我正在将脚本从另一种语言迁移到Python。我对数据库调用的具体细节进行了淡化......但这就是文件的样子。我故意使一些查询失败，因为我正在测试事务并且它没有回滚（）在强制错误之前执行的查询。我对如何处理Python的事务感到有些困惑，我遵循的例子是this one，它是一个循环，其中有几个查询嵌套在事务中，所以我根据我的理解调整了代码。
#!/usr/bin/python
import MySQLdb
import thread
import os
# Open database connection
# added local_infile=1 to allow the import to work, otherwise you get an error
db = MySQLdb.connect(CONNECTION ARGS...)
# define our function that will be called from our thread
def import_queued_file(conn,distid):
# prepare a cursor object using cursor() method
cursor = conn.cursor()
# total lines imported for all files for a distributor
total_lines_imported = 0
# current lines imported for each file on each iteration
current_lines_imported = 0
# default this to 0, this will have the total lines for our imports on each iteration
previous_lines_imported = 0
# initialize the file exists flag to 0
file_exists = 0
# sql statement to retrieve the file(s) for a specific distributor
sql = """
SELECT
...
FROM ...
WHERE ...
"""
# execute the sql statement
cursor.execute(sql)
# if we have records, execute the code below
if (cursor.rowcount > 0):
# set the records to the files variable
files = cursor.fetchall()
# set a variable to count iterations
# we'll use this to determine if we need to drop the table
cnt = 0
# keep track of the total number of lines imported per distributor (may be multiple files)
lines_imported = 0
# loop the recordset
for col in files:
# increment the cnt variable
cnt += 1
# set file_exists to 0 at the beginning of the iteration
file_exists = 0
# set some variables to be used in our sql load data statement
var1 = col[1]
var2 = col[2]
....
# this is the path of our file that we will be using for MySQL LOAD DATA also
# TODO: REFACTOR SO THAT THE /home/webex/backup/ IS NOT HARD CODED
inventoryfile = "/path/to/file/%s" % (filepath)
# check to see if we have a file
if (os.path.exists(inventoryfile)):
try:
# set file exists to true
file_exists = 1
# if cnt > 1, it means we have more than 1 file for this distributor
# only drop the table if this is the first iteration
if (cnt == 1):
# drop table sql statement
sql = "DROP TABLE IF EXISTS %s" % (temptable)
# execute the sql command
cur = conn.cursor()
cur.execute(sql)
cur.close()
# assign the create table statement to the sql variable
sql = """
CREATE TABLE IF NOT EXISTS
.......
.......
) ENGINE=MyISAM DEFAULT CHARSET=utf8
""" % (temptable)
# execute the sql statement
cur = conn.cursor()
cur.execute(sql)
cur.close()
# query the temptable to see if we have any records
sql = "SELECT COUNT(0) AS total FROM %s" % (temptable)
cur = conn.cursor()
cur.execute(sql)
cur.close()
# get the count of how many records exist in the database
number_of_line_items = cur.fetchall()
previous_lines_imported = number_of_line_items[0][0]
# load data local infile sql statement
sql = """
LOAD DATA LOCAL INFILE ...
"""
# execute the load data infile sql statement
cur = conn.cursor()
cur.execute(sql)
cur.close()
# clean up the table by removing...
# rows that don't have a part_number,
# rows that have part_number's less than 3 characters
sql = """
DELETE FROM ...
""" % (temptable)
# execute the delete query
cur = conn.cursor()
cur.execute(sql)
cur.close()
# query the temptable to see if we have any records after the import
sql = "SELECT COUNT(0) AS total FROM %s" % (temptable)
# execute the count query
cur = conn.cursor()
cur.execute(sql)
cur.close()
# get the count of how many records exist in the database after the import
number_of_line_items = cur.fetchall()
# get the current lines imported
current_lines_imported = number_of_line_items[0][0] - previous_lines_imported
# add the current lines imported to the total lines imported
total_lines_imported += current_lines_imported
# update distributor_file_settings table last_updated_on field
sql = """
UPDATE ...
""" % (file_id,distributor__id)
print sql
# execute the update query
cur = conn.cursor()
cur.execute(sql)
cur.close()
# close cursor
conn.commit()
except:
conn.rollback()
# no records exists for this distributor
else:
print "dist doesn't exist"
cursor.close()
import_queued_file(db,42)
# prepare a cursor object using cursor() method
cursor = db.cursor()
# select distinct file settings
sql = """
SELECT ...
"""
# disconnect from server
db.close()
答案 0 :(得分：1)
一次又一次地检查代码后，问题恰好是表类型。将其更改为INNODB后，它按预期工作。