传递python列表oracle where子句cx\U oracle

试图将Python列表传递给Oracle WHERE子句，我感到很沮丧。我正在使用cx_Oracle，以下是我的代码：

# -*- coding: utf-8 -*-
from __future__ import unicode_literals
import cx_Oracle

con = cx_Oracle.connect(str('user/passwordr@server/orcl'))
cursor = con.cursor()
ids = [19 , 87 , 84]
cursor.execute(str("select  employee_id , first_name , last_name from employees  where employee_id in ('"+ids+"')" ))
people = cursor.fetchall()
print people

'''The following code works for me , but the problem is the string formater placeholer is not gonna be static is dynamic.'''
params = (198 , 199)
cursor.execute(str("select  employee_id , first_name , last_name from employees  where employee_id in ('%s' , '%s')" %(params)))

'''Also it would be valid if i can create dynamically the string formater placeholder depending on "length of something".
Sorry if this question was answered i spend hours searching the solution , but i do not found it.'''

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经过几个小时的努力，我终于找到了解决办法。代码如下：

# -*- coding: utf-8 -*-
#from __future__ import unicode_literals
import cx_Oracle
con = cx_Oracle.connect(str('user/pass@server/orcl'))

cursor = con.cursor()

cursor.execute(str('select employee_id from employees where rownum < 3 '))

desc = [d[0] for d in cursor.description]
resutl = [dict(zip(desc,line)) for line in cursor]

ids = []
for i in range(len(resutl)):
    ids.append(resutl[i]['EMPLOYEE_ID'])

placeholders = ','.join(":x%d" % i for i,_ in enumerate(ids)) 

sql = """SELECT job_id
         FROM job_history
         WHERE employee_id IN (%s)""" % placeholders 

cursor.execute(sql,ids ) 
rs =  cursor.fetchall() 

print rs