Teradata中不同月份的时间日期计算

Question

如何在Teradata中计算以下内容：

Beginning Of Previous Month, 
End Of Previous Month, 
Beginning Of Six Months Ago, 
Beginning Of Twelve Months Ago

感谢。

Answer 1

Beginning Of Previous Month:    add_months(current_date - (extract(day from current_date)-1), -1) 
End Of Previous Month:                     current_date - (extract(day from current_date))
Beginning Of Six Months Ago:    add_months(current_date - (extract(day from current_date)-1), -6) 
Beginning Of Twelve Months Ago: add_months(current_date - (extract(day from current_date)-1), -12) 

根据您的版本，可能会有一些功能：

td_month_begin(add_months(current_date,-1))
last_day(add_months(current_date,-1))

或者，如果这些列已存在，您可以检查（希望）现有的日历表。