获取上个月的数据在 sql 服务器中不起作用

Question

I am trying to get the previous month data according to the datetime in the column dynamically for example I have data like this

Now I want the records previous than Opendt. The problem is that I am getting the record after Opendt but I am getting empty when I am getting the record before 1 month or 2 month of Opendt

this is the query i am writing

select * from dbo.mytable where Valdate between OpenDt and dateadd(Month,-1,OpenDt)

the problem is that here -1 and -2 returning empty but when i am adding positive values 1, 2 and 3 I am getting the records after the OpenDt but not the before Dt Records.

I need the previous one or two month records before OpenDt

Answer 1

What is the data type of your Date columns? Are they of any of the date and/or time types described here https://docs.microsoft.com/en-us/sql/t-sql/functions/date-and-time-data-types-and-functions-transact-sql?view=sql-server-ver15 ?

If not, you may have to change the type for your queries as described here https://docs.microsoft.com/en-us/sql/t-sql/functions/try-cast-transact-sql?view=sql-server-ver15 (not recommended) OR reload the data with the correct types OR create new columns with correct types and update them with date/time values of your date columns. And then use the new columns/correctly typed data in your queries.

Answer 2

You need to reverse the BETWEEN. The lower value must always be first.

SELECT * 
FROM dbo.mytable
WHERE Valdate BETWEEN dateadd(Month,-1,OpenDt) AND OpenDt