diff --git a/neutron/common/_constants.py b/neutron/common/_constants.py
index e43d1c74c88..40745ecc86a 100644
--- a/neutron/common/_constants.py
+++ b/neutron/common/_constants.py
@@ -14,7 +14,6 @@
 # limitations under the License.
 
 from neutron_lib import constants
-from sqlalchemy.sql import elements
 
 # NOTE(boden): This module is common constants for neutron only.
 # Any constants used outside of neutron should go into neutron-lib.
@@ -93,6 +92,3 @@ METADATA_V6_CIDR = constants.METADATA_V6_IP + '/128'
 
 # TODO(haleyb): move this constant to neutron_lib.constants
 IPV4_MIN_MTU = 68
-
-# TODO(ralonsoh): move to neutron-lib.db.contants
-SQL_EMPTY_STRING = elements.TextClause("''")
diff --git a/neutron/db/models/dns.py b/neutron/db/models/dns.py
index 1bc95835deb..651a04275ec 100644
--- a/neutron/db/models/dns.py
+++ b/neutron/db/models/dns.py
@@ -16,7 +16,6 @@ import sqlalchemy as sa
 from sqlalchemy import orm
 from sqlalchemy import sql
 
-from neutron.common import _constants as n_const
 from neutron.db.models import l3 as l3_models
 from neutron.db import models_v2
 
@@ -86,7 +85,7 @@ class PortDNS(model_base.BASEV2):
     dns_name = sa.Column(sa.String(255), nullable=False)
     dns_domain = sa.Column(sa.String(constants.FQDN_FIELD_SIZE),
                            nullable=False,
-                           server_default=n_const.SQL_EMPTY_STRING)
+                           server_default='')
     # Add a relationship to the Port model in order to instruct
     # SQLAlchemy to eagerly load this association
     port = orm.relationship(models_v2.Port,
diff --git a/neutron/db/models_v2.py b/neutron/db/models_v2.py
index 11a9b76519c..789db0680c3 100644
--- a/neutron/db/models_v2.py
+++ b/neutron/db/models_v2.py
@@ -25,7 +25,6 @@ import sqlalchemy as sa
 from sqlalchemy import orm
 from sqlalchemy import sql
 
-from neutron.common import _constants as n_const
 from neutron.db.network_dhcp_agent_binding import models as ndab_model
 from neutron.db import rbac_db_models
 
@@ -297,8 +296,7 @@ class SubnetPool(standard_attr.HasStandardAttributes, model_base.BASEV2,
     is_default = sa.Column(sa.Boolean, nullable=False,
                            server_default=sql.false())
     default_quota = sa.Column(sa.Integer, nullable=True)
-    hash = sa.Column(sa.String(36), nullable=False,
-                     server_default=n_const.SQL_EMPTY_STRING)
+    hash = sa.Column(sa.String(36), nullable=False, server_default='')
     address_scope_id = sa.Column(sa.String(36), nullable=True, index=True)
     prefixes = orm.relationship(SubnetPoolPrefix,
                                 backref='subnetpools',
diff --git a/neutron/plugins/ml2/models.py b/neutron/plugins/ml2/models.py
index 78e6c05efa3..6061eaa1bd6 100644
--- a/neutron/plugins/ml2/models.py
+++ b/neutron/plugins/ml2/models.py
@@ -19,7 +19,6 @@ from neutron_lib.db import model_base
 import sqlalchemy as sa
 from sqlalchemy import orm
 
-from neutron.common import _constants as n_const
 from neutron.db.models import segment as segment_models
 from neutron.db import models_v2
 
@@ -46,10 +45,10 @@ class PortBinding(model_base.BASEV2):
                           default=portbindings.VNIC_NORMAL,
                           server_default=portbindings.VNIC_NORMAL)
     profile = sa.Column(sa.String(BINDING_PROFILE_LEN), nullable=False,
-                        default='', server_default=n_const.SQL_EMPTY_STRING)
+                        default='', server_default='')
     vif_type = sa.Column(sa.String(64), nullable=False)
     vif_details = sa.Column(sa.String(4095), nullable=False, default='',
-                            server_default=n_const.SQL_EMPTY_STRING)
+                            server_default='')
     status = sa.Column(sa.String(16), nullable=False,
                        default=constants.ACTIVE,
                        server_default=constants.ACTIVE)
@@ -116,12 +115,12 @@ class DistributedPortBinding(model_base.BASEV2):
     router_id = sa.Column(sa.String(36), nullable=True)
     vif_type = sa.Column(sa.String(64), nullable=False)
     vif_details = sa.Column(sa.String(4095), nullable=False, default='',
-                            server_default=n_const.SQL_EMPTY_STRING)
+                            server_default='')
     vnic_type = sa.Column(sa.String(64), nullable=False,
                           default=portbindings.VNIC_NORMAL,
                           server_default=portbindings.VNIC_NORMAL)
     profile = sa.Column(sa.String(BINDING_PROFILE_LEN), nullable=False,
-                        default='', server_default=n_const.SQL_EMPTY_STRING)
+                        default='', server_default='')
     status = sa.Column(sa.String(16), nullable=False)
 
     # Add a relationship to the Port model in order to instruct SQLAlchemy to