Ubuntu 下 Python 连接 KingbaseES 数据库实现增删改查

3. 创建测试表

在执行增删改查前，先构建一张测试表。注意 SQL 语句应作为字符串变量存储，避免语法错误。

def create_table(conn):
    try:
        cursor = conn.cursor()
        create_table_sql = """
        CREATE TABLE IF NOT EXISTS user_info (
            id INTEGER PRIMARY KEY,
            username VARCHAR(50) NOT NULL,
            age INTEGER,
            created_time TIMESTAMP DEFAULT CURRENT_TIMESTAMP
        )
        """
        cursor.execute(create_table_sql)
        conn.commit()
        cursor.close()
        print("表创建成功")
    except Exception as e:
        print(f"创建表失败：{e}")
        conn.rollback()

if connection:
    create_table(connection)

4. 实现增删改查功能

为了代码整洁，我们将常用操作封装进一个管理类。这样既能处理单条数据，也能批量操作，同时自动管理事务提交与回滚。

4.1 封装数据库管理类

该类统一了连接、查询、更新和断开的逻辑，解决了硬编码重复的问题。

import ksycopg2
from datetime import datetime

class KingbaseESManager:
    def __init__(self, dbname, user, password, host, port):
        self.conn = None
        self.db_params = {
            "database": dbname,
            "user": user,
            "password": password,
            "host": host,
            "port": port
        }

    def connect(self):
        try:
            self.conn = ksycopg2.connect(**self.db_params)
            print("数据库连接成功")
            return True
        except Exception as e:
            print(f"连接数据库失败：{e}")
            return False

    def disconnect(self):
        if self.conn:
            self.conn.close()
            print("数据库连接已关闭")

    def execute_query(self, sql, params=None):
        try:
            cursor = self.conn.cursor()
            if params:
                cursor.execute(sql, params)
            else:
                cursor.execute(sql)
            results = cursor.fetchall()
            cursor.close()
            return results
        except Exception as e:
            print(f"查询执行失败：{e}")
            return None

    def execute_update(self, sql, params=None):
        try:
            cursor = self.conn.cursor()
            if params:
                cursor.execute(sql, params)
            else:
                cursor.execute(sql)
            self.conn.commit()
            affected_rows = cursor.rowcount
            cursor.close()
            print(f"操作成功，影响行数：{affected_rows}")
            return affected_rows
        except Exception as e:
            self.conn.rollback()
            print(f"操作执行失败：{e}")
            return -1

    def insert_user(self, id, username, age):
        sql = "INSERT INTO user_info (id, username, age) VALUES (%s, %s, %s)"
        params = (id, username, age)
        return self.execute_update(sql, params)

    def select_all_users(self):
        sql = "SELECT * FROM user_info ORDER BY id"
        return self.execute_query(sql)

    def select_user_by_id(self, id):
        sql = "SELECT * FROM user_info WHERE id = %s"
        params = (id,)
        return self.execute_query(sql, params)

    def update_user_age(self, id, new_age):
        sql = "UPDATE user_info SET age = %s WHERE id = %s"
        params = (new_age, id)
        return self.execute_update(sql, params)

    def delete_user(self, id):
        sql = "DELETE FROM user_info WHERE id = %s"
        params = (id,)
        return self.execute_update(sql, params)

    def search_users_by_age_range(self, min_age, max_age):
        sql = "SELECT * FROM user_info WHERE age BETWEEN %s AND %s ORDER BY age"
        params = (min_age, max_age)
        return self.execute_query(sql, params)

4.2 业务逻辑调用示例

下面展示如何使用上述类完成典型的数据操作流程。

if __name__ == "__main__":
    db_manager = KingbaseESManager(
        dbname="TEST",
        user="SYSTEM",
        password="qwe123!@#",
        host="127.0.0.1",
        port="54321"
    )

    if db_manager.connect():
        # 插入多条用户数据
        users_to_insert = [
            (1, '张三', 25),
            (2, '李四', 30),
            (3, '王五', 28),
            (4, '赵六', 35),
            (5, '钱七', 22)
        ]
        for user in users_to_insert:
            db_manager.insert_user(*user)

        # 查询所有用户
        print("所有用户信息:")
        all_users = db_manager.select_all_users()
        for user in all_users:
            print(user)

        # 根据 ID 查询特定用户
        print("\n查询 ID 为 2 的用户:")
        user_by_id = db_manager.select_user_by_id(2)
        print(user_by_id)

        # 更新用户年龄
        print("\n更新张三的年龄为 26:")
        db_manager.update_user_age(1, 26)

        # 范围查询
        print("\n年龄在 25-30 岁之间的用户:")
        users_by_age = db_manager.search_users_by_age_range(25, 30)
        for user in users_by_age:
            print(user)

        # 删除用户
        print("\n删除 ID 为 5 的用户:")
        db_manager.delete_user(5)

        # 再次验证
        print("\n删除后的所有用户:")
        remaining_users = db_manager.select_all_users()
        for user in remaining_users:
            print(user)

        db_manager.disconnect()

5. 验证与调试

运行脚本后，建议在命令行工具中直接登录数据库进行二次验证，确保数据持久化无误。

# 切换到 kingbase 用户
su - kingbase
# 连接数据库
ksql -U SYSTEM -d test -p 54321
# 执行查询
SELECT * FROM user_info ORDER BY id;

如果在命令行无法连接，可指定完整路径：

/kingbase/data/KESRealPro/V009R002C012/Server/bin/ksql -U SYSTEM -d test -p 54321

通过这种方式，你可以快速确认 Python 脚本对数据库的操作是否生效。遇到权限或连接问题时，优先检查 LD_LIBRARY_PATH 设置及防火墙策略。