- Fixed two issues regarding Sybase reflection, allowing tables

without primary keys to be reflected as well as ensured that
a SQL statement involved in foreign key detection is pre-fetched up
front to avoid driver issues upon nested queries.  Fixes here
courtesy Eugene Zapolsky; note that we cannot currently test
Sybase to locally verify these changes.
fixes #3508  fixes #3509

1 files changed, 9 insertions, 6 deletions

diff --git a/lib/sqlalchemy/dialects/sybase/base.py b/lib/sqlalchemy/dialects/sybase/base.py
index ae0473a3e..b3f8e307a 100644
--- a/lib/sqlalchemy/dialects/sybase/base.py
+++ b/lib/sqlalchemy/dialects/sybase/base.py
@@ -608,8 +608,8 @@ class SybaseDialect(default.DefaultDialect):
           FROM sysreferences r JOIN sysobjects o on r.tableid = o.id
           WHERE r.tableid = :table_id
         """)
-        referential_constraints = connection.execute(REFCONSTRAINT_SQL,
-                                                     table_id=table_id)
+        referential_constraints = connection.execute(
+            REFCONSTRAINT_SQL, table_id=table_id).fetchall()
 
         REFTABLE_SQL = text("""
           SELECT o.name AS name, u.name AS 'schema'
@@ -740,10 +740,13 @@ class SybaseDialect(default.DefaultDialect):
         results.close()
 
         constrained_columns = []
-        for i in range(1, pks["count"] + 1):
-            constrained_columns.append(pks["pk_%i" % (i,)])
-        return {"constrained_columns": constrained_columns,
-                "name": pks["name"]}
+        if pks:
+            for i in range(1, pks["count"] + 1):
+                constrained_columns.append(pks["pk_%i" % (i,)])
+            return {"constrained_columns": constrained_columns,
+                    "name": pks["name"]}
+        else:
+            return {"constrained_columns": [], "name": None}
 
     @reflection.cache
     def get_schema_names(self, connection, **kw):