Parameters within a sql statement

In Cache ObjectScript p_Branch isn't a valid identifier, because the underscore character is used as the concatenation operator.

Does your attempt work if you change p_Branch to pBranch ?

If not, please show us your SQL in its complete context.

Is your class located within the User package? Ex: User.Location?
If you REALLY want to use _ then at least wrap the alias inside double quotes.
 

Can you provide more details on what exactly you're trying to accomplish? As you said, the last query works. What exactly is missing? Are you trying to get a prompt (outside of Cache I'm guessing) with the parameter name?

Here is the procedure sample:
http://docs.intersystems.com/latest/csp/docbook/DocBook.UI.Page.cls?KEY…

ClassMethod CalcAvgScore(firstname As %String,lastname As %String) [sqlproc]
{
  New SQLCODE,%ROWID
  &sql(UPDATE students SET avgscore = 
    (SELECT AVG(sc.score) 
     FROM scores sc, students st
     WHERE sc.student_id=st.student_id 
       AND st.lastname=:lastname
       AND st.firstname=:firstname)
     WHERE students.lastname=:lastname
       AND students.firstname=:firstname)

  IF ($GET(%sqlcontext)'= "") {
    SET %sqlcontext.%SQLCODE = SQLCODE
    SET %sqlcontext.%ROWCOUNT = %ROWCOUNT
  }
  QUIT
}

Instead of using SQL to define PROCEDURES, even though you can, it's easier to create one using your own class. Just declare it as [ SqlProc] and it'll be available to use inside SQL. You can use that way to define a SQL function as well.