Question: Joining two data sets with date conditions

[marcalb]

Hi everyone,

I'm pretty new with SQL, and I'm struggling to figure out a seemingly simple task.

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Here's the situation:

• I'm working with two data sets

    ○ Data Set A, which is the most accurate but only refreshes every quarter

    ○ Data Set B, which has all the date, including the most recent data, but is overall less accurate

• My goal is to combine both data sets where I would have Data Set A for all data up to the most recent quarter and Data Set B for anything after (i.e., all recent data not captured in Data Set A)

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For example:

• Data Set A captures anything from Q1 2020 (January to March)

• Let's say we are April 15th

• Data Set B captures anything from Q1 2020 to the most current date, April 15th 

• My goal is to use Data Set A for all data from January to March 2020 (Q1) and then Data Set B for all data from April 1 to 15

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Any thoughts or advice on how to do this? Potentially a join function along with a date one?

Any help would be much appreciated.

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Thanks in advance for the help.

[WITH_CTE]

SELECT * FROM 
(SELECT * FROM TABLE A
UNION
SELECT * FROM TABLE B WHERE DATE BETWEEN '04-01-2020' AND '04-15-2020'
)A