SQL & PL/SQL

dear all

my following concatenation code works fine in a dynamic function as i return value in a single variable:

query_str := 'SELECT STOCK'
|| '||'
|| ' DMS FROM '
|| ' ARTICLE'
|| ' WHERE ART_NO = :ARTNO';

-- Stock and DMS are two different fields.

but i need a static Sring between two fields it give error, i try following:

query_str := 'SELECT STOCK'
|| '||'
|| 'Dms is '
|| '||'
|| ' DMS FROM '
|| ' ARTICLE'
|| ' WHERE ART_NO = :ARTNO';

It gives error 'Unknown Dms is'

Kindly guide me

Regards

Sayeed