MySQL Python插入奇怪？

Question

我不明白爲什麼它不起作用。我創建了幾個數據庫和表格，顯然沒有問題。但我堅持這個從django數據模型創建的表。爲了闡明我所做的，從mysql控制檯創建了新的數據庫和表，並嘗試從python插入並工作。但是，這對我來說很奇怪。

class Experiment(models.Model): 
    user = models.CharField(max_length=25) 
    filetype = models.CharField(max_length=10) 
    createddate= models.DateField() 
    uploaddate = models.DateField() 
    time = models.CharField(max_length=20) 
    size = models.CharField(max_length=20) 
    located= models.CharField(max_length=50) 

這是鑑於在MySQL控制檯

mysql> describe pmass_experiment; 
+-------------+-------------+------+-----+---------+----------------+ 
| Field  | Type  | Null | Key | Default | Extra   | 
+-------------+-------------+------+-----+---------+----------------+ 
| id   | int(11)  | NO | PRI | NULL | auto_increment | 
| user  | varchar(25) | NO |  | NULL |    | 
| filetype | varchar(10) | NO |  | NULL |    | 
| createddate | date  | NO |  | NULL |    | 
| uploaddate | date  | NO |  | NULL |    | 
| time  | varchar(20) | NO |  | NULL |    | 
| size  | varchar(20) | NO |  | NULL |    | 
| located  | varchar(50) | NO |  | NULL |    | 
+-------------+-------------+------+-----+---------+----------------+ 
8 rows in set (0.01 sec) 

以上pmass_experiment表由Django的ORM後蟒蛇manage.py執行syncdb

現在我想插入數據創建通過python MySQLdb進入pmass_experiment

import MySQLdb 
import datetime,time 
import sys 

conn = MySQLdb.connect(
    host="localhost", 
    user="root", 
    passwd="root", 
    db="experiment") 

cursor = conn.cursor() 
user='tchand' 
ftype='mzml' 
size='10MB' 
located='c:\' 
date= datetime.date.today() 
time = str(datetime.datetime.now())[10:19] 

#Insert into database 
sql = """INSERT INTO pmass_experiment (user,filetype,createddate,uploaddate,time,size,located) 
    VALUES (user, ftype, date, date, time, size, located)""" 
try: 
    # Execute the SQL command 
    cursor.execute(sql) 
    # Commit your changes in the database 
    conn.commit() 
except: 
    # Rollback in case there is any error 
    conn.rollback() 
# disconnect from server 
conn.close() 

但是，不幸的是沒有插入。我猜這可能是由於primary_key（id）在表中不自動遞增。

mysql> select * from pmass_experiment; 
Empty set (0.00 sec) 

你能指出我的錯嗎？

感謝

Answer 1

sql = """INSERT INTO pmass_experiment (user,filetype,createddate,uploaddate,time,size,located) 
    VALUES (user, ftype, date, date, time, size, located)""" 

參數多態的SQL，並傳入值作爲第二個參數cursor.execute：

sql = """INSERT INTO pmass_experiment (user,filetype,createddate,uploaddate,time,size,located) 
     VALUES (%s, %s, %s, %s, %s, %s, %s)""" 
try: 
    # Execute the SQL command 
    cursor.execute(sql,(user, ftype, date, date, time, size, located)) 
    # Commit your changes in the database 
    conn.commit() 
except Exception as err: 
    # logger.error(err) 
    # Rollback in case there is any error 
    conn.rollback() 

這是一個好習慣，總是參數化的SQL，因爲這將有助於防止sql injection 。

原來的SQL

INSERT INTO pmass_experiment (user,filetype,createddate,uploaddate,time,size,located) 
    VALUES (user, ftype, date, date, time, size, located) 

似乎是有效的。在mysql殼的實驗表明它插入NULL值行：

mysql> insert into foo (first,last,value) values (first,last,value); 
Query OK, 1 row affected (0.00 sec) 
mysql> select * from foo order by id desc; 
+-----+-------+------+-------+ 
| id | first | last | value | 
+-----+-------+------+-------+ 
| 802 | NULL | NULL | NULL | 
+-----+-------+------+-------+ 
1 row in set (0.00 sec) 

所以我不知道爲什麼你沒有看到提交到數據庫表中的所有行。

儘管如此，原始的sql可能不會做你想要的。