如何比較2個列表並將它們合併到Python/MySQL中？

Question

我想合併數據。以下是我的MySQL表。我想用Python遍歷這兩個列表（其中一個用dupe ='x'，另一個用null dupes）。

這是示例數據。實際數據是巨大的。

例如：

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 

從上面的示例表，所需的輸出是：

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

我到目前爲止有：

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() 

謝謝你們！

Answer 1

OK，讓我們有一些有趣的...

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]}