Apply suggestions from code review

Co-authored-by: Raphael Guzman <38401847+guzman-raphael@users.noreply.github.com>

Author: jverswijver

CHANGELOG.md

@@ -5,7 +5,7 @@
 * Bugfix - Replace use of numpy aliases of built-in types with built-in type. (#938) PR #939
 * Bugfix - `ExternalTable.delete` should not remove row on error (#953) PR #956
 * Bugfix - Fix error handling of remove_object function in `s3.py` (#952) PR #955
-* Bugfix - Fix error when unioning multiple tables (#926) PR #964
+* Bugfix - Fix error when performing a union on multiple tables (#926) PR #964
 
 ### 0.13.2 -- May 7, 2021
 * Update `setuptools_certificate` dependency to new name `otumat`

datajoint/expression.py

@@ -625,15 +625,10 @@ def make_sql(self):
         if not arg1.heading.secondary_attributes and not arg2.heading.secondary_attributes:
             # no secondary attributes: use UNION DISTINCT
             fields = arg1.primary_key
-            if isinstance(arg1, Union):
-                sql1 = arg1.make_sql()
-            else:
-                sql1 = arg1.make_sql(fields)
-            if isinstance(arg2, Union):
-                sql2 = arg2.make_sql()
-            else:
-                sql2 = arg2.make_sql(fields)
-            return "({sql1}) UNION ({sql2})".format(sql1=sql1, sql2=sql2)
+            return "({sql1}) UNION ({sql2})".format(
+                sql1=arg1.make_sql() if isinstance(arg1, Union) else arg1.make_sql(fields),
+                sql2=arg2.make_sql() if isinstance(arg2, Union) else arg2.make_sql(fields),
+                )
         # with secondary attributes, use union of left join with antijoin
         fields = self.heading.names
         sql1 = arg1.join(arg2, left=True).make_sql(fields)

docs-parts/intro/Releases_lang1.rst

@@ -4,7 +4,7 @@
 * Bugfix - Replace use of numpy aliases of built-in types with built-in type. (#938) PR #939
 * Bugfix - `ExternalTable.delete` should not remove row on error (#953) PR #956
 * Bugfix - Fix error handling of remove_object function in `s3.py` (#952) PR #955
-* Bugfix - Fix error when unioning multiple tables (#926) PR #964
+* Bugfix - Fix error when performing a union on multiple tables (#926) PR #964
 
 0.13.2 -- May 7, 2021
 ----------------------

tests/test_relational_operand.py

@@ -1,4 +1,3 @@
-from os import stat
 import random
 import string
 import pandas
@@ -512,6 +511,4 @@ def test_union_multiple():
         # https://github.com/datajoint/datajoint-python/issues/926
         q1 = IJ & dict(j=2)
         q2 = (IJ & dict(j=2, i=0)) + (IJ & dict(j=2, i=1)) + (IJ & dict(j=2, i=2))
-        x = set(zip(*q1.fetch('i', 'j')))
-        y = set(zip(*q2.fetch('i', 'j')))
-        assert_set_equal(x, y)
+        assert q1.fetch() == q2.fetch()