如何在SQLAlchemy中插入t1（SELECT * FROM t2）？

Question

在SQLAlchemy中，如何填充或更新SELECT語句中的表格？

Answer 1

SQLalchemy不會爲您構建此構造。您可以使用來自文本的查詢。

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

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編輯：

一年多過去了，但現在對SQLAlchemy的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 

產地：

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

---

另一個編輯：

現在，4年後，語法被納入SQLAlchemy 0.9，並backported到0.8.3;您可以創建任意select()然後用Insert對象的新from_select()方法：

>>> 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

由於Noslko在評論中指出，現在你可以擺脫原始的SQL的： 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 

產地：

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

Answer 3

由於0.8。 3，您現在可以直接在sqlalchemy中執行此操作：Insert.from_select：

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