将vba日期函数转换为sql

Question

I need help converting the following vba code to a similar SQL string.

    vDt = Now()
    vStartDate = UCase(Format(DateSerial(Year(vDt), Month(vDt) - 1, 1), "DD-MMM-YYYY"))
    vEndDate = UCase(Format(DateSerial(Year(vDt), Month(vDt), 0), "DD-MMM-YYYY"))

Answer 1

If I'm understanding this correctly, you want the start date to be the first day of the previous month and the end date to be the last day of the current month. Then you want to convert them to the date format DD-MMM-YYYY. If so, below would be the corresponding SQL:

DECLARE @now DATETIME;
DECLARE @start DATETIME;
DECLARE @end DATETIME;
SET @now = GETDATE();
SET @start = DATEADD(MONTH, -1, DATEADD(MONTH, DATEDIFF(MONTH, 0, @now), 0));
SET @end = EOMONTH(@now);

SELECT UPPER(REPLACE(CONVERT(VARCHAR(12), @start, 106), ' ', '-')) AS StartDate,
    UPPER(REPLACE(CONVERT(VARCHAR(12), @end, 106), ' ', '-')) AS EndDate;

EDIT - Sorry I should mention that this is in Microsoft T-SQL and not Teradata SQL Assistant (thank you @a_horse_with_no_name). I'm not familiar with Teradata so I can't give you the exact answer, however I believe you can find similar functions to translate the above answer.

Answer 2

In Teradata SQL you get the 1st day of the previous month using

 Trunc(Add_Months(Current_Date, -1), 'mon')

and the last day of the current month:

Last_Day(Current_Date)

Of course this returns a data, if you want a DD-MMM-YYYY string:

SELECT
   To_Char(Trunc(Add_Months(Current_Date, -1), 'MON'), 'DD-MON-YYYY')
  ,To_Char(Last_Day(Current_Date), 'DD-MON-YYYY')