Report Builder filtering table based off another table parameters

Hi,Spikenaylor . I am glad to help you.
If you use the Filters function to filter the dataset, the system selects the parameter with a (0) suffix by default.

If this is the case for you, you need to remove “(0)” and make the whole parameter a list of values, so that the corresponding data can be filtered properly (I think there is an error in your parameter configuration settings)

this is my test data:

If you want to implement a similar join query (or more complex query logic for datasets, I'd prefer that you write the query statement artificially)
Using query statements + query parameters

Tutorial: Add parameters to your report (Report Builder) - SQL Server Reporting Services (SSRS) | Microsoft Learn

Like this:
Set up a separate parameter value dataset for the report parameters to get the corresponding parameter values.
 

The dataset DataSetMainTablePar used by the parameter [MonthCompleted]

SELECT
DISTINCT
MainTable.Completion_Month
FROM
  MainTable

This is then used in the final dataset to set the correct query parameters

I'm using a SQL Server datasource

You need to ensure that:

1. the parameters are set up with the correct type, whether they contain multiple values, (use “=” or “IN” in the query)
2. the parameter mapping is set correctly
3. Query parameters are used correctly in the query statement

This is my query code:

SELECT d.*
FROM DeliveryTable d
JOIN MainTable m ON d.Delivery_Month = m.Prep_Month
WHERE m.Completion_Month in ( @MonthCompleted );

I hope my suggestions give you good ideas, if you have any more questions, please clarify in a follow-up reply.
Best Regards,
Carson Jian,
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