日期字段）从列paidat（日期字段）更新为不到一个月

前：

if paidat = 01/02/2011 then issuedat should = 01/01/2011

UPDATE invoices SET invoices.issuedat = ????

Answer 1

UPDATE invoices SET invoices.issuedat = dateadd(MM,-1,paidat)