From cf8e5e3cf5b0e1be05a611c8828690acfcd2b9fa Mon Sep 17 00:00:00 2001
From: donkopotamus <derek.harland@finq.co.nz>
Date: Fri, 17 Jan 2014 11:00:24 +1300
Subject: [PATCH] Bug Fix: Stop generating bad sql if an empty
 UniqueConstraint() is given

---
 lib/sqlalchemy/dialects/mssql/base.py |  2 ++
 lib/sqlalchemy/sql/compiler.py        |  2 ++
 test/sql/test_constraints.py          | 22 ++++++++++++++++++++++
 3 files changed, 26 insertions(+)

diff --git a/lib/sqlalchemy/dialects/mssql/base.py b/lib/sqlalchemy/dialects/mssql/base.py
index c024b62304..6c942b270a 100644
--- a/lib/sqlalchemy/dialects/mssql/base.py
+++ b/lib/sqlalchemy/dialects/mssql/base.py
@@ -1069,6 +1069,8 @@ class MSDDLCompiler(compiler.DDLCompiler):
         return text
 
     def visit_unique_constraint(self, constraint):
+        if len(constraint) == 0:
+            return ''
         text = ""
         if constraint.name is not None:
             text += "CONSTRAINT %s " % \
diff --git a/lib/sqlalchemy/sql/compiler.py b/lib/sqlalchemy/sql/compiler.py
index ade3c623af..5c5bfad551 100644
--- a/lib/sqlalchemy/sql/compiler.py
+++ b/lib/sqlalchemy/sql/compiler.py
@@ -2511,6 +2511,8 @@ class DDLCompiler(Compiled):
         return preparer.format_table(table)
 
     def visit_unique_constraint(self, constraint):
+        if len(constraint) == 0:
+            return ''
         text = ""
         if constraint.name is not None:
             text += "CONSTRAINT %s " % \
diff --git a/test/sql/test_constraints.py b/test/sql/test_constraints.py
index 393bcd4480..cb4b73ec8b 100644
--- a/test/sql/test_constraints.py
+++ b/test/sql/test_constraints.py
@@ -544,6 +544,28 @@ class ConstraintCompilationTest(fixtures.TestBase, AssertsCompiledSQL):
                 "FOREIGN KEY(foo_bar) REFERENCES foo (bar))"
         )
 
+    def test_empty_pkc(self):
+        # test that an empty primary key is ignored
+        metadata = MetaData()
+        tbl = Table('test', metadata,
+                    Column('x', Integer, autoincrement=False),
+                    Column('y', Integer, autoincrement=False),
+                    PrimaryKeyConstraint())
+        self.assert_compile(schema.CreateTable(tbl),
+                            "CREATE TABLE test (x INTEGER, y INTEGER)"
+                            )
+
+    def test_empty_uc(self):
+        # test that an empty constraint is ignored
+        metadata = MetaData()
+        tbl = Table('test', metadata,
+                    Column('x', Integer, autoincrement=False),
+                    Column('y', Integer, autoincrement=False),
+                    UniqueConstraint())
+        self.assert_compile(schema.CreateTable(tbl),
+                            "CREATE TABLE test (x INTEGER, y INTEGER)"
+                            )
+
     def test_deferrable_column_check(self):
         t = Table('tbl', MetaData(),
                   Column('a', Integer),
-- 
2.47.3