Wie zwei Listen vergleichen und sie in Python / MySQL fusionieren?

Question

Ich möchte Daten verschmelzen. Im Folgenden sind meine MySQL-Tabellen. Ich mag Python verwenden, wenn eine Liste der beiden Listen (eines mit Betrogene = ‚x‘ und andere mit null Betrogenen) zu durchqueren.

Dies ist ein Beispieldaten. Die tatsächlichen Daten sind humongous.

Zum Beispiel:

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

Aus der obigen Beispieltabelle, die gewünschte Ausgabe ist:

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

Was ich habe, so weit:

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()

Danke Jungs!

Answer 1

OK, lassen Sie uns have some fun ...

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]}