Passing multivalue parameters in an external url ssrs

In most of the reports, we use multivalue parameters and for that we can directly write sql query in a separate data sets and modify the main dataset. It works fine for BIDS and Report Server for multi value parameters. But when we need to pass parameter values from the external portal to the reports then follow below steps:

1) Create a split function in your database (Many examples are available online)
2) Create a separate dataset for multivalue parameters
3) Change main dataset to populate multivalue parameter values from split function i.e: and (param1 in        
    (select column_value as param1 from table(HR.SPLIT(:Param1))) OR :param1 = ‘ALL’)
4) Go to the main dataset properties –> parameter –> select multivalue parameter expression –> add
    this: =Join(Parameters!Param1.Value,”,”)
5) It should work now

For the URL populate multivalue paramter value list externally using sql query. I have also included 'ALL' as a value in a list

Ex: select distinct param1 from table1
       where param1 is not null
       union
      select ‘ALL’ as param1 from dual

Thank you

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