Question

我正在为Python创建一个Mysql Wrapper，主要是为了学习语言的来龙去脉等。尽管我偶然发现了一个找不到解决方案的问题。

运行脚本时，尽管我的数据库没有更新，但没有引发异常。我玩过DB游标，例如关闭它们，在函数中创建新游标等。但是结果仍然相同。

aka：cursor.rowcount -1

连接到数据库：

class magicDB:
    myDB = None
    DB_Cursor = None

    def __init__(self,host, user, passwd, DB=None):
        global myDB
        self.host = host
        self.user = user
        self.DB = DB

        if self.DB is None:
            myDB = mysql.connector.connect(
                host= host,
                user= user,
                passwd= passwd)
            #DB_Cursor = myDB.cursor()
        else:
            myDB = mysql.connector.connect(
                host= host,
                user= user,
                passwd= passwd,
                database=DB)
            #DB_Cursor = myDB.cursor()
    def insert(self,table_name, params):


            fields = ''
            values = ''
            placeholders = ''

            query = '"INSERT INTO {} '. format(table_name)
            for key in params:
                fields = fields + str(key) + ', '
                values = values + str(params[key]) + ', '
                placeholders = placeholders + str('%s, ')

            fields = fields[:-2]
            values = values[:-2]
            placeholders = placeholders[:-2]
            query = query + '(' + fields + ')' + ' VALUES ' + '(' + placeholders + ')"'
            print(query)
            try:
                Cursor = myDB.cursor()
                Cursor.execute(operation=query, params=values, multi=True)
                myDB.commit()
                print(Cursor.rowcount, ' Record inserted')
            except mysql.connector.Error as error:
                print (error)
            finally:    
                Cursor.close()

这是调用函数的主要模块：

from db_magic import magicDB

conn = magicDB(host='localhost', user='***', passwd='****', DB='testing')
print(conn)


# print(conn.DB_create('testing2'))


conn.insert(table_name= 'users', params={
    'user_name': 'John Doe',
    'email' : 'test@123.com',
    'password': 'test'

} )
print(conn.Close_conn())

我试图理解我在这里做错了什么，因为没有抛出异常。

解决方案：

将值更改为列表而不是字符串。

def insert(self,table_name, params):      
        fields = ''
        values = [] # changed to List instead of String
        placeholders = ''

        query = 'INSERT INTO {} '. format(table_name)
        for key in params:
            fields = fields + str(key) + ', '
            values.append(params[key])
            placeholders = placeholders + str('%s, ')

        fields = fields[:-2]
        placeholders = placeholders[:-2]
        query = query + '(' + fields + ')' + ' VALUES ' + '(' + placeholders + ')'
        print(query)
        print(values)
        try:
            Cursor = myDB.cursor()
            Cursor.execute(operation=query, params=values, multi=False)
            myDB.commit()
            print(Cursor.rowcount, ' Record inserted')
        except mysql.connector.Error as error:
            print(error)
        except:
            print ('Some errors')
        finally:    
            Cursor.close()

Answer 1

Values变量用作字符串，MYSQL-连接器不会迭代该字符串。为了解决这个问题，我将“值变量”更改为列表：

def insert(self,table_name, params):      
        fields = ''
        values = [] # changed to List instead of String
        placeholders = ''

        query = 'INSERT INTO {} '. format(table_name)
        for key in params:
            fields = fields + str(key) + ', '
            values.append(params[key])
            placeholders = placeholders + str('%s, ')

        fields = fields[:-2]
        placeholders = placeholders[:-2]
        query = query + '(' + fields + ')' + ' VALUES ' + '(' + placeholders + ')'
        print(query)
        print(values)
        try:
            Cursor = myDB.cursor()
            Cursor.execute(operation=query, params=values, multi=False)
            myDB.commit()
            print(Cursor.rowcount, ' Record inserted')
        except mysql.connector.Error as error:
            print(error)
        except:
            print ('Some errors')
        finally:    
            Cursor.close()

INSERT函数不会引发错误，仍然不会更新数据库表

1 个答案: