sqlalchemy.sql.schema.Sequence

class documentation

class Sequence(IdentityOptions, DefaultGenerator):

Represents a named database sequence.

The .Sequence object represents the name and configurational parameters of a database sequence. It also represents a construct that can be "executed" by a SQLAlchemy _engine.Engine or _engine.Connection, rendering the appropriate "next value" function for the target database and returning a result.

The .Sequence is typically associated with a primary key column:

some_table = Table(
    'some_table', metadata,
    Column('id', Integer, Sequence('some_table_seq'),
    primary_key=True)
)

When CREATE TABLE is emitted for the above _schema.Table, if the target platform supports sequences, a CREATE SEQUENCE statement will be emitted as well. For platforms that don't support sequences, the .Sequence construct is ignored.

See Also

:ref:`defaults_sequences`

.CreateSequence

.DropSequence

Method	`__init__`	Construct a `.Sequence` object.
Method	`_not_a_column_expr`	Undocumented
Method	`_set_metadata`	Undocumented
Method	`_set_parent`	Associate with this SchemaEvent's parent object.
Method	`_set_table`	Undocumented
Method	`create`	Creates this sequence in the database.
Method	`drop`	Drops this sequence from the database.
Method	`next_value`	Return a `.next_value` function element which will render the appropriate increment function for this `.Sequence` within any SQL expression.
Class Variable	`__visit_name__`	Undocumented
Class Variable	`is_sequence`	Undocumented
Instance Variable	`_key`	Undocumented
Instance Variable	`data_type`	Undocumented
Instance Variable	`metadata`	Undocumented
Instance Variable	`name`	Undocumented
Instance Variable	`optional`	Undocumented
Instance Variable	`schema`	Undocumented
Property	`bind`	Return the connectable associated with this default.
Property	`is_callable`	Undocumented
Property	`is_clause_element`	Undocumented

Inherited from IdentityOptions:

Instance Variable	`cache`	Undocumented
Instance Variable	`cycle`	Undocumented
Instance Variable	`increment`	Undocumented
Instance Variable	`maxvalue`	Undocumented
Instance Variable	`minvalue`	Undocumented
Instance Variable	`nomaxvalue`	Undocumented
Instance Variable	`nominvalue`	Undocumented
Instance Variable	`order`	Undocumented
Instance Variable	`start`	Undocumented

Inherited from DefaultGenerator:

Method	`_execute_on_connection`	Undocumented
Method	`execute`	Compile and execute this `.Executable`.
Class Variable	`is_server_default`	Undocumented
Instance Variable	`column`	Undocumented
Instance Variable	`for_update`	Undocumented

Inherited from Executable (via DefaultGenerator):

Method	`_add_context_option`	Add a context option to this statement.
Method	`_set_compile_options`	Assign the compile options to a new value.
Method	`_update_compile_options`	update the _compile_options with new keys.
Method	`execution_options`	Set non-SQL options for the statement which take effect during execution.
Method	`get_execution_options`	Get the non-SQL options which will take effect during execution.
Method	`options`	Apply options to this statement.
Method	`scalar`	Compile and execute this `.Executable`, returning the result's scalar representation.
Class Variable	`_bind`	Undocumented
Class Variable	`_executable_traverse_internals`	Undocumented
Class Variable	`_with_context_options`	Undocumented
Class Variable	`_with_options`	Undocumented
Class Variable	`is_delete`	Undocumented
Class Variable	`is_dml`	Undocumented
Class Variable	`is_insert`	Undocumented
Class Variable	`is_select`	Undocumented
Class Variable	`is_text`	Undocumented
Class Variable	`is_update`	Undocumented
Class Variable	`supports_execution`	Undocumented
Instance Variable	`_compile_options`	Undocumented
Instance Variable	`_execution_options`	Undocumented
Property	`_effective_plugin_target`	Undocumented

Inherited from StatementRole (via DefaultGenerator, Executable):

Class Variable	`_propagate_attrs`	Undocumented
Class Variable	`_role_name`	Undocumented

Inherited from SQLRole (via DefaultGenerator, Executable, StatementRole):

Class Variable	`allows_lambda`	Undocumented
Class Variable	`uses_inspection`	Undocumented

Inherited from Generative (via DefaultGenerator, Executable):

Method _generate Undocumented

Inherited from SchemaItem (via DefaultGenerator):

Method	`__repr__`	Undocumented
Method	`_init_items`	Initialize the list of child items for this SchemaItem.
Method	`_schema_item_copy`	Undocumented
Class Variable	`_use_schema_map`	Undocumented
Class Variable	`create_drop_stringify_dialect`	Undocumented
Property	`info`	Info dictionary associated with the object, allowing user-defined data to be associated with this `.SchemaItem`.

Inherited from SchemaEventTarget (via DefaultGenerator, SchemaItem):

Method _set_parent_with_dispatch Undocumented

Inherited from Traversible (via DefaultGenerator, SchemaItem):

Method	`get_children`	Return immediate child `.visitors.Traversible` elements of this `.visitors.Traversible`.
Method	`__class_getitem__`	Undocumented

def __init__(self, name, start=None, increment=None, minvalue=None, maxvalue=None, nominvalue=None, nomaxvalue=None, cycle=None, schema=None, cache=None, order=None, data_type=None, optional=False, quote=None, metadata=None, quote_schema=None, for_update=False):

overrides sqlalchemy.sql.schema.IdentityOptions.__init__

Construct a .Sequence object.

