create_table_query = cursor.execute(create_table_query) 提供一个创建相同表结构的create_table_query = 语句

要创建与已给示例相同的表结构，你可以构造一个SQL `CREATE TABLE`语句，然后通过`cursor.execute()`执行它。假设你想创建一个名为`employees`的新表，其结构与第一个例子相似：

create_table_query = """
CREATE TABLE employees (
    id INT AUTO_INCREMENT PRIMARY KEY,
    first_name VARCHAR(30),
    last_name VARCHAR(30)
)
"""

如果你想要创建名为`news`的表，就像第二个例子那样，可以这样做：

create_table_query = """
CREATE TABLE news (
    id INTEGER PRIMARY KEY,
    title TEXT,
    content TEXT,
    published_date DATE
)
"""

然后使用`cursor.execute(create_table_query)`来执行这个创建操作。

相关问题

import pandas as pd import pymysql # 连接到数据库 conn = pymysql.connect(host='localhost', user='user', password='password', database='database') # 获取所有表格的名称 cursor = conn.cursor() cursor.execute("SHOW TABLES") tables = cursor.fetchall() # 遍历所有表格 for table in tables: table_name = table[0] table_name_quoted = '' + table_name + '' # 检查是否存在名为'a'的列，如果不存在则添加'a'和'b'列 cursor.execute("SHOW COLUMNS FROM " + table_name_quoted + " LIKE 'a'") a_column = cursor.fetchone() if a_column is None: cursor.execute("ALTER TABLE " + table_name_quoted + " ADD COLUMN a DECIMAL(10,2)") cursor.execute("ALTER TABLE " + table_name_quoted + " ADD COLUMN b DECIMAL(10,2)") conn.commit() # 查询net_mf_amount列的数据 query = "SELECT trade_date, net_mf_amount FROM " + table_name_quoted + " ORDER BY trade_date DESC" df = pd.read_sql_query(query, conn) # 计算a和b列 a_column = [] b_column = [] for i in range(len(df)): if i == 0: a_column.append(None) b_column.append(None) else: if pd.notnull(df.iloc[i]['net_mf_amount']) and pd.notnull(df.iloc[i-1]['net_mf_amount']): if i-2 >= 0: if pd.notnull(df.iloc[i-2]['net_mf_amount']): a = df.iloc[i]['net_mf_amount'] - df.iloc[i-1]['net_mf_amount'] b = df.iloc[i]['net_mf_amount'] - df.iloc[i-2]['net_mf_amount'] a_column.append(a) b_column.append(b) else: j = i-3 while j >= 0: if pd.notnull(df.iloc[j]['net_mf_amount']): a = df.iloc[i]['net_mf_amount'] - df.iloc[i-1]['net_mf_amount'] b = df.iloc[i]['net_mf_amount'] - df.iloc[j]['net_mf_amount'] a_column.append(a) b_column.append(b) break j -= 1 else: a = df.iloc[i]['net_mf_amount'] - df.iloc[i-1]['net_mf_amount'] b = None a_column.append(a) b_column.append(b) else: a_column.append(None) b_column.append(None) # 将结果保存到数据库 for i in range(len(df)): cursor.execute("UPDATE " + table_name_quoted + " SET a=%s, b=%s WHERE trade_date=%s", (a_column[i], b_column[i], df.iloc[i]['trade_date'])) conn.commit() # 关闭连接 cursor.close() conn.close() 报错/Users/ljy/stock/daily_analyse.py:65: UserWarning: pandas only supports SQLAlchemy connectable (engine/connection) or database string URI or sqlite3 DBAPI2 connection. Other DBAPI2 objects are not tested. Please consider using SQLAlchemy. df = pd.read_sql_query(query, conn)

这段代码的报错和之前的一样，是因为使用的连接对象 conn 不是 SQLAlchemy 连接对象或者 SQLite3 的 DBAPI2 连接对象。你可以将该连接对象转换为 SQLAlchemy 连接对象或者使用数据库字符串 URI 来连接数据库。将连接数据库的代码修改如下：

import pandas as pd
from sqlalchemy import create_engine

# 连接到数据库
engine = create_engine('mysql+pymysql://user:password@localhost/database')

# 获取所有表格的名称
with engine.connect() as conn, conn.begin():
    tables = conn.execute("SHOW TABLES").fetchall()

# 遍历所有表格
for table in tables:
    table_name = table[0]
    table_name_quoted = '`' + table_name + '`'

    # 检查是否存在名为'a'的列，如果不存在则添加'a'和'b'列
    with engine.connect() as conn, conn.begin():
        a_column = conn.execute("SHOW COLUMNS FROM " + table_name_quoted + " LIKE 'a'").fetchone()
        if a_column is None:
            conn.execute("ALTER TABLE " + table_name_quoted + " ADD COLUMN a DECIMAL(10,2)")
            conn.execute("ALTER TABLE " + table_name_quoted + " ADD COLUMN b DECIMAL(10,2)")

    # 查询net_mf_amount列的数据
    query = "SELECT trade_date, net_mf_amount FROM " + table_name_quoted + " ORDER BY trade_date DESC"
    df = pd.read_sql_query(query, engine)

