Merge "Support tuples of heterogeneous types for empty expanding IN"

2 files changed, 20 insertions, 7 deletions

diff --git a/lib/sqlalchemy/dialects/mysql/base.py b/lib/sqlalchemy/dialects/mysql/base.py
index cd17bcdc4..07eca78bb 100644
--- a/lib/sqlalchemy/dialects/mysql/base.py
+++ b/lib/sqlalchemy/dialects/mysql/base.py
@@ -1180,8 +1180,18 @@ class MySQLCompiler(compiler.SQLCompiler):
                                  fromhints=from_hints, **kw)
             for t in [from_table] + extra_froms)
 
-    def visit_empty_set_expr(self, type_):
-        return 'SELECT 1 FROM (SELECT 1) as _empty_set WHERE 1!=1'
+    def visit_empty_set_expr(self, element_types):
+        return (
+            "SELECT %(outer)s FROM (SELECT %(inner)s) "
+            "as _empty_set WHERE 1!=1" % {
+                "inner": ", ".join(
+                    "1 AS _in_%s" % idx
+                    for idx, type_ in enumerate(element_types)),
+                "outer": ", ".join(
+                    "_in_%s" % idx
+                    for idx, type_ in enumerate(element_types))
+            }
+        )
 
 
 class MySQLDDLCompiler(compiler.DDLCompiler):
diff --git a/lib/sqlalchemy/dialects/postgresql/base.py b/lib/sqlalchemy/dialects/postgresql/base.py
index 11fcc41d5..5251a000d 100644
--- a/lib/sqlalchemy/dialects/postgresql/base.py
+++ b/lib/sqlalchemy/dialects/postgresql/base.py
@@ -1485,14 +1485,17 @@ class PGCompiler(compiler.SQLCompiler):
                 if escape else ''
             )
 
-    def visit_empty_set_expr(self, type_, **kw):
+    def visit_empty_set_expr(self, element_types):
         # cast the empty set to the type we are comparing against.  if
         # we are comparing against the null type, pick an arbitrary
         # datatype for the empty set
-        if type_._isnull:
-            type_ = INTEGER()
-        return 'SELECT CAST(NULL AS %s) WHERE 1!=1' % \
-               self.dialect.type_compiler.process(type_, **kw)
+        return 'SELECT %s WHERE 1!=1' % (
+            ", ".join(
+                "CAST(NULL AS %s)" % self.dialect.type_compiler.process(
+                    INTEGER() if type_._isnull else type_,
+                ) for type_ in element_types or [INTEGER()]
+            ),
+        )
 
     def render_literal_value(self, value, type_):
         value = super(PGCompiler, self).render_literal_value(value, type_)