Comment comparer 2 listes et les fusionner en Python/MySQL?

Question

Je souhaite fusionner des données. Voici mes tables MySQL. Je veux utiliser Python pour traverser une liste des deux Listes (une avec dupe = 'x' et l'autre avec des dupes nulles).

Ceci est un exemple de données. Les données réelles sont gigantesques.

Par exemple:

a b c d e f key dupe 
-------------------- 
1 d c f k l 1 x 
2 g h j 1  
3 i h u u 2 
4 u r  t 2 x 

A partir de la table d'exemple ci-dessus, la sortie désirée est:

a b c d e f key dupe 
-------------------- 
2 g c h k j 1 
3 i r h u u 2 

Ce que j'ai jusqu'à présent:

import string, os, sys 
import MySQLdb 
from EncryptedFile import EncryptedFile 

enc = EncryptedFile(os.getenv("HOME") + '/.py-encrypted-file') 
user = enc.getValue("user") 
pw = enc.getValue("pw") 

db = MySQLdb.connect(host="127.0.0.1", user=user, passwd=pw,db=user) 

cursor = db.cursor() 
cursor2 = db.cursor() 

cursor.execute("select * from delThisTable where dupe is null") 
cursor2.execute("select * from delThisTable where dupe is not null") 
result = cursor.fetchall() 
result2 = cursor2.fetchall() 

for each record 
    for each field 
     perform the comparison and perform the necessary updates 

      ### How do I compare the record with same key value and update the original row null field value with the non-null value from the duplicate? Please fill this void... 


cursor.close() 
cursor2.close() 
db.close() 

Merci les gars!

Answer 1

OK, nous allons avoir du plaisir ...

mysql> create table so (a int, b char, c char, d char, e char, f char, `key` int, dupe char); 
Query OK, 0 rows affected (0.05 sec) 

mysql> insert into so values (1, 'd', 'c', 'f', 'k', 'l', 1, 'x'), (2, 'g', null, 'h', null, 'j', 1, null), (3, 'i', null, 'h', 'u', 'u', 2, null), (4, 'u', 'r', null, null, 't', 2, 'x'); 
Query OK, 4 rows affected (0.00 sec) 
Records: 4 Duplicates: 0 Warnings: 0 

mysql> select * from so order by a; 
+------+------+------+------+------+------+------+------+ 
| a | b | c | d | e | f | key | dupe | 
+------+------+------+------+------+------+------+------+ 
| 1 | d | c | f | k | l | 1 | x | 
| 2 | g | NULL | h | NULL | j | 1 | NULL | 
| 3 | i | NULL | h | u | u | 2 | NULL | 
| 4 | u | r | NULL | NULL | t | 2 | x | 
+------+------+------+------+------+------+------+------+ 
4 rows in set (0.00 sec) 

---

Python 2.6.5 (r265:79063, Mar 26 2010, 22:43:05) 
[GCC 4.2.1 (Apple Inc. build 5646) (dot 1)] on darwin 
Type "help", "copyright", "credits" or "license" for more information. 
>>> import MySQLdb 
>>> db = MySQLdb.connect(host="127.0.0.1", db="test") 
>>> c = db.cursor() 
>>> c.execute("SELECT a, b, c, d, e, f, `key`, dupe FROM so") 
4L 
>>> rows = c.fetchall() 
>>> rows 
((1L, 'd', 'c', 'f', 'k', 'l', 1L, 'x'), (4L, 'u', 'r', None, None, 't', 2L, 'x'), (2L, 'g', None, 'h', None, 'j', 1L, None), (3L, 'i', None, 'h', 'u', 'u', 2L, None)) 
>>> data = dict() 
>>> for row in rows: 
... key, isDupe = row[-2], row[-1] 
... if key not in data: 
... data[key] = list(row[:-1]) 
... else: 
... for i in range(len(row)-1): 
... if data[key][i] is None or (not isDupe and row[i] is not None): 
...  data[key][i] = row[i] 
... 
>>> data 
{1L: [2L, 'g', 'c', 'h', 'k', 'j', 1L], 2L: [3L, 'i', 'r', 'h', 'u', 'u', 2L]}