1 files changed, 31 insertions, 24 deletions

diff --git a/sqlglot/optimizer/simplify.py b/sqlglot/optimizer/simplify.py
index 6ae08d0..f53023c 100644
--- a/sqlglot/optimizer/simplify.py
+++ b/sqlglot/optimizer/simplify.py
@@ -49,32 +49,32 @@ def simplify(
 
     dialect = Dialect.get_or_raise(dialect)
 
-    # group by expressions cannot be simplified, for example
-    # select x + 1 + 1 FROM y GROUP BY x + 1 + 1
-    # the projection must exactly match the group by key
-    for group in expression.find_all(exp.Group):
-        select = group.parent
-        assert select
-        groups = set(group.expressions)
-        group.meta[FINAL] = True
-
-        for e in select.expressions:
-            for node, *_ in e.walk():
-                if node in groups:
-                    e.meta[FINAL] = True
-                    break
-
-        having = select.args.get("having")
-        if having:
-            for node, *_ in having.walk():
-                if node in groups:
-                    having.meta[FINAL] = True
-                    break
-
     def _simplify(expression, root=True):
         if expression.meta.get(FINAL):
             return expression
 
+        # group by expressions cannot be simplified, for example
+        # select x + 1 + 1 FROM y GROUP BY x + 1 + 1
+        # the projection must exactly match the group by key
+        group = expression.args.get("group")
+
+        if group and hasattr(expression, "selects"):
+            groups = set(group.expressions)
+            group.meta[FINAL] = True
+
+            for e in expression.selects:
+                for node, *_ in e.walk():
+                    if node in groups:
+                        e.meta[FINAL] = True
+                        break
+
+            having = expression.args.get("having")
+            if having:
+                for node, *_ in having.walk():
+                    if node in groups:
+                        having.meta[FINAL] = True
+                        break
+
         # Pre-order transformations
         node = expression
         node = rewrite_between(node)
@@ -266,6 +266,8 @@ INVERSE_COMPARISONS: t.Dict[t.Type[exp.Expression], t.Type[exp.Expression]] = {
     exp.GTE: exp.LTE,
 }
 
+NONDETERMINISTIC = (exp.Rand, exp.Randn)
+
 
 def _simplify_comparison(expression, left, right, or_=False):
     if isinstance(left, COMPARISONS) and isinstance(right, COMPARISONS):
@@ -276,7 +278,7 @@ def _simplify_comparison(expression, left, right, or_=False):
         rargs = {rl, rr}
 
         matching = largs & rargs
-        columns = {m for m in matching if isinstance(m, exp.Column)}
+        columns = {m for m in matching if not _is_constant(m) and not m.find(*NONDETERMINISTIC)}
 
         if matching and columns:
             try:
@@ -292,7 +294,12 @@ def _simplify_comparison(expression, left, right, or_=False):
                 l = l.name
                 r = r.name
             else:
-                return None
+                l = extract_date(l)
+                if not l:
+                    return None
+                r = extract_date(r)
+                if not r:
+                    return None
 
             for (a, av), (b, bv) in itertools.permutations(((left, l), (right, r))):
                 if isinstance(a, LT_LTE) and isinstance(b, LT_LTE):