SQL queries data in recent years and months

Select   Dateadd ( Month , -  3 , Getdate ()) --  Return a time. query the desired data based on the time point.  --  Detailed description of the dateadd function:  --  Dateadd (interval, number, date)  --  Interval is required. String expression, indicating the time interval to be added.  -- Yyyy  --  Q quarter  --  M month  --  Y number of days in a year  --  D  --  Number of days per week  --  WW week  --  H hour  --  N minutes  -- S seconds  --  Number is required. It is a numerical expression.  --  The number of time intervals to be added. A numeric expression can be a positive number (to get the future date) or a negative number (to get the past date ).  --  Date is required. The comparison time during query. getdate () indicates the current time in SQL.  --  Example:  Select   Dateadd ( Month , -  3 , Getdate ()) --  Returns a time point three months ago based on the current time.  Select   Dateadd (Yyyy, -  3 , Getdate ()) --  Returns a time point three years ago based on the current time.  Select   Dateadd ( Month , 3 , Getdate ())--  Based on the current time, a time point after three months is returned.