Use . instead of __ to separate the qualified bound variables created…

… by unbind

The double underscore is already used by the native postgres adapter
to specify types.

There was already a partial fix for this earlier in the SQLite
adapter, but it only handled the SQL serialization.  This completes
that fix by also handling the bind variables.

lib/sequel/adapters/sqlite.rb

@@ -217,7 +217,7 @@ module ArgumentMapper
         # but with the keys converted to strings.
         def map_to_prepared_args(hash)
           args = {}
-          hash.each{|k,v| args[k.to_s] = v}
+          hash.each{|k,v| args[k.to_s.gsub('.', '__')] = v}
           args
         end
 

lib/sequel/ast_transformer.rb

@@ -116,7 +116,18 @@ def v(o)
   # and use the bound variables to execute it with the same values.
   #
   # This class only does a limited form of unbinding where the variable names
-  # and values can be associated unambiguously.
+  # and values can be associated unambiguously.  The only cases it handles
+  # are <tt>SQL::ComplexExpression<tt> with an operator in +UNBIND_OPS+, a
+  # first argument that's an instance of a member of +UNBIND_KEY_CLASSES+, and
+  # a second argument that's an instance of a member of +UNBIND_VALUE_CLASSES+.
+  #
+  # So it can handle cases like:
+  #
+  #   DB.filter(:a=>1).exclude(:b=>2).where{c > 3}
+  #
+  # But it cannot handle cases like:
+  #
+  #   DB.filter(:a + 1 < 0)
   class Unbinder < ASTTransformer
     # The <tt>SQL::ComplexExpression<tt> operates that will be considered
     # for transformation.
@@ -149,7 +160,7 @@ def bind_key(obj)
       when SQL::Identifier
         bind_key(obj.value)
       when SQL::QualifiedIdentifier
-        :"#{bind_key(obj.table)}__#{bind_key(obj.column)}"
+        :"#{bind_key(obj.table)}.#{bind_key(obj.column)}"
       else
         raise Error, "unhandled object in Sequel::Unbinder#bind_key: #{obj}"
       end

spec/core/dataset_spec.rb

@@ -3657,7 +3657,7 @@ def @ds.fetch_rows(sql, &block)
   end
 
   specify "should handle QualifiedIdentifiers" do
-    @u[@ds.filter{foo__bar > 1}].should == ["SELECT * FROM t WHERE (foo.bar > $foo.bar)", {:foo__bar=>1}]
+    @u[@ds.filter{foo__bar > 1}].should == ["SELECT * FROM t WHERE (foo.bar > $foo.bar)", {:"foo.bar"=>1}]
   end
 
   specify "should handle deep nesting" do