请教关于cursor的写法

doublelook

有一句mysql的语句像这样的：select * from purchase where p_date like '2009-05%';
在下面的函数中如何写cursor

def my_sql(year, month):
    from django.db import connection
    YM = year + "-" + month
    cursor = connection.cursor()
    cursor.execute('select * from purchase where p_date like %s"%" ', [YM])
    pur_set = cursor.fetchall()
    return pur_set

上面的：cursor.execute('select * from purchase where p_date like %s"%" ', [YM]) 运行时出错，
错误提示是：TypeError:not enough arguments for format string.
请问，这个要怎么写

xiaoyu9805119

cursor.execute('select * from purchase where p_date like "%s%%" ', [YM])