how to set row number with in sqlalchemy

A hacky way of doing it without the ROW_NUMBER function (not present in MySQL server < 8.0):

session.execute('SET @row_number = 0')
query = session.query(product).order_by('IDX')
row_number_column = "(@row_number:=@row_number + 1) AS row_num"
query = query.add_column(row_number_column)

The "invalid" SQL part is:

row_number() OVER(ORDER BY product.IDX) AS ROW_NUM

Suggestion : 2

sqlalchemy.func.sum() , sqlalchemy.func.count() , sqlalchemy.ext.declarative

def query(self, source, target, core, column, pkey):
   # Get all POIs of fclass `on`
pois = select(
   [source.c[self.source_id], source.c.WKT],
   source.c[self.source_column] == self.source_filter,
).cte("pois")
# Compute the distance from `column`
to each POI within given distance
distance = func.ST_Distance(
   core.ST_GeoFromText(target.c[column]),
   core.ST_GeoFromText(pois.c.WKT),
)
pairs = (
   select(
      [target, distance.label(self.feature_name)],
      distance < self.within,
   )
   .select_from(pois)
   .cte("pairs")
)
# Partition results to get the smallest distance(nearest POI)
query = select(
   [
      pairs,
      func.row_number()
      .over(
         partition_by = pairs.c[pkey],
         order_by = pairs.c[self.feature_name].asc(),
      )
      .label("row_number"),
   ]
).select_from(pairs)
query = select(
   [col
      for col in query.columns
      if col.key != "row_number"
   ],
   query.c["row_number"] == 1,
)
return query

def over(self, partition_by = None, order_by = None, rows = None, range_ = None):
   ""
"Produce an OVER clause against this function.

Used against aggregate or so - called "window"
functions,
for database backends that support window functions.

The expression::

   func.row_number().over(order_by = 'x')

is shorthand
for::

from sqlalchemy
import over
over(func.row_number(), order_by = 'x')

See: func: `_expression.over`
for a full description.

""
"
return Over(
   self,
   partition_by = partition_by,
   order_by = order_by,
   rows = rows,
   range_ = range_,
)

def test_over_invalid_framespecs(self):
   assert_raises_message(
      exc.ArgumentError,
      "Integer or None expected for range value",
      func.row_number().over,
      range_ = ("foo", 8),
   )

assert_raises_message(
   exc.ArgumentError,
   "Integer or None expected for range value",
   func.row_number().over,
   range_ = (-5, "foo"),
)

assert_raises_message(
   exc.ArgumentError,
   "'range_' and 'rows' are mutually exclusive",
   func.row_number().over,
   range_ = (-5, 8),
   rows = (-2, 5),
)

def test_clause_expansion(self):
   Data = self.classes.Data

b1 = Bundle("b1", Data.id, Data.d1, Data.d2)

sess = Session()
self.assert_compile(
   sess.query(Data).order_by(b1),
   "SELECT data.id AS data_id, data.d1 AS data_d1, "
   "data.d2 AS data_d2, data.d3 AS data_d3 FROM data "
   "ORDER BY data.id, data.d1, data.d2",
)

self.assert_compile(
   sess.query(func.row_number().over(order_by = b1)),
   "SELECT row_number() OVER (ORDER BY data.id, data.d1, data.d2) "
   "AS anon_1 FROM data",
)

def __init__(self, func, partition_by = None, order_by = None):
   ""
"Produce an :class:`.Over` object against a function.

Used against aggregate or so - called "window"
functions,
for database backends that support window functions.

E.g.::

   from sqlalchemy
import over
over(func.row_number(), order_by = 'x')

Would produce "ROW_NUMBER() OVER(ORDER BY x)".

   : param func: a: class: `.FunctionElement`
construct, typically
generated by: data: `~.expression.func`.: param partition_by: a column element or string, or a list of such, that will be used as the PARTITION BY clause of the OVER construct.: param order_by: a column element or string, or a list of such, that will be used as the ORDER BY clause of the OVER construct.

