Passing Parms to Query Manager

Question

I have seen several questions and answers in the forum on this but would like to confirm what I perceive to be the limitations.
The following code works and allows the entry of two parms:
set @parm_rep = (SELECT t0.slpcode FROM oinv t0 where t0.slpcode = '[%0]' )
set @parm_date = (SELECT t0.docduedate FROM oinv t0 where t0.docduedate = '[%1]' )
Requirement 1: table alias must be the same. That is, the above works but the following does not
set @parm_rep = (SELECT t0.slpcode FROM oinv t0 where t0.slpcode = '[%0]' )
set @parm_date = (SELECT t1.docduedate FROM oinv t1 where t1.docduedate = '[%1]' )
Requirement 2: tables must be the same. That is, the following does not work
set @parm_rep = (SELECT t1.slpcode FROM oslp t1 where t1.slpname = '[%0]' )
set @parm_date = (SELECT t1.docduedate FROM oinv t1 where t1.docduedate = '[%1]' )
Requirement 2, in particular, prevents me from allowing the User to select from a list of Salesrep names and Invoice dates because the Salesrep name is not carried on the Invoice, only the code.
In general, I can not have parameters set from different tables for use later in the query and am restricted to only paremeters that are represented within one specific table. I then created my own table which contained the combination of fields I wanted to select from. While I could select from that table in Query Manager, I was unable to set a parm from that table.

Answer 1

You can use more table for getting parameter values. And you donu2019t need to use only existing values from the tables. You can close the select inside a comment and use the manually entered parameter values.
Like this:
declare @n char(20)
declare @i char(20)
/*SELECT T0.[DocNum], T1.[ItemCode]
FROM ORDR T0  INNER JOIN RDR1 T1 ON T0.DocEntry = T1.DocEntry
WHERE T0.[DocNum] ='[%1]' and  T1.[ItemCode] ='[%0]'*/
set @n='[%1]'
set @i='[%0]'
select @n,@i