Mysql 增删改查 写一个类

### MySQL增删改查类

```python
import mysql.connector

class MySQLHandler:
    def __init__(self, host, user, password, database):
        self.host = host
        self.user = user
        self.password = password
        self.database = database
        self.connection = mysql.connector.connect(
            host=self.host,
            user=self.user,
            password=self.password,
            database=self.database
        )
        self.cursor = self.connection.cursor()

    def execute_query(self, query):
        self.cursor.execute(query)
        self.connection.commit()
        return self.cursor.fetchall()

    def select(self, table, conditions=None):
        query = f"SELECT * FROM {table}"
        if conditions:
            query += f" WHERE {conditions}"
        return self.execute_query(query)

    def insert(self, table, values):
        query = f"INSERT INTO {table} VALUES {values}"
        self.execute_query(query)

    def update(self, table, new_values, conditions=None):
        set_values = ','.join([f'{key}={value}' for key, value in new_values.items()])
        query = f"UPDATE {table} SET {set_values}"
        if conditions:
            query += f" WHERE {conditions}"
        self.execute_query(query)

    def delete(self, table, conditions=None):
        query = f"DELETE FROM {table}"
        if conditions:
            query += f" WHERE {conditions}"
        self.execute_query(query)
        
    def close_connection(self):
        self.cursor.close()
        self.connection.close()

# Example Usage:
handler = MySQLHandler("localhost", "root", "password", "mydatabase")
result = handler.select("users", "age > 18")
print(result)
handler.insert("users", "('Alice', 25)")
handler.update("users", {"age": 26}, "name = 'Alice'")
handler.delete("users", "name = 'Alice'")
handler.close_connection()

This is a simple Python class for handling MySQL queries. It includes methods for selecting, inserting, updating, and deleting data from a given table. You can instantiate an object of this class with the necessary connection details and then perform database operations using the defined methods. The class utilizes the `mysql.connector` module for connecting to the MySQL database. You can see an example usage of this class at the bottom of the code snippet.

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