This
function is also available from the: data: `~.expression.func`
construct itself via the: meth: `.FunctionElement.over`
method.

   ..versionadded::0.7

""
"
self.func = func
if order_by is not None:
   self.order_by = ClauseList( *
      util.to_list(order_by),
      _literal_as_text = _literal_as_label_reference)
if partition_by is not None:
   self.partition_by = ClauseList( *
      util.to_list(partition_by),
      _literal_as_text = _literal_as_label_reference)

def get_storage_at_block(cls, current_session, block_number):
   ""
"
Gives the storage values at requested block

   : param int block_number: Block number of desired storage, always
required since it is called from method `State.get_state_at_block`
""
"
row_number_column = func.row_number().over(
      partition_by = [StorageDiff.address, StorageDiff.position],
      order_by = [StorageDiff.block_number.desc(),
         StorageDiff.transaction_index.desc()
      ])\
   .label('row_number')
query = current_session.db_session.query(StorageDiff.address, StorageDiff.position, StorageDiff.storage_to.label('storage'))
query = query.add_column(row_number_column)
query = query.filter(
   and_(
      StorageDiff.block_number <= block_number,
      StorageDiff.storage_to != '0x0000000000000000000000000000000000000000000000000000000000000000'))
query = query.from_self().filter(row_number_column == 1)

for row in query:
   if row.storage is not None:
   if hex_to_integer(row.storage) != 0:
   storage = cls.add_storage(address = row.address, position = row.position, storage = row.storage)
else:
   # not adding storage positions where value is 0, since parity discards these positions during
export
logger.debug('address: {}, position {}, storage: {} is zero'.format(row.address, row.position, row.storage))
current_session.db_session.add(storage)
else:
   logger.debug('address: {}, position {}, storage: {} is none'.format(row.address, row.position, row.storage))

Suggestion : 3

Setting the COLUMNS and FROM clause Selecting ORM Entities and Columns Selecting from Labeled SQL Expressions Selecting with Textual Column Expressions ,Approaches towards selecting ORM entities and columns as well as common methods for converting rows are discussed further at Selecting ORM Entities and Attributes.,The select() SQL Expression Construct,Alternatively, we can select individual columns of an ORM entity as distinct elements within result rows, by using the class-bound attributes; when these are passed to a construct such as select(), they are resolved into the Column or other SQL expression represented by each attribute:

>>> from sqlalchemy
import select
   >>>
   stmt = select(user_table).where(user_table.c.name == 'spongebob') >>>
   print(stmt)
SELECT user_account.id, user_account.name, user_account.fullname
FROM user_account
WHERE user_account.name =: name_1

>>> with engine.connect() as conn:
   ...
   for row in conn.execute(stmt):
   ...print(row)
BEGIN(implicit)
SELECT user_account.id, user_account.name, user_account.fullname
FROM user_account
WHERE user_account.name = ? [...]('spongebob', )
   (1, 'spongebob', 'Spongebob Squarepants')
ROLLBACK

>>> stmt = select(User).where(User.name == 'spongebob') >>>
   with Session(engine) as session:
   ...
   for row in session.execute(stmt):
   ...print(row)
BEGIN(implicit)
SELECT user_account.id, user_account.name, user_account.fullname
FROM user_account
WHERE user_account.name = ? [...]('spongebob', )
   (User(id = 1, name = 'spongebob', fullname = 'Spongebob Squarepants'), )
ROLLBACK

>>> print(select(user_table))
SELECT user_account.id, user_account.name, user_account.fullname
FROM user_account

>>> print(select(user_table.c.name, user_table.c.fullname))
SELECT user_account.name, user_account.fullname
FROM user_account

>>> print(select(User))
SELECT user_account.id, user_account.name, user_account.fullname
FROM user_account

Suggestion : 4

A hacky way of doing it without the anycodings_python ROW_NUMBER function (not present in anycodings_python MySQL server < 8.0):,There are some workarounds, but those anycodings_python are ugly and not generated automatically anycodings_python by SQL Alchemy.,I propose to either upgrade your MySQL anycodings_python or MariaDB server, or to instead count anycodings_python up the row number on Python side while anycodings_python iterating over the result.,You are using a database feature not anycodings_python present in your MySQL version.

