add postgres column type check

add specific method to handle named parameters

database/database_test.go

@@ -13,3 +13,13 @@ func TestEscapeTable(t *testing.T) {
 		t.Fatalf("TestEscapeTable: postgres check failed")
 	}
 }
+
+func TestGetNamedParameter(t *testing.T) {
+	if GetNamedParameter("mysql", "foo", 1) != "foo=?" {
+		t.Fatalf("TestGetNamedParameter: mysql check failed")
+	}
+
+	if GetNamedParameter("postgres", "foo", 1) != "foo=$1" {
+		t.Fatalf("TestGetNamedParameter: postgres check failed")
+	}
+}