diff --git a/dvc/dependency/db.py b/dvc/dependency/db.py
index 8655ff21e..cdbfcbeb5 100644
--- a/dvc/dependency/db.py
+++ b/dvc/dependency/db.py
@@ -44,6 +44,10 @@ class AbstractDependency(Dependency):
         self.def_path = None  # type: ignore[assignment]
         self.info = info or {}
 
+    @property
+    def is_in_repo(self):
+        return False
+
 
 class DbDependency(AbstractDependency):
     PARAM_CONNECTION = "connection"
@@ -70,8 +74,8 @@ class DbDependency(AbstractDependency):
         return self.db_info.get(self.PARAM_QUERY) or self.db_info.get(self.PARAM_TABLE)
 
     def __repr__(self):
-        return "{}:{}".format(
-            self.__class__.__name__, "".join(f"{k}=={v}" for k, v in self.info.items())
+        return "{}: {}".format(
+            self.__class__.__name__, "".join(f"{k}={v}" for k, v in self.info.items())
         )
 
     def __str__(self):
diff --git a/dvc/repo/experiments/serialize.py b/dvc/repo/experiments/serialize.py
index e4d2b96c2..6c9921d4f 100644
--- a/dvc/repo/experiments/serialize.py
+++ b/dvc/repo/experiments/serialize.py
@@ -50,7 +50,12 @@ class SerializableExp:
         Params, metrics, deps, outs are filled via repo fs/index, all other fields
         should be passed via kwargs.
         """
-        from dvc.dependency import ParamsDependency, RepoDependency
+        from dvc.dependency import (
+            DatasetDependency,
+            DbDependency,
+            ParamsDependency,
+            RepoDependency,
+        )
 
         rev = rev or repo.get_rev()
         assert rev
@@ -68,7 +73,10 @@ class SerializableExp:
                     nfiles=dep.meta.nfiles if dep.meta else None,
                 )
                 for dep in repo.index.deps
-                if not isinstance(dep, (ParamsDependency, RepoDependency))
+                if not isinstance(
+                    dep,
+                    (ParamsDependency, RepoDependency, DatasetDependency, DbDependency),
+                )
             },
             outs={
                 relpath(out.fs_path, repo.root_dir): ExpOut(
diff --git a/dvc/stage/run.py b/dvc/stage/run.py
index d193b1b0e..758fc427a 100644
--- a/dvc/stage/run.py
+++ b/dvc/stage/run.py
@@ -154,7 +154,11 @@ def cmd_run(stage, dry=False, run_env=None):
 
 
 def _pull_missing_deps(stage):
+    from dvc.dependency import DatasetDependency, DbDependency
+
     for dep in stage.deps:
+        if isinstance(dep, (DatasetDependency, DbDependency)):
+            continue
         if not dep.exists:
             stage.repo.pull(dep.def_path)