with in python 3.6.5 SQLAlchemy==1.2.15 aws anycodings_sql rds

query = session.query(product)
row_number_column = func.row_number().over(order_by = 'IDX').label('row_num')
query = query.add_column(row_number_column)

A hacky way of doing it without the anycodings_python ROW_NUMBER function (not present in anycodings_python MySQL server < 8.0):

session.execute('SET @row_number = 0')
query = session.query(product).order_by('IDX')
row_number_column = "(@row_number:=@row_number + 1) AS row_num"
query = query.add_column(row_number_column)

The "invalid" SQL part is:

row_number() OVER(ORDER BY product.IDX) AS ROW_NUM

Suggestion : 5

Python

 def test_over(self):
    eq_(
       select([
          flds.c.intcol, func.row_number().over(order_by = flds.c.strcol)
       ]).execute().fetchall(),
       [(13, 1), (5, 2)]
    )

def column_windows(session, column, windowsize):
   ""
"Return a series of WHERE clauses against
a given column that
break it into windows.

Result is an iterable of tuples, consisting of
   ((start, end), whereclause), where(start, end) are the ids.
""
"

def int_for_range(start_id, end_id):
   "create a range"
if end_id:
   return and_(column >= start_id, column < end_id)
else:
   return column >= start_id

qry = session.query(column,
   func.row_number().over(order_by = column).label('rownum')
).from_self(column)

if windowsize > 1:
   qry = qry.filter("rownum %% %d=1" % windowsize)

intervals = [qid
   for qid, in qry
]

while intervals:
   start = intervals.pop(0)
if intervals:
   end = intervals[0]
else:
   end = None
yield int_for_range(start, end)

    def top_players(self):
       ""
    "Top players on this server by total playing time."
    ""
    try:
    top_players_q = DBSession.query(
          fg.row_number().over(
             order_by = expr.desc(func.sum(PlayerGameStat.alivetime))).label("rank"),
          Player.player_id, Player.nick,
          func.sum(PlayerGameStat.alivetime).label("alivetime"))\
       .filter(Player.player_id == PlayerGameStat.player_id)\
       .filter(Game.game_id == PlayerGameStat.game_id)\
       .filter(Game.server_id == self.server_id)\
       .filter(Player.player_id > 2)\
       .filter(PlayerGameStat.create_dt > (self.now - timedelta(days = self.lifetime)))\
       .order_by(expr.desc(func.sum(PlayerGameStat.alivetime)))\
       .group_by(Player.nick)\
       .group_by(Player.player_id)

    if self.last:
       top_players_q = top_players_q.offset(self.last)

    if self.limit:
       top_players_q = top_players_q.limit(self.limit)

    top_players = top_players_q.all()

    except Exception as e:
       log.debug(e)
    raise HTTPNotFound

    return top_players

    def get_top_scorers(self):
       ""
    "Top players by score. Shared by all renderers."
    ""
    cutoff = self.now - timedelta(days = self.lifetime)
    cutoff = self.now - timedelta(days = 120)

    top_scorers_q = DBSession.query(
          fg.row_number().over(order_by = expr.desc(func.sum(PlayerGameStat.score))).label("rank"),
          Player.player_id, Player.nick, func.sum(PlayerGameStat.score).label("total_score"))\
       .filter(Player.player_id == PlayerGameStat.player_id)\
       .filter(Game.game_id == PlayerGameStat.game_id)\
       .filter(Game.map_id == self.map_id)\
       .filter(Player.player_id > 2)\
       .filter(PlayerGameStat.create_dt > cutoff)\
       .order_by(expr.desc(func.sum(PlayerGameStat.score)))\
       .group_by(Player.nick)\
       .group_by(Player.player_id)

    if self.last:
       top_scorers_q = top_scorers_q.offset(self.last)

    if self.limit:
       top_scorers_q = top_scorers_q.limit(self.limit)

