Avoid dropping version table for offline SQL base

alembic/runtime/migration.py

@@ -639,10 +639,6 @@ def run_migrations(self, **kw: Any) -> None:
                         run_args=kw,
                     )
 
-        if self.as_sql and not head_maintainer.heads:
-            assert self.connection is not None
-            self._version.drop(self.connection)
-
     def _in_connection_transaction(self) -> bool:
         try:
             meth = self.connection.in_transaction  # type:ignore[union-attr]

docs/build/unreleased/1822.rst

@@ -0,0 +1,8 @@
+.. change::
+    :tags: bug, commands
+    :tickets: 1822
+
+    Fixed SQL output for commands such as ``stamp base --sql`` and
+    ``downgrade ...:base --sql`` to no longer emit ``DROP TABLE`` for the
+    Alembic version table.  This now matches online mode, where Alembic
+    updates the version rows but does not drop the version table.

tests/test_command.py

@@ -988,7 +988,7 @@ def test_version_to_none(self):
             command.downgrade(self.cfg, "%s:base" % self.c, sql=True)
         assert "CREATE TABLE alembic_version" not in buf.getvalue()
         assert "INSERT INTO alembic_version" not in buf.getvalue()
-        assert "DROP TABLE alembic_version" in buf.getvalue()
+        assert "DROP TABLE alembic_version" not in buf.getvalue()
         assert "DROP STEP 3" in buf.getvalue()
         assert "DROP STEP 2" in buf.getvalue()
         assert "DROP STEP 1" in buf.getvalue()
@@ -1047,6 +1047,11 @@ def test_sql_stamp_revision_as_kw(self):
             in buf.getvalue()
         )
 
+    def test_sql_stamp_base_does_not_drop_version_table(self):
+        with capture_context_buffer() as buf:
+            command.stamp(self.cfg, "base", sql=True)
+        assert "DROP TABLE alembic_version" not in buf.getvalue()
+
     def test_stamp_argparser_single_rev(self):
         cmd = config.CommandLine()
         options = cmd.parser.parse_args(["stamp", self.c, "--sql"])