Referencing row values in pyodbc when column name contains dashes (hyphens)

Question

I am new to python and pyodbc

I try to print the first a row from a table from a progress openedge database. (Windows 7) Here is the code block that is not running:

cursor.execute("select my-nr, my-dt-my from mytable")
row = cursor.fetchone()
print(row.my-nr, row.my-dt-my)

This gives errors undefined name: 'nr' undefined name 'dt' undefined name 'my'

I guess it has something to do with the minus - symbols behind the dot . in print(row.my-nr, row.my-dt-my)

It was easy to print out the table names and column names from the database earlier but for some reason printing out rows is harder.

Any ideas how to get the rows printed?

Answer 1

pyodbc allows us to reference values in a pyodbc.Row object using the form row.column_name provided that the column names are legal Python identifiers. So, for example, we can do something like

row = crsr.fetchone()
print(row.city)

to print the value of the "city" column. Unfortunately, my-nr is not a legal Python identifier so if we try to print the value of the "my-nr" column using ...

row = crsr.fetchone()
print(row.my-nr)  # error

... Python parses that as "row.my minus nr" where row.my would be interpreted as a column in the Row object and nr would be interpreted as a Python variable.

To work around the issue we can grab a list of the column names, merge those names with the row values into a dictionary, and then refer to the values in the dictionary:

crsr.execute(sql)
col_names = [x[0] for x in crsr.description]

row = crsr.fetchone()
row_as_dict = dict(zip(col_names, row))
print(row_as_dict['my-nr'])  # no error

Answer 2

The most simple solution I can think of is this. First, columns containing hyphens need to be quoted in OpenEdge (see here). Second, you can alias the columns so they can be referenced as valid Python attributes. You'll need to do something like this:

cursor.execute('select "my-nr" as mynr, "my-dt-my" as mydtmy from mytable')
row = cursor.fetchone()
print(row.mynr, row.mydtmy)

Good luck!