constraints - sqlalchemy python update a primary key with foreign key restraints -

i need change primary key in multiple tables have foreign key restraints. thinking either update or copy entry updated primary key , delete old entry. how can accomplish either?

below minimal working set of tables. p , s rely on primary key of s , s relies on primary key of h.

i need update value of ever table 1 entry. continually limited on changing value because of constraints. rather not remove constraints can permanent solution later use.

class h(base):     __tablename__ = 'ch'     = column(string(255), nullable=false, primary_key=true)     other_columns = column(string(255))  class s(base):     __tablename__ = 'cs'     = column(string(255), foreignkey('ch.a'), nullable=false, primary_key=true)     sn = column(integer, nullable=false, primary_key=true)     other_columns = column(date)     header = relationship("h", backref=backref('cs', order_by=a, cascade='delete, all, delete-orphan'), foreign_keys='s.a')     __table_args__ = (uniqueconstraint('a', 'sn', name='_a_sn_uc'),)  class p(base):     __tablename__ = 'cs_p'     = column(string(255), nullable=false, primary_key=true)     sn = column(integer, nullable=false, primary_key=true)     ps = column(integer, nullable=false, primary_key=true)     other_columns = column(string(255))     pa = relationship("s", backref=backref('cs_p', order_by=a, cascade='delete, all, delete-orphan'))     __table_args__ = (uniqueconstraint('a', 'sn', 'ps', name='_a_sn_ps_uc'),                       foreignkeyconstraint([a, sn], [s.a, s.sn]),)  class f(base):     __tablename__ = 'cs_f'     = column(string(255), nullable=false, primary_key=true)     sn = column(integer, nullable=false, primary_key=true)     fs = column(integer, nullable=false, primary_key=true)     other_columns = column(string(255))     fa = relationship("s", backref=backref('cs_f', order_by=a, cascade='delete, all, delete-orphan'))     __table_args__ = (uniqueconstraint('a', 'sn', 'fs', name='_a_sn_fs_uc'),                       foreignkeyconstraint([a, sn], [s.a, s.sn]),)