Where those variable come from in datastage

Question

I have a User Variables Activity in datastage job like this.

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Name	Expression
START_DT	If START_DT = "" Then Ereplace(Oconv(@DATE-1, "D-YMD[4,2,2]","-","") ELSE START_DT
START_DT2	If START_DT = "" Then Ereplace(CurrentDateRT("")[1,4],"-","") ELSE START_DT
JOB_INVOCATION	DSJobName : "_" : if count(DSJobInvocationId, TYPE) <> 1 then TYPE else DSJobInvocationID

but I don't know what these expression mean.

like Where @Date is come frome? ( I guess that is the internal date when the program started.)

but I couldn't find CurrentDateRT is come from?

also, where those DSJobName, DSJOBInvocationId variable come from?

I coun't find that variable definition area...

Where can i find that area...??

and also How can I "Oconv(@DATE-1, "D-YMD[4,2,2]","-","") " expression to Oracle?

Answer 1

I don't know what these expression mean.

In general, these are programming components. You can reach them via the expression editor menu:

RTFM: https://www.ibm.com/docs/en/iis/11.7?topic=datastage-programming-components

like Where @Date is come frome?

That is a System Variable. As you already guessed, it comes from the system.

RTFM: https://www.ibm.com/docs/en/iis/11.7?topic=programming-system-variables

I couldn't find CurrentDateRT is come from?

According to its name ending on RT and the way it's used in the code, this seems to be a custom server routine. This routine in particular did not come with DataStage but has been programmed by someone who maintained your project. You should be able to find the object in the projects objects repository (the tree view, use the search in the designer).

RTFM: https://www.ibm.com/docs/en/iis/11.7?topic=datastage-working-routines

also, where those DSJobName, DSJOBInvocationId variable come from?

These are Job Status Macros. They can be used in all active stages and before/after subroutines.

RTFM = https://www.ibm.com/docs/en/iis/11.7?topic=interfaces-job-status-macros

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Have fun.