代码:
import pymysql
connection = pymysql.connect(host="localhost",user="root",password="123456",db="test06",charset='utf8')
cursor = connection.cursor()
sql = "insert into emp(empno,ename) values(%s,%s)"
args=(1234,'marry')
count = cursor.execute(sql,args)
print("count:",count)
connection.commit()
报错:
Traceback (most recent call last):
File "d:\Python\test\.vscode\.vscode\db_test\db91_插入数据.py", line 7, in <module>
count = cursor.execute(sql,args)
File "C:\Users\qianc\AppData\Roaming\Python\Python39\site-packages\pymysql\cursors.py", line 148, in execute
result = self._query(query)
File "C:\Users\qianc\AppData\Roaming\Python\Python39\site-packages\pymysql\cursors.py", line 310, in _query
conn.query(q)
File "C:\Users\qianc\AppData\Roaming\Python\Python39\site-packages\pymysql\connections.py", line 548, in query
self._affected_rows = self._read_query_result(unbuffered=unbuffered)
File "C:\Users\qianc\AppData\Roaming\Python\Python39\site-packages\pymysql\connections.py", line 775, in _read_query_result
result.read()
File "C:\Users\qianc\AppData\Roaming\Python\Python39\site-packages\pymysql\connections.py", line 1156, in read
first_packet = self.connection._read_packet()
File "C:\Users\qianc\AppData\Roaming\Python\Python39\site-packages\pymysql\connections.py", line 725, in _read_packet
packet.raise_for_error()
File "C:\Users\qianc\AppData\Roaming\Python\Python39\site-packages\pymysql\protocol.py", line 221, in raise_for_error
err.raise_mysql_exception(self._data)
File "C:\Users\qianc\AppData\Roaming\Python\Python39\site-packages\pymysql\err.py", line 143, in raise_mysql_exception
raise errorclass(errno, errval)
pymysql.err.IntegrityError: (1062, "Duplicate entry '1234' for key 'emp.PRIMARY'")
请问哪里出错了
s实例化泛型类Node时都没有写<E>，这样它默认的类型就是Object，会不会遇到转型报错？是否写为Node<E> node = this.head;更加规范？
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