Getting COUNT from sqlalchemy

Question

I have:

res = db.engine.execute(\'select count(id) from sometable\')

The returned object is sqlalchemy.engine.result.ResultProxy

Answer 1

While the other answers work, SQLAlchemy provides a shortcut for scalar queries as ResultProxy.scalar():

count = db.engine.execute('select count(id) from sometable').scalar()

scalar() fetches the first column of the first row and closes the result set, or returns None if no row is present. There's also Query.scalar(), if using the Query API.

Answer 2

what you are asking for called unpacking, ResultProxy is an iterable, so we can do

# there will be single record
record, = db.engine.execute('select count(id) from sometable')
# this record consist of single value
count, = record

Answer 3

The ResultProxy in SQLAlchemy (as documented here http://docs.sqlalchemy.org/en/latest/core/connections.html?highlight=execute#sqlalchemy.engine.ResultProxy) is an iterable of the columns returned from the database. For a count() query, simply access the first element to get the column, and then another index to get the first element (and only) element of that column.

result = db.engine.execute('select count(id) from sometable')
count = result[0][0]

If you happened to be using the ORM of SQLAlchemy, I would suggest using the Query.count() method on the appropriate model as shown here: http://docs.sqlalchemy.org/en/latest/orm/query.html?highlight=count#sqlalchemy.orm.query.Query.count