Come INSERIRE IN t1 (SELECT * FROM t2) in SQLAlchemy?

Question

In SQLAlchemy, come faccio a popolare o aggiornare una tabella da una dichiarazione SELECT?

Answer 1

SQLalchemy non crea questo costrutto per te. È possibile utilizzare la query dal testo.

session.execute('INSERT INTO t1 (SELECT * FROM t2)') 

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EDIT:

Più di un anno dopo, ma d'ora in poi sqlalchemy 0.6+ you can create it:

from sqlalchemy.ext import compiler 
from sqlalchemy.sql.expression import Executable, ClauseElement 

class InsertFromSelect(Executable, ClauseElement): 
    def __init__(self, table, select): 
     self.table = table 
     self.select = select 

@compiler.compiles(InsertFromSelect) 
def visit_insert_from_select(element, compiler, **kw): 
    return "INSERT INTO %s (%s)" % (
     compiler.process(element.table, asfrom=True), 
     compiler.process(element.select) 
    ) 

insert = InsertFromSelect(t1, select([t1]).where(t1.c.x>5)) 
print insert 

produce:

"INSERT INTO mytable (SELECT mytable.x, mytable.y, mytable.z FROM mytable WHERE mytable.x > :x_1)" 

---

Un altro MODIFICA:

Ora, 4 anni dopo, la sintassi è incorporata in SQLAlchemy 0.9 e backportata a 0.8.3; È possibile creare qualsiasi select() e quindi utilizzare il nuovo metodo di from_select()Insert oggetti:

>>> from sqlalchemy.sql import table, column 
>>> t1 = table('t1', column('a'), column('b')) 
>>> t2 = table('t2', column('x'), column('y')) 
>>> print(t1.insert().from_select(['a', 'b'], t2.select().where(t2.c.y == 5))) 
INSERT INTO t1 (a, b) SELECT t2.x, t2.y 
FROM t2 
WHERE t2.y = :y_1 

More information in the docs.

Answer 2

Come Noslko sottolineato in commento, ora è possibile sbarazzarsi di SQL prime: http://www.sqlalchemy.org/docs/core/compiler.html#compiling-sub-elements-of-a-custom-expression-construct

from sqlalchemy.ext.compiler import compiles 
from sqlalchemy.sql.expression import Executable, ClauseElement 

class InsertFromSelect(Executable, ClauseElement): 
    def __init__(self, table, select): 
     self.table = table 
     self.select = select 

@compiles(InsertFromSelect) 
def visit_insert_from_select(element, compiler, **kw): 
    return "INSERT INTO %s (%s)" % (
     compiler.process(element.table, asfrom=True), 
     compiler.process(element.select) 
    ) 

insert = InsertFromSelect(t1, select([t1]).where(t1.c.x>5)) 
print insert 

produce:

INSERT INTO mytable (SELECT mytable.x, mytable.y, mytable.z FROM mytable WHERE mytable.x > :x_1) 

Answer 3

Come di 0,8. 3, ora puoi farlo direttamente in sqlalchemy: Insert.from_select:

sel = select([table1.c.a, table1.c.b]).where(table1.c.c > 5) 
ins = table2.insert().from_select(['a', 'b'], sel)