How do I join two tables based on timestamps that don't exactly match?

Question

Hi everyone!

I am having an issue where I have Data Table 1 as shown below with a timestamp column and various columns of data

TimestampColumn AColumn B02/08/2021 11:45 AMA1B102/08/2021 1:39 PMA2B202/08/2021 11:37 PMA3B302/13/2021 12:01 AMA4B402/13/2021 4:00 PMA5B502/13/2021 10:22 PMA6B602/18/2021 9:00 AMA7B702/18/2021 12:01 PMA8B802/21/2021 9:15 AMA9B902/21/2021 11:50 AMA10B1002/21/2021 3:00 PMA11B11

And Data Table 2 also with a timestamp column and corresponding columns of data

TimestampColumn CColumn D02/08/2021 11:24 AMC1D102/13/2021 12:07 AMC2D202/18/2021 10:29 AMC3D302/21/2021 11:16 AMC4D4

I would like to join these two data tables together where I preserve the timestamp column of Data Table 1, but join Columns C and D from Data Table 2 into Data Table 1 where the data is applied starting from the time indicated in the timestamp in Data Table 2.  The resulting column would look like this:

TimestampColumn AColumn BColumn CColumn D02/08/2021 11:45 AMA1B1C1D102/08/2021 1:39 PMA2B2C1D102/08/2021 11:37 PMA3B3C1D102/13/2021 12:01 AMA4B4C1D102/13/2021 4:00 PMA5B5C2D202/13/2021 10:22 PMA6B6C2D202/18/2021 9:00 AMA7B7C2D202/18/2021 12:01 PMA8B8C3D302/21/2021 9:15 AMA9B9C3D302/21/2021 11:50 AMA10B10C4D402/21/2021 3:00 PMA11B11C4D4

Thanks in advance for any help!

Dan_Obermiller · Answer

Of course you are right @txnelson. I just looked too quickly. I have edited my original reply.

txnelson · Answer

@Dan_Obermiller

2 of the rows do not match based upon date.  The table matching as shown seems to be based upon prior date closest to target date.

Dan_Obermiller · Answer

In your small example it looks like you are just matching based on date, not time. Could that possibly work instead?

EDIT: You can safely ignore this comment. I had looked too quickly at the example.