common iter query，commoniter,def iquery(c

common iter query，commoniter,def iquery(c

def iquery(conn, sql, rowfactory=tuple, batch=1, *args, **kwgs):    """在给定的数据库连接conn上执行sql(可带有参数*args或命名参数**kwgs)    rowfactory指定输出物为元组/字典(或字典的扩展类)        /或使用用命名参数的函数的结果    batch <= 0时, 直接全部输出    batch == 1时, 逐记录输出    batch >= 1时, 按指定的数量形成批次列表    """    from itertools import imap    from contextlib import closing    with closing(conn.cursor()) as curr:        if curr.execute(sql, args or kwgs):            if rowfactory == tuple:                factory = tuple            elif issubclass(rowfactory, dict):                fields = [f[0].lower() for f in curr.description]                factory = lambda x: rowfactory(zip(fields, x))            else:                fields = [f[0].lower() for f in curr.description]                factory = lambda x: rowfactory(**dict(zip(fields, x)))            if batch <= 0:                yield imap(factory, curr.fetchall())            elif batch == 1:                for row in imap(factory, curr):                    yield row            else:                rows = curr.fetchmany(batch)                while rows:                    yield map(factory, rows)                    rows = curr.fetchmany(batch)