在SQL中仅为元素选择n行

问题描述

我有一个表，其中每个table2_id都有很多列，我只希望ID最多的5行

id | table_2_id | name
----------------------
1  | 1          |A
2  | 1          |B
3  | 1          |C
4  | 1          |D
5  | 1          |E
6  | 1          |F 
7  | 1          |F 
8  | 2          |G
9  | 3          |H 
10 | 3          |I

table_2_id中有7个元素中有1个，我想有5个

所以我想拥有

id | table_2_id | name
----------------------
3  | 1          |C
4  | 1          |D
5  | 1          |E
6  | 1          |F 
7  | 1          |F 
8  | 2          |G
9  | 3          |H 
10 | 3          |I

解决方法

您可以使用import json,httplib connection = httplib.HTTPSConnection('parseapi.back4app.com',443) connection.connect() connection.request('POST','/files/a.mp3',open('a.mp3','rb').read(),{ "X-Parse-Application-Id": "${APPLICATION_ID}","X-Parse-REST-API-Key": "${REST_API_KEY}","Content-Type": "audio/mpeg" }) result = json.loads(connection.getresponse().read())

connection.request('POST','/classes/sounds',json.dumps({
       "displayText": "test","audio": {
         "name": result["name"],"url:": result["url"],"__type": "File"
       }
     }),"Content-Type": "application/json"
     })
connection.getresponse().read()