ANSI DATETIME上的无效操作（在Teradata中将一个时间戳减去另一个时间戳）

Question

I would like to create a WHERE condition to return results where only 1 day has passed between two timestamps. I tried this:

SELECT * FROM RDMAVWSANDBOX.VwNIMEventFct
INNER JOIN VwNIMUserDim ON VwNIMUserDim.NIM_USER_ID = VwNIMEventFct.NIM_USER_ID
INNER JOIN rdmatblsandbox.TmpNIMSalesForceDB ON TmpNIMSalesForceDB.EMAIL = VwNIMUserDim.USER_EMAIL_ADDRESS
WHERE (CONTRACT_EFFECTIVE_DATE - EVENT_TIMESTAMP) =1

But the result was an error message "Invalid Operation On An ANSI DATETIME value".

I guess that, looking at the code now, Teradata has no way of knowing whether the "1" in "= 1" is a day, hour or year.

How would I select data where only 1 day has passed between CONTRACT_EFFECTIVE_DATE and EVENT_TIMESTAMP?

Same again for 2 days, and 3 days etc?

Answer 1

If both columns are DATEs you can use =1 which means one day.

For Timestamps you need to tell what kind of interval you want:

WHERE (CONTRACT_EFFECTIVE_DATE - EVENT_TIMESTAMP) DAY = INTERVAL '1' DAY

But i'm not shure if this is what you really want, what's your definition of 1 day ?

Edit:

Based on your comment the best way should be:

WHERE CAST(CONTRACT_EFFECTIVE_DATE AS DATE) - CAST(EVENT_TIMESTAMP AS DATE) = 1

This avoids dealing with INTERVAL arithmetic :-)

Answer 2

Not sure about Teradata, but I think most versions of SQL have built-in date math functions. In MSSQL for instance you could do this:

...
WHERE DATEDIFF(DAY, CONTRACT_EFFECTIVE_DATE, EVENT_TIMESTAMP) = 1

Or if you wanted to make sure 24 hours had passed you could do:

...
WHERE DATEDIFF(HOUR, CONTRACT_EFFECTIVE_DATE, EVENT_TIMESTAMP) = 1

Other SQL's have their own versions of this, and you may have to use 'D' or 'DD' instead of 'DAY' or something (and maybe 'HH' instead of 'HOUR' likewise).