将 CSV 数据插入 AWS RDS MySQL DB 时出现错误消息 1054“'字段列表'中的未知列。请告诉我如何解决此错误

Question

This is the AWS Lambda function lambda_function.py code in which I am working on to read the CSV data from AWS S3 bucket and to insert it into AWS RDS MySQL database.

import json
import boto3
import sys
import logging
import rds_config
import pymysql
import csv

s3_client = boto3.client("s3")

#rds settings
rds_host  = "myrdsdatabase-xxxxx-amazonaws.com"
name = rds_config.db_username
password = rds_config.db_password
db_name = rds_config.db_name

logger = logging.getLogger()
logger.setLevel(logging.INFO)

try:
    conn = pymysql.connect(rds_host, user=name, passwd=password, db=db_name, connect_timeout=5)
except pymysql.MySQLError as e:
    logger.error("ERROR: Unexpected error: Could not connect to MySQL instance.")
    logger.error(e)
    sys.exit()

logger.info("SUCCESS: Connection to RDS MySQL instance succeeded")

def lambda_handler(event, context):
    
    bucket_name = event['Records'][0]['s3']['bucket']['name']
    s3_file_name = event['Records'][0]['s3']['object']['key']
    csv_file = s3_client.get_object(Bucket=bucket_name,Key=s3_file_name)
    record_list = csv_file['Body'].read().decode("utf-8").split('\n')
    print('RAW CSV Data:')
    print(record_list)
    csv_reader = csv.reader(record_list, delimiter=',', quotechar='"')
    colheader, *rows = csv_reader
    print('Data to be inserted into RDS MySQL:')
    for r in rows:
        empID = r[0]
        empName = r[1]
        print(empID+' '+empName)    
    
    """
    This function fetches content from MySQL RDS instance
    """
    result = []
    
    with conn.cursor() as cur:
        #cur.execute("create table Employee ( EmpID int NOT NULL, EmpName varchar(255) NOT NULL, PRIMARY KEY (EmpID))")
        #cur.execute("Drop table Employee")
        #cur.execute("Delete from Employee")
        #cur.execute('insert into Employee (EmpID, EmpName) values(0,"Test")')
        #cur.execute("select * from Employee")
        #conn.commit()
        #cur.close()
        
        for r in rows:
            empID = r[0]
            empName = r[1]
            cur.execute('insert into Employee (EmpID, EmpName) values('+empID+','+empName+')')
            cur.execute("select * from Employee")
            conn.commit()
            cur.close()
            
        for row in cur:
            result.append(list(row))
        print ("Data from AWS RDS MySQL...")
        print (result)

Output：-

Response:
{
  "errorMessage": "(1054, \"Unknown column 'Tom' in 'field list'\")",
  "errorType": "InternalError",
  "stackTrace": [
    "  File \"/var/task/lambda_function.py\", line 62, in lambda_handler\n    cur.execute('insert into Employee (EmpID, EmpName) values('+empID+','+empName+')')\n",
    "  File \"/var/task/pymysql/cursors.py\", line 165, in execute\n    result = self._query(query)\n",
    "  File \"/var/task/pymysql/cursors.py\", line 321, in _query\n    conn.query(q)\n",
    "  File \"/var/task/pymysql/connections.py\", line 860, in query\n    self._affected_rows = self._read_query_result(unbuffered=unbuffered)\n",
    "  File \"/var/task/pymysql/connections.py\", line 1061, in _read_query_result\n    result.read()\n",
    "  File \"/var/task/pymysql/connections.py\", line 1349, in read\n    first_packet = self.connection._read_packet()\n",
    "  File \"/var/task/pymysql/connections.py\", line 1018, in _read_packet\n    packet.check_error()\n",
    "  File \"/var/task/pymysql/connections.py\", line 384, in check_error\n    err.raise_mysql_exception(self._data)\n",
    "  File \"/var/task/pymysql/err.py\", line 107, in raise_mysql_exception\n    raise errorclass(errno, errval)\n"
  ]
}

Request ID:
"6b8f70cd-dc9a-458c-9024-c4ecdb9a913e"

Function logs:
START RequestId: 6b8f70cd-dc9a-458c-9024-c4ecdb9a913e Version: $LATEST
RAW CSV Data:
['EmpID,EmpName\r', '1,Tom\r', '2,Jack\r', '3,Ross\r', '4,William']
Data to be inserted into RDS MySQL:
1 Tom
2 Jack
3 Ross
4 William
[ERROR] InternalError: (1054, "Unknown column 'Tom' in 'field list'")
Traceback (most recent call last):
  File "/var/task/lambda_function.py", line 62, in lambda_handler
    cur.execute('insert into Employee (EmpID, EmpName) values('+empID+','+empName+')')
  File "/var/task/pymysql/cursors.py", line 165, in execute
    result = self._query(query)
  File "/var/task/pymysql/cursors.py", line 321, in _query
    conn.query(q)
  File "/var/task/pymysql/connections.py", line 860, in query
    self._affected_rows = self._read_query_result(unbuffered=unbuffered)
  File "/var/task/pymysql/connections.py", line 1061, in _read_query_result
    result.read()
  File "/var/task/pymysql/connections.py", line 1349, in read
    first_packet = self.connection._read_packet()
  File "/var/task/pymysql/connections.py", line 1018, in _read_packet
    packet.check_error()
  File "/var/task/pymysql/connections.py", line 384, in check_error
    err.raise_mysql_exception(self._data)
  File "/var/task/pymysql/err.py", line 107, in raise_mysql_exception
    raise errorclass(errno, errval)
END RequestId: 6b8f70cd-dc9a-458c-9024-c4ecdb9a913e
REPORT RequestId: 6b8f70cd-dc9a-458c-9024-c4ecdb9a913e  Duration: 223.12 ms Billed Duration: 300 ms Memory Size: 128 MB Max Memory Used: 80 MB  Init Duration: 488.20 ms    

注意：- 我可以将硬代码值插入 RDS MySQL 数据库，但是当尝试插入 CSV 文件值时，只会收到此错误。

如果需要任何有助于调试此错误并找到根本原因的进一步信息，请告诉我。

提前致谢！！！

Answer 1

cur.execute 调用中存在语法问题。 现在更改语法后，我可以成功地将 CSV 数据插入 RDS MySQL 数据库。

更正：

cur.execute("insert into Employee (EmpID, EmpName) values(%s,%s)", (empID,empName))

Answer 2

我相信这个问题源于这一行：

cur.execute('insert into Employee (EmpID, EmpName) values('+empID+','+empName+')')

员工姓名是一个字符串，但在生成的 SQL 语句中没有被引用。 目前的方式将导致 SQL 语句，如：

INSERT INTO Employee (EmpID, EmpName) VALUES (1, Tom);

你想要的是：

INSERT INTO Employee (EmpID, EmpName) VALUES (1, 'Tom'); （注意汤姆周围的引号）

您可以将这些引号添加到 cur.execute 调用中：

cur.execute('insert into Employee (EmpID, EmpName) values (' + empID + ', "' + empName + '")')

或者使用这里描述的语法： How to use variables in SQL statement in Python?