最近在幫別人做一個小型的網站(包括web前端),在使用的過程中,出現了以下的bug:
in Execute_SQL cursor = conn.cursor() ,in cursor raise errors.OperationlError (MySQL Connection not available.)
出現這個bug後,只要涉及到數據庫方面的處理都會出錯。經過一番煞費苦心的查找解決方法時,在這篇文章中找到答案:http://bugs.mysql.com/bug.php?id=67649,解釋如下:
Description:
If you open an unbuffered cursor and you do not read the WHOLE result set before closing the cursor, the next query will fail with
File "/usr/lib/python3.2/site-packages/mysql/connector/connection.py", line 1075, in cursor
raise errors.OperationalError("MySQL Connection not available.")
mysql.connector.errors.OperationalError: MySQL Connection not available.
and all subsequent database calls will fail too.
上文說如果你打開了一個cursor,但是沒有把裏面的結果集都read一遍就把它close掉了,後續訪問數據庫都會失敗。
解決方法:
1.在調用cursor.close(),丟棄所有未讀的結果
我的解決方法,原代碼如下:
def Execute_SQL ( command , var = None , search = True ) :
cursor = conn.cursor ( )
if var is None :
cursor.execute ( command )
else :
cursor.execute ( command , var )
if search :
values = cursor.fetchall ( )
else :
values = cursor.rowcount
conn.commit ( )
cursor.close ( )
return values
改後的代碼:
def Execute_SQL ( command , var = None , search = True ) :
cursor = conn.cursor ( )
if var is None :
cursor.execute ( command )
else :
cursor.execute ( command , var )
if search :
values = cursor.fetchall ( )
else :
# values = cursor.rowcount
values = cursor.fetchone();
while values:
print (values);
values = cursor.fetchone();
conn.commit ( )
cursor.close ( )
return values