question related to using join in Expression Rule

Hi All,

i have a query related to using join in expression 

as you can see their is a logic mentioned in below code which is i am using in a database view but now i need to use this logic in expression rule to fetch the data so any one can help me to implement this logic or you can give any example

we requird the filter on below case

SELECT
a.IDeChangeAffectedElements as IDsiteHistory,
a.eChangeRequestDetailsID,
a.siteid,
a.sitename,
a.location,
a.network,
a.elmid,
a.elmalias,
a.elmaddress,
a.createdby,
a.createddate,
a.modifiedby,
a.modifieddate ,
b.plannedstartdate as startdate,
b.plannedenddate as enddate,
b.EtimeCode
FROM
eChangeAffectedElements a WITH(NOLOCK)
left join eChangeRequestDetails b WITH(NOLOCK)
on a.eChangeRequestDetailsID = b.IDeChangeRequestNumber

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  • 0
    Certified Lead Developer

    Expressions in Appian do not support DB joins. I suggest to have a look at synced records and related record queries.

  • 0
    Certified Lead Developer

    If you're doing traditional (entity-wise) querying in the expression rule, you merely create a DB view that utilizes the joining logic you want, create a Data Store Entity pointing to that view, then query it in your code.

    If you're using RecordType data (synced records etc), you should be able to do basically the same thing inherently in your data structure by configuring Related Record Data.

    As Stefan mentioned, "joins" in expression code aren't really a thing.  The closest you could come is to query from table A and query from table B with filtering on the values you've already retrieved from A, which could work depending on what your requirements are, but doesn't scale well (it gets pretty costly if your volume of queried data starts to become large at all), and doing the necessary coding requires precise and sometimes confusing intricacy.

  • 0
    Certified Senior Developer

    hi   there are two ways, One could be creating a view for that code and next creating a data store entity in Appian and querying the DSE. The approach would be to create a stored procedure in the database for this code, and in Appian call the stored procedure using the function named a!executeStoredProcedureForQuery()