Parameters
name	the name of the sequence.
start	the starting index of the sequence. This value is used when the CREATE SEQUENCE command is emitted to the database as the value of the "START WITH" clause. If `None`, the clause is omitted, which on most platforms indicates a starting value of 1.
increment	the increment value of the sequence. This value is used when the CREATE SEQUENCE command is emitted to the database as the value of the "INCREMENT BY" clause. If `None`, the clause is omitted, which on most platforms indicates an increment of 1.
minvalue	the minimum value of the sequence. This value is used when the CREATE SEQUENCE command is emitted to the database as the value of the "MINVALUE" clause. If `None`, the clause is omitted, which on most platforms indicates a minvalue of 1 and -2^63-1 for ascending and descending sequences, respectively. New in version 1.0.7.
maxvalue	the maximum value of the sequence. This value is used when the CREATE SEQUENCE command is emitted to the database as the value of the "MAXVALUE" clause. If `None`, the clause is omitted, which on most platforms indicates a maxvalue of 2^63-1 and -1 for ascending and descending sequences, respectively. New in version 1.0.7.
nominvalue	no minimum value of the sequence. This value is used when the CREATE SEQUENCE command is emitted to the database as the value of the "NO MINVALUE" clause. If `None`, the clause is omitted, which on most platforms indicates a minvalue of 1 and -2^63-1 for ascending and descending sequences, respectively. New in version 1.0.7.
nomaxvalue	no maximum value of the sequence. This value is used when the CREATE SEQUENCE command is emitted to the database as the value of the "NO MAXVALUE" clause. If `None`, the clause is omitted, which on most platforms indicates a maxvalue of 2^63-1 and -1 for ascending and descending sequences, respectively. New in version 1.0.7.
cycle	allows the sequence to wrap around when the maxvalue or minvalue has been reached by an ascending or descending sequence respectively. This value is used when the CREATE SEQUENCE command is emitted to the database as the "CYCLE" clause. If the limit is reached, the next number generated will be the minvalue or maxvalue, respectively. If cycle=False (the default) any calls to nextval after the sequence has reached its maximum value will return an error. New in version 1.0.7.
schema	optional schema name for the sequence, if located in a schema other than the default. The rules for selecting the schema name when a `_schema.MetaData` is also present are the same as that of :paramref:`_schema.Table.schema`.
cache	optional integer value; number of future values in the sequence which are calculated in advance. Renders the CACHE keyword understood by Oracle and PostgreSQL. New in version 1.1.12.
order	optional boolean value; if `True`, renders the ORDER keyword, understood by Oracle, indicating the sequence is definitively ordered. May be necessary to provide deterministic ordering using Oracle RAC. New in version 1.1.12.
data_type	The type to be returned by the sequence, for dialects that allow us to choose between INTEGER, BIGINT, etc. (e.g., mssql). New in version 1.4.0.
optional	boolean value, when `True`, indicates that this `.Sequence` object only needs to be explicitly generated on backends that don't provide another way to generate primary key identifiers. Currently, it essentially means, "don't create this sequence on the PostgreSQL backend, where the SERIAL keyword creates a sequence for us automatically".
quote	boolean value, when `True` or `False`, explicitly forces quoting of the :paramref:`_schema.Sequence.name` on or off. When left at its default of `None`, normal quoting rules based on casing and reserved words take place.
metadata	optional `_schema.MetaData` object which this `.Sequence` will be associated with. A `.Sequence` that is associated with a `_schema.MetaData` gains the following capabilities: The `.Sequence` will inherit the :paramref:`_schema.MetaData.schema` parameter specified to the target `_schema.MetaData`, which affects the production of CREATE / DROP DDL, if any. The `.Sequence.create` and `.Sequence.drop` methods automatically use the engine bound to the `_schema.MetaData` object, if any. The `_schema.MetaData.create_all` and `_schema.MetaData.drop_all` methods will emit CREATE / DROP for this `.Sequence`, even if the `.Sequence` is not associated with any `_schema.Table` / `_schema.Column` that's a member of this `_schema.MetaData`. The above behaviors can only occur if the `.Sequence` is explicitly associated with the `_schema.MetaData` via this parameter. See Also :ref:`sequence_metadata` - full discussion of the :paramref:`.Sequence.metadata` parameter.
quote_schema	Set the quoting preferences for the `schema` name.
for_update	Indicates this `.Sequence`, when associated with a `_schema.Column`, should be invoked for UPDATE statements on that column's table, rather than for INSERT statements, when no value is otherwise present for that column in the statement.

def _not_a_column_expr(self):

Undocumented

def _set_metadata(self, metadata):

Undocumented

def _set_parent(self, column, **kw):

overrides sqlalchemy.sql.schema.DefaultGenerator._set_parent

Associate with this SchemaEvent's parent object.

def _set_table(self, column, table):

Undocumented

def create(self, bind=None, checkfirst=True):

Creates this sequence in the database.

Note

the "bind" argument will be required in SQLAlchemy 2.0.

def drop(self, bind=None, checkfirst=True):

Drops this sequence from the database.

Note

the "bind" argument will be required in SQLAlchemy 2.0.

@util.preload_module('sqlalchemy.sql.functions')
def next_value(self):

Return a .next_value function element which will render the appropriate increment function for this .Sequence within any SQL expression.

__visit_name__: str =

overrides sqlalchemy.sql.schema.DefaultGenerator.__visit_name__

Undocumented

is_sequence: bool =

overrides sqlalchemy.sql.schema.DefaultGenerator.is_sequence

Undocumented

_key =

Undocumented

data_type =

Undocumented

metadata =

Undocumented

name =

Undocumented

optional =

Undocumented

schema =

Undocumented

@property
bind =

overrides sqlalchemy.sql.schema.DefaultGenerator.bind

Return the connectable associated with this default.

@util.memoized_property
is_callable =

Undocumented

@util.memoized_property
is_clause_element =

Undocumented