如何在SQLAlchemy中插入t1(SELECT*FROM t2)？

Question

在SQLAlchemy中,如何从SELECT语句中填充或更新表？

Answer 1

SQLalchemy不会为您构建此构造.您可以使用文本中的查询.

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

编辑:

一年多以后,但现在在sqlalchemy 0.6+上你可以创建它:

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

生产:

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

另一个编辑:

现在,4年后,语法被合并到SQLAlchemy 0.9中,并向后移植到0.8.3; 您可以创建任何select()然后使用对象的新from_select()方法Insert:

>>> 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

更多信息在文档中.

Answer 2

从0.8.3开始,您现在可以直接在sqlalchemy中执行此操作:Insert.from_select:

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