- Fixed bug with :meth:`.Insert.from_select` method where the order

of the given names would not be taken into account when generating
the INSERT statement, thus producing a mismatch versus the column
names in the given SELECT statement.  Also noted that
:meth:`.Insert.from_select` implies that Python-side insert defaults
cannot be used, since the statement has no VALUES clause. [ticket:2895]

2 files changed, 20 insertions, 5 deletions

diff --git a/lib/sqlalchemy/sql/compiler.py b/lib/sqlalchemy/sql/compiler.py
index 1d38c9ad3..bd886bd40 100644
--- a/lib/sqlalchemy/sql/compiler.py
+++ b/lib/sqlalchemy/sql/compiler.py
@@ -1965,10 +1965,17 @@ class SQLCompiler(Compiled):
                     elif c.server_onupdate is not None:
                         self.postfetch.append(c)
 
-        # iterating through columns at the top to maintain ordering.
-        # otherwise we might iterate through individual sets of
-        # "defaults", "primary key cols", etc.
-        for c in stmt.table.columns:
+        if self.isinsert and stmt.select_names:
+            # for an insert from select, we can only use names that
+            # are given, so only select for those names.
+            cols = (stmt.table.c[elements._column_as_key(name)]
+                        for name in stmt.select_names)
+        else:
+            # iterate through all table columns to maintain
+            # ordering, even for those cols that aren't included
+            cols = stmt.table.columns
+
+        for c in cols:
             if c.key in parameters and c.key not in check_columns:
                 value = parameters.pop(c.key)
                 if elements._is_literal(value):
diff --git a/lib/sqlalchemy/sql/dml.py b/lib/sqlalchemy/sql/dml.py
index 3501417a4..83f4365d7 100644
--- a/lib/sqlalchemy/sql/dml.py
+++ b/lib/sqlalchemy/sql/dml.py
@@ -426,7 +426,7 @@ class Insert(ValuesBase):
         """
         ValuesBase.__init__(self, table, values, prefixes)
         self._bind = bind
-        self.select = None
+        self.select = self.select_names = None
         self.inline = inline
         self._returning = returning
         self.kwargs = kwargs
@@ -470,6 +470,13 @@ class Insert(ValuesBase):
              sel = select([table1.c.a, table1.c.b]).where(table1.c.c > 5)
              ins = table2.insert(inline=True).from_select(['a', 'b'], sel)
 
+        .. note::
+
+           A SELECT..INSERT construct in SQL has no VALUES clause.  Therefore
+           :class:`.Column` objects which utilize Python-side defaults
+           (e.g. as described at :ref:`metadata_defaults_toplevel`)
+           will **not** take effect when using :meth:`.Insert.from_select`.
+
         .. versionadded:: 0.8.3
 
         """
@@ -480,6 +487,7 @@ class Insert(ValuesBase):
         self.parameters, self._has_multi_parameters = \
                 self._process_colparams(dict((n, Null()) for n in names))
 
+        self.select_names = names
         self.select = _interpret_as_select(select)
 
     def _copy_internals(self, clone=_clone, **kw):