使用pymysql写一个实现数据增删改查的数据库接口

好的，以下是一个使用pymysql实现数据增删改查的数据库接口的示例代码：

import pymysql

class Database:
    def __init__(self):
        self.conn = pymysql.connect(
            host='localhost',
            user='root',
            password='password',
            db='test_db',
            charset='utf8mb4',
            cursorclass=pymysql.cursors.DictCursor
        )
        self.cursor = self.conn.cursor()

    def __del__(self):
        self.conn.close()

    def execute_query(self, query, params=None):
        try:
            self.cursor.execute(query, params)
            self.conn.commit()
            return self.cursor.fetchall()
        except Exception as e:
            self.conn.rollback()
            raise e

    def insert(self, table_name, data):
        columns = ', '.join(data.keys())
        values = ', '.join(['%s']*len(data))
        query = f"INSERT INTO {table_name} ({columns}) VALUES ({values})"
        self.execute_query(query, tuple(data.values()))

    def update(self, table_name, data, condition):
        set_values = ', '.join([f"{k}=%s" for k in data.keys()])
        query = f"UPDATE {table_name} SET {set_values} WHERE {condition}"
        self.execute_query(query, tuple(data.values()))

    def delete(self, table_name, condition):
        query = f"DELETE FROM {table_name} WHERE {condition}"
        self.execute_query(query)

    def select(self, table_name, columns=None, condition=None):
        selected_columns = '*' if columns is None else ', '.join(columns)
        query = f"SELECT {selected_columns} FROM {table_name}"
        if condition is not None:
            query += f" WHERE {condition}"
        return self.execute_query(query)

使用示例：

db = Database()

# 插入数据
data = {'name': '张三', 'age': 20, 'gender': '男'}
db.insert('students', data)

# 更新数据
data = {'name': '李四', 'age': 25}
condition = 'id=1'
db.update('students', data, condition)

# 删除数据
condition = 'id=2'
db.delete('students', condition)

# 查询数据
columns = ['name', 'age']
condition = 'gender="女"'
result = db.select('students', columns, condition)
print(result)

注意：以上代码只是一个示例，实际使用时需要根据具体情况进行修改。另外，为了安全起见，建议使用参数化查询来防止SQL注入攻击。