column order in SELECT * statement - guaranteed?

Question

I am using an ORM (sqlalchemy) to fetch data from a PG database. I want to avoid specifying all the table column names in my hand crafted SQL statements*.

My assumpt

Answer 1

Let's consider the SQL standard, section 7.9 as specified here:

http://www.contrib.andrew.cmu.edu/~shadow/sql/sql1992.txt

 ::=
          SELECT [  ]  
[...]
 ::=
            
          |  [ {   }... ]

[...]
Syntax Rules
1) Let T be the result of the .
3) Case:
       a) [...]
       b) Otherwise, the  "*" is equivalent to a  sequence in which each  is a
           that references a column of T and each
          column of T is referenced exactly once. The columns are ref-
          erenced in the ascending sequence of their ordinal position
          within T.


So, in other words, yes, the SQL standard specifies that columns are to be projected according to their ordinal position within T. Note, that things get a bit tricky, when your  consists of several tables involving JOIN .. USING or NATURAL JOIN clauses. However, when selecting from a simple table, you're probably fine assuming that the order is as expected.
For completeness, the meaning of an ordinal position within T for tables is explained further down in 11.4 :
General Rules
     5) [...] The ordinal position included
        in the column descriptor is equal to the degree of T. [...]
And then in 11.11   (for ALTER TABLE statements)
General Rules
     4) [...] In particular, the degree of T
        is increased by 1 and the ordinal position of that column is
        equal to the new degree of T as specified in the General Rules
        of Subclause 11.4, "".
There are quite a few other SQL statements and clauses that depend on the formal specification of ordinal positions within 
. Some examples:
13.8  
     (when omitting the ``)
20.2 
     (when `` contains an ``)
Postgres, in particular, is quite standards-compliant, so if you really want to SELECT *, go ahead!

                                                        

              
                
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