    top_scorers = top_scorers_q.all()

    return top_scorers

    def top_maps(self):
       ""
    "Returns the raw data shared by all renderers."
    ""
    try:
    top_maps_q = DBSession.query(
          fg.row_number().over(order_by = expr.desc(func.count())).label("rank"),
          Game.map_id, Map.name, func.count().label("times_played"))\
       .filter(Map.map_id == Game.map_id)\
       .filter(Game.server_id == self.server_id)\
       .filter(Game.create_dt > (self.now - timedelta(days = self.lifetime)))\
       .group_by(Game.map_id)\
       .group_by(Map.name)\
       .order_by(expr.desc(func.count()))

    if self.last:
       top_maps_q = top_maps_q.offset(self.last)

    if self.limit:
       top_maps_q = top_maps_q.limit(self.limit)

    top_maps = top_maps_q.all()
    except Exception as e:
       log.debug(e)
    raise HTTPNotFound

    return top_maps

    def test_over(self):
       stmt = select([column("foo"), column("bar")])
    stmt = select(
       [func.row_number().over(order_by = "foo", partition_by = "bar")]
    ).select_from(stmt)

    self.assert_compile(
       stmt,
       "SELECT row_number() OVER (PARTITION BY bar ORDER BY foo) "
       "AS anon_1 FROM (SELECT foo, bar)",
    )

Suggestion : 6

In this chapter, we will discuss about the concept of selecting rows in the table object.,Here, we have to note that select object can also be obtained by select() function in sqlalchemy.sql module. The select() function requires the table object as argument.,We can use this select object as a parameter to execute() method of connection object as shown in the code below −,The select() method of table object enables us to construct SELECT expression.

The select() method of table object enables us to construct SELECT expression.

s = students.select()

The select object translates to SELECT query by str(s) function as shown below −

'SELECT students.id, students.name, students.lastname FROM students'

We can use this select object as a parameter to execute() method of connection object as shown in the code below −

result = conn.execute(s)

The resultant variable is an equivalent of cursor in DBAPI. We can now fetch records using fetchone() method.

row = result.fetchone()

All selected rows in the table can be printed by a for loop as given below −

for row in result:
   print(row)

Suggestion : 7

We’ll be using the basic functionality of SQLAlchemy which is the SQL Expression Language to create some metadata that will contain a number of related modules (or objects) that define our new book database table:,With the engine created, we now need to use the .create_all() method of our metadata object and pass the engine connection to it, which will automatically cause SQLAlchemy to generate our table for us, as seen above.,In addition to create_engine, we’re also importing a number of additional modules that we’ll need for creating a new table. Before we get to that though, ensure SQLAlchemy was installed, imported, and is working by calling .__version__ like so:,Once our table(s) are defined and associated with our metadata object, we need to create a database engine with which we can connect. This is accomplished using the create_engine function.

import sqlalchemy
from sqlalchemy
import create_engine
from sqlalchemy
import Table, Column, Integer, String, MetaData, ForeignKey
from sqlalchemy
import inspect

print sqlalchemy.__version__
Out[ * ]: 1.0 .9

metadata = MetaData()
books = Table('book', metadata,
   Column('id', Integer, primary_key = True),
   Column('title', String),
   Column('primary_author', String),
)

engine = create_engine('sqlite:///bookstore.db')
metadata.create_all(engine)

engine = create_engine('sqlite:///bookstore.db')

engine = create_engine('postgresql://user:password@host/database')

inspector = inspect(engine)
inspector.get_columns('book')
Out[ * ]: [{
      'autoincrement': True,
      'default': None,
      'name': u 'id',
      'nullable': False,
      'primary_key': 1,
      'type': INTEGER()
   },
   {
      'autoincrement': True,
      'default': None,
      'name': u 'title',
      'nullable': True,
      'primary_key': 0,
      'type': VARCHAR()
   },
   {
      'autoincrement': True,
      'default': None,
      'name': u 'primary_author',
      'nullable': True,
      'primary_key': 0,
      'type': VARCHAR()
   }
]