    # 计算a和b列
    a_column = []
    b_column = []
    for i in range(len(df)):
        if i == 0:
            a_column.append(None)
            b_column.append(None)
        else:
            if pd.notnull(df.iloc[i]['net_mf_amount']) and pd.notnull(df.iloc[i-1]['net_mf_amount']):
                if i-2 >= 0:
                    if pd.notnull(df.iloc[i-2]['net_mf_amount']):
                        a = df.iloc[i]['net_mf_amount'] - df.iloc[i-1]['net_mf_amount']
                        b = df.iloc[i]['net_mf_amount'] - df.iloc[i-2]['net_mf_amount']
                        a_column.append(a)
                        b_column.append(b)
                    else:
                        j = i-3
                        while j >= 0:
                            if pd.notnull(df.iloc[j]['net_mf_amount']):
                                a = df.iloc[i]['net_mf_amount'] - df.iloc[i-1]['net_mf_amount']
                                b = df.iloc[i]['net_mf_amount'] - df.iloc[j]['net_mf_amount']
                                a_column.append(a)
                                b_column.append(b)
                                break
                            j -= 1
                else:
                    a = df.iloc[i]['net_mf_amount'] - df.iloc[i-1]['net_mf_amount']
                    b = None
                    a_column.append(a)
                    b_column.append(b)
            else:
                a_column.append(None)
                b_column.append(None)

    # 将结果保存到数据库
    with engine.connect() as conn, conn.begin():
        for i in range(len(df)):
            conn.execute("UPDATE " + table_name_quoted + " SET a=%s, b=%s WHERE trade_date=%s", (a_column[i], b_column[i], df.iloc[i]['trade_date']))

# 关闭连接
engine.dispose()

注意：上述代码中的 user, password 和 database 分别对应的是你自己的用户名、密码和数据库名，需要进行修改。

在python里mysql重构这段代码import sqlite3 class TeacherDatabase: def __init__(self): # 连接数据库 self.conn = sqlite3.connect('teacher.db') # 获取游标 self.cursor = self.conn.cursor() # 创建表 self.cursor.execute(''' CREATE TABLE IF NOT EXISTS scetc_teacher ( teacher_id VARCHAR(32) PRIMARY KEY, teacher_name VARCHAR(16), teacher_profession VARCHAR(64), teacher_tech VARCHAR(64), teacher_post VARCHAR(32) ); ''') self.conn.commit() def add_teacher(self): # 从控制台输入教师信息 teacher_id = input('请输入工号：') teacher_name = input('请输入姓名：') teacher_profession = input('请输入从事专业：') teacher_tech = input('请输入职称：') teacher_post = input('请输入职位：') # 判断工号是否已存在 self.cursor.execute('SELECT * FROM scetc_teacher WHERE teacher_id=?', (teacher_id,)) if self.cursor.fetchone(): print('该工号已存在，请重新输入！') return # 将教师信息写入数据库 self.cursor.execute('INSERT INTO scetc_teacher VALUES (?, ?, ?, ?, ?)', (teacher_id, teacher_name, teacher_profession, teacher_tech, teacher_post)) self.conn.commit() print('教师信息添加成功！') def query_teacher(self): # 查询所有教师信息并在控制台打印显示 self.cursor.execute('SELECT * FROM scetc_teacher') teachers = self.cursor.fetchall() if not teachers: print('暂无教师信息！') else: for teacher in teachers: print('工号：%s，姓名：%s，从事专业：%s，职称：%s，职位：%s' % teacher) def __del__(self): # 关闭连接 self.cursor.close() self.conn.close() if __name__ == '__main__': db = TeacherDatabase() db.add_teacher() db.query_teacher()

可以使用 Python 中的 PyMySQL 模块来重构这段代码，如下所示：

import pymysql

class TeacherDatabase:
    def __init__(self):
        # 连接数据库
        self.conn = pymysql.connect(
            host='localhost',
            user='username',
            password='password',
            db='teacher'
        )
        # 获取游标
        self.cursor = self.conn.cursor()
        # 创建表
        self.cursor.execute('''
            CREATE TABLE IF NOT EXISTS scetc_teacher (
                teacher_id VARCHAR(32) PRIMARY KEY,
                teacher_name VARCHAR(16),
                teacher_profession VARCHAR(64),
                teacher_tech VARCHAR(64),
                teacher_post VARCHAR(32)
            );
        ''')
        self.conn.commit()

    def add_teacher(self):
        # 从控制台输入教师信息
        teacher_id = input('请输入工号：')
        teacher_name = input('请输入姓名：')
        teacher_profession = input('请输入从事专业：')
        teacher_tech = input('请输入职称：')
        teacher_post = input('请输入职位：')

        # 判断工号是否已存在
        self.cursor.execute('SELECT * FROM scetc_teacher WHERE teacher_id=%s', (teacher_id,))
        if self.cursor.fetchone():
            print('该工号已存在，请重新输入！')
            return

        # 将教师信息写入数据库
        self.cursor.execute('INSERT INTO scetc_teacher VALUES (%s, %s, %s, %s, %s)',
                            (teacher_id, teacher_name, teacher_profession, teacher_tech, teacher_post))
        self.conn.commit()
        print('教师信息添加成功！')

    def query_teacher(self):
        # 查询所有教师信息并在控制台打印显示
        self.cursor.execute('SELECT * FROM scetc_teacher')
        teachers = self.cursor.fetchall()
        if not teachers:
            print('暂无教师信息！')
        else:
            for teacher in teachers:
                print('工号：%s，姓名：%s，从事专业：%s，职称：%s，职位：%s' % teacher)

    def __del__(self):
        # 关闭连接
        self.cursor.close()
        self.conn.close()

if __name__ == '__main__':
    db = TeacherDatabase()
    db.add_teacher()
    db.query_teacher()

这里我们使用了 PyMySQL 来连接 MySQL 数据库，对于表的创建和数据的操作与原来的代码基本相同。只需要修改连接数据库的方式和 SQL 语句中的占位符即可。