Fetch table values using alembic and update to another table.

Finally I solved the problem. Created raw sql to fetch the values and used bulk_insert.

def upgrade():
    ### commands auto generated by Alembic - please adjust! ###
    op.create_table('client_credential',
    sa.Column('id', sa.Integer(), nullable=False),
    sa.Column('created_at', sa.DateTime(), nullable=False),
    sa.Column('updated_at', sa.DateTime(), nullable=False),
    sa.Column('client_id', sa.Integer(), nullable=False),
    sa.Column('key', sa.String(length=22), nullable=False),
    sa.Column('secret', sa.String(length=44), nullable=False),
    sa.Column('is_active', sa.Boolean(), nullable=False),
    sa.ForeignKeyConstraint(['client_id'], ['client.id'], ),
    sa.PrimaryKeyConstraint('id'),
    sa.UniqueConstraint('key')
    )
    #http://stackoverflow.com/questions/15725859/sqlalchemy-alembic-bulk-insert-fails-str-object-has-no-attribute-autoincre
    client_credential = sa.sql.table('client_credential',
        sa.Column('client_id', sa.Integer, nullable=False),
        sa.Column('is_active', sa.Boolean, nullable=False, default=True),
        sa.Column('key', sa.String(22), nullable=False, default=True),
        sa.Column('secret', sa.String(22), nullable=False, default=True),
        sa.Column('created_at', sa.DateTime, nullable=False, default=sa.func.now()),
        sa.Column('updated_at', sa.DateTime, nullable=False, default=sa.func.now()),
    )
    conn = op.get_bind()
    res = conn.execute("select secret, key, id from client")
    results = res.fetchall()
    clients = [{'secret': r[0], 'key': r[1], 'is_active':True, 'client_id': r[2], 'created_at': datetime.datetime.now(), 'updated_at': datetime.datetime.now()} for r in results]
    op.bulk_insert(client_credential, clients)
    op.drop_column(u'client', u'secret')
    op.drop_column(u'client', u'key')
    ### end Alembic commands ###