Question: I have workspacestable workspaces_table = Table( "workspaces", metadata_obj, Column("id", UUID(as_uuid=False), primary_key=True, default=uuid.uuid4), Column("name", JSONB(), nullable=False), Column("created_at", TIMESTAMP(timezone=False), default=datetime.datetime.now(), nullable=False), Column("updated_at", TIMESTAMP(timezone=False), default=datetime.datetime.now(), nullable=False), Column("created_by", UUID(as_uuid=False), ForeignKey('users.id'), nullable=False), Column("updated_by", UUID(as_uuid=False), ForeignKey('users.id'), nullable=False), Column("email", Text(), nullable=False) )  In this table columns created_at and updated_at have default value datetime.datetime.now() But when I try to insert row in this table like  await conn.execute(text( f""" WITH workspace_create AS ( INSERT INTO workspaces(id, name, created_by, updated_by, email) VALUES (:workspace_id, :workspace_name, :user_id, :user_id, :workspace_email) ), workspace_roles_create AS ( INSERT INTO workspace_roles(id, name, export_data, users, settings, projects, roles, system_name, workspace_id) VALUES {sql_query_workspace_roles_values} ) INSERT INTO m2m_users_to_workspace_or_project_roles(user_id, role_id, role_type, user_status) VALUES(:user_id, :superuser_id, '{RoleTypes.Workspace.name}', '{UserStatuses.Active.name}') """ ), params )  I get following error: null value in column "created_at" of relation "workspaces" violates not-null constraint DETAIL: Failing row contains (dd31dfb6-6d22-4794-b804-631e60b6e063, [{"locale": "ru", "text_value": "ru_team_1"}], null, null, 481b7a55-52b7-48f2-89ea-4ae0673d4ab6, 481b7a55-52b7-48f2-89ea-4ae0673d4ab6, ruslpogo@gmail.com).  I see that row contains null instead default value in created_at updated_at columns. How can I insert default values automatically?

Answer: Column(…, default=…) is a client-side default value that is used by SQLAlchemy Core (and SQLAlchemy ORM) when you do something like workspaces_table.insert(). Note that if SQLAlchemy creates the table then that column does not have a server-side DEFAULT: workspaces_table = Table( "workspaces", MetaData(), Column("id", Integer(), primary_key=True), Column("created_at", DateTime(), default=datetime.now()), ) engine.echo = False workspaces_table.drop(engine, checkfirst=True) engine.echo = True workspaces_table.create(engine) """ DDL emitted: CREATE TABLE workspaces ( id SERIAL NOT NULL, created_at TIMESTAMP WITHOUT TIME ZONE, PRIMARY KEY (id) ) """  Column(…, server_default=…) is what specifies the server-side DEFAULT which will be available to plain text INSERT statements like the one in your question: workspaces_table = Table( "workspaces", MetaData(), Column("id", Integer(), primary_key=True), Column("created_at", DateTime(), server_default=text("CURRENT_TIMESTAMP")), ) engine.echo = False workspaces_table.drop(engine, checkfirst=True) engine.echo = True workspaces_table.create(engine) """ DDL emitted: CREATE TABLE workspaces ( id SERIAL NOT NULL, created_at TIMESTAMP WITHOUT TIME ZONE DEFAULT CURRENT_TIMESTAMP, PRIMARY KEY (id) ) """  Note that changing the Table() definition from default= to server_default= will not update an existing table; you'll need to use ALTER TABLE for that.