- added pyodbc for sybase driver.

- generalized the "freetds" / "unicode statements" behavior of MS-SQL/pyodbc
into the base Pyodbc connector, as this seems to apply to Sybase as well.
- generalized the python-sybase "use autocommit for DDL" into the pyodbc
connector.  With pyodbc, the "autocommit" flag on connection is used,
as Pyodbc seems to have more database conversation than python-sybase that
can't otherwise be suppressed.
- Some platforms will now interpret certain literal values
as non-bind parameters, rendered literally into the SQL
statement.   This to support strict SQL-92 rules that are
enforced by some platforms including MS-SQL and Sybase.
In this model, bind parameters aren't allowed in the
columns clause of a SELECT, nor are certain ambiguous
expressions like "?=?".  When this mode is enabled, the base
compiler will render the binds as inline literals, but only across
strings and numeric values.  Other types such as dates
will raise an error, unless the dialect subclass defines
a literal rendering function for those.  The bind parameter
must have an embedded literal value already or an error
is raised (i.e. won't work with straight bindparam('x')).
Dialects can also expand upon the areas where binds are not
accepted, such as within argument lists of functions
(which don't work on MS-SQL when native SQL binding is used).

1 files changed, 38 insertions, 6 deletions

diff --git a/lib/sqlalchemy/dialects/mssql/base.py b/lib/sqlalchemy/dialects/mssql/base.py
index 254aa54fd..4d697854f 100644
--- a/lib/sqlalchemy/dialects/mssql/base.py
+++ b/lib/sqlalchemy/dialects/mssql/base.py
@@ -843,8 +843,9 @@ class MSExecutionContext(default.DefaultExecutionContext):
 class MSSQLCompiler(compiler.SQLCompiler):
     returning_precedes_values = True
     
-    extract_map = compiler.SQLCompiler.extract_map.copy()
-    extract_map.update ({
+    extract_map = util.update_copy(
+        compiler.SQLCompiler.extract_map,
+        {
         'doy': 'dayofyear',
         'dow': 'weekday',
         'milliseconds': 'millisecond',
@@ -937,9 +938,9 @@ class MSSQLCompiler(compiler.SQLCompiler):
         kwargs['mssql_aliased'] = True
         return super(MSSQLCompiler, self).visit_alias(alias, **kwargs)
 
-    def visit_extract(self, extract):
+    def visit_extract(self, extract, **kw):
         field = self.extract_map.get(extract.field, extract.field)
-        return 'DATEPART("%s", %s)' % (field, self.process(extract.expr))
+        return 'DATEPART("%s", %s)' % (field, self.process(extract.expr, **kw))
 
     def visit_rollback_to_savepoint(self, savepoint_stmt):
         return "ROLLBACK TRANSACTION %s" % self.preparer.format_savepoint(savepoint_stmt)
@@ -1011,8 +1012,8 @@ class MSSQLCompiler(compiler.SQLCompiler):
         # "FOR UPDATE" is only allowed on "DECLARE CURSOR" which SQLAlchemy doesn't use
         return ''
 
-    def order_by_clause(self, select):
-        order_by = self.process(select._order_by_clause)
+    def order_by_clause(self, select, **kw):
+        order_by = self.process(select._order_by_clause, **kw)
 
         # MSSQL only allows ORDER BY in subqueries if there is a LIMIT
         if order_by and (not self.is_subquery() or select._limit):
@@ -1020,6 +1021,37 @@ class MSSQLCompiler(compiler.SQLCompiler):
         else:
             return ""
 
+class MSSQLStrictCompiler(MSSQLCompiler):
+    """A subclass of MSSQLCompiler which disables the usage of bind
+    parameters where not allowed natively by MS-SQL.
+    
+    A dialect may use this compiler on a platform where native
+    binds are used.
+    
+    """
+    ansi_bind_rules = True
+
+    def visit_in_op(self, binary, **kw):
+        kw['literal_binds'] = True
+        return "%s IN %s" % (
+                                self.process(binary.left, **kw), 
+                                self.process(binary.right, **kw)
+            )
+
+    def visit_notin_op(self, binary, **kw):
+        kw['literal_binds'] = True
+        return "%s NOT IN %s" % (
+                                self.process(binary.left, **kw), 
+                                self.process(binary.right, **kw)
+            )
+
+    def visit_function(self, func, **kw):
+        kw['literal_binds'] = True
+        return super(MSSQLStrictCompiler, self).visit_function(func, **kw)
+
+    #def render_literal_value(self, value):
+        # TODO! use mxODBC's literal quoting services here
+
 
 class MSDDLCompiler(compiler.DDLCompiler):
     def get_column_specification(self, column, **kwargs):