Python的MySQL的連接器 - 使用fetchone

Question

我將JSON數據到MySQL數據庫

我解析的JSON，然後將其插入MySQL數據庫使用Python連接器

經過反覆試驗時發現未讀結果，我可以看到錯誤與這段代碼

for steps in result['routes'][0]['legs'][0]['steps']: 
    query = ('SELECT leg_no FROM leg_data WHERE travel_mode = %s AND Orig_lat = %s AND Orig_lng = %s AND Dest_lat = %s AND Dest_lng = %s AND time_stamp = %s') 
    if steps['travel_mode'] == "pub_tran": 
     travel_mode = steps['travel_mode'] 
     Orig_lat = steps['var_1']['dep']['lat'] 
     Orig_lng = steps['var_1']['dep']['lng'] 
     Dest_lat = steps['var_1']['arr']['lat'] 
     Dest_lng = steps['var_1']['arr']['lng'] 
     time_stamp = leg['_sent_time_stamp'] 
    if steps['travel_mode'] =="a_pied": 
     query = ('SELECT leg_no FROM leg_data WHERE travel_mode = %s AND Orig_lat = %s AND Orig_lng = %s AND Dest_lat = %s AND Dest_lng = %s AND time_stamp = %s') 
     travel_mode = steps['travel_mode'] 
     Orig_lat = steps['var_2']['lat'] 
     Orig_lng = steps['var_2']['lng'] 
     Dest_lat = steps['var_2']['lat'] 
     Dest_lng = steps['var_2']['lng'] 
     time_stamp = leg['_sent_time_stamp'] 
    cursor.execute(query,(travel_mode, Orig_lat, Orig_lng, Dest_lat, Dest_lng, time_stamp)) 
    leg_no = cursor.fetchone()[0] 
    print(leg_no) 

我已經插入更高層次的細節，我現在搜索數據庫將與其父這一水平的信息相關聯關聯。找到這個唯一值的唯一方法是使用time_stamp通過原點和目標座標進行搜索。我相信邏輯是正確的，通過在本節之後立即打印leg_no，我可以看到在第一次檢查時出現的值是正確的

但是，當添加到代碼的其餘部分時，會導致後續部分更多的數據使用光標失敗，這個錯誤被插入 -

raise errors.InternalError("Unread result found.") 
mysql.connector.errors.InternalError: Unread result found. 

這個問題似乎類似於MySQL Unread Result with Python

是查詢太複雜，需要分割或有其他問題？

如果查詢確實太複雜了，誰能告訴如何最好地分割這個？

編輯按@戈德的幫助下，我已經企圖把未讀的結果

cursor.execute(query,(leg_travel_mode, leg_Orig_lat, leg_Orig_lng, leg_Dest_lat, leg_Dest_lng)) 
      leg_no = cursor.fetchone()[0] 
      try: 
       cursor.fetchall() 
      except mysql.connector.errors.InterfaceError as ie: 
       if ie.msg == 'No result set to fetch from.': 
        pass 
       else: 
        raise 
      cursor.execute(query,(leg_travel_mode, leg_Orig_lat, leg_Orig_lng, leg_Dest_lat, leg_Dest_lng, time_stamp)) 

但是，我仍然得到

raise errors.InternalError("Unread result found.") 
mysql.connector.errors.InternalError: Unread result found. 
[Finished in 3.3s with exit code 1] 

劃痕頭

EDIT 2 - 當我打印ie.msg，我得到 -

No result set to fetch from 

Answer 1

所有需要的是將緩衝設置爲true！

cursor = cnx.cursor(buffered=True) 

Answer 2

我能夠重新創建您的問題。 MySQL連接器/ Python顯然不喜歡它，如果你檢索多行並且在關閉遊標或使用它來檢索其他東西之前沒有抓取它們。例如

import mysql.connector 
cnxn = mysql.connector.connect(
    host='127.0.0.1', 
     user='root', 
     password='whatever', 
     database='mydb') 
crsr = cnxn.cursor() 
crsr.execute("DROP TABLE IF EXISTS pytest") 
crsr.execute(""" 
CREATE TABLE pytest (
    id INT(11) NOT NULL AUTO_INCREMENT, 
    firstname VARCHAR(20), 
    PRIMARY KEY (id) 
    ) 
""") 
crsr.execute("INSERT INTO pytest (firstname) VALUES ('Gord')") 
crsr.execute("INSERT INTO pytest (firstname) VALUES ('Anne')") 
cnxn.commit() 
crsr.execute("SELECT firstname FROM pytest") 
fname = crsr.fetchone()[0] 
print(fname) 
crsr.execute("SELECT firstname FROM pytest") # InternalError: Unread result found. 

如果你只希望（或者關心）一行，那麼你可以把LIMIT您的查詢

crsr.execute("SELECT firstname FROM pytest LIMIT 0, 1") 
fname = crsr.fetchone()[0] 
print(fname) 
crsr.execute("SELECT firstname FROM pytest") # OK now 

，或者您可以使用fetchall()擺脫任何未讀的結果在完成對您檢索的行的處理之後。

crsr.execute("SELECT firstname FROM pytest") 
fname = crsr.fetchone()[0] 
print(fname) 
try: 
    crsr.fetchall() # fetch (and discard) remaining rows 
except mysql.connector.errors.InterfaceError as ie: 
    if ie.msg == 'No result set to fetch from.': 
     # no problem, we were just at the end of the result set 
     pass 
    else: 
     raise 
crsr.execute("SELECT firstname FROM pytest") # OK now