Python之数据库操纵工具

前言

• 基于原生模块：pymysql
• 推荐教程
  • Python 数据库处理的类库
    • pymysql [python原生模块]
    • SQLAchemy [ORM框架]
  • Python3 MySQL 数据库链接 - 菜鸟教程
• 小工具结构
  • DatabaseUtil([databseName])
    • getConnection()
    • query(sql)
    • save(sql)
    • delete(sql)
    • closeResources(cursor,connection)

源码

import pymysql # 导入mysql模块

## 数据库操纵工具
class DatabaseUtil:
    """
    database util / 数据库操纵工具
    ------------------------------
    [特别注意] 
        + pymysql.connect(...)函数
            + unix_socket
                + 本字段是使用 socket 链接才用到的，而咱们使用的是IP链接
                + 故：unix_socket='/tmp/mysql.sock' 改为 port=3306   
    """
    className = "DatabaseUtil";
    def __init__(self,database='default_db_name'):
        self.host='xxxx.com.cn';
        self.port = 3306;
        # unix_socket= "/tmp/mysql.sock",//module 'socket' has no attribute 'AF_UNIX'
        self.user='root';
        self.password='root';
        self.database=database;
        self.charset='utf8mb4';
        self.cursorclass=pymysql.cursors.DictCursor;
        pass;
    
    def getConnection(self):
        connection = None;
        connection = pymysql.connect(host=self.host,
                                 port=self.port,
                                 #  unix_socket= "/tmp/mysql.sock",//module 'socket' has no attribute 'AF_UNIX'
                                 user=self.user,
                                 password=self.password,
                                 database=self.database,
                                 charset=self.charset,
                                 cursorclass=self.cursorclass);
        # 切换数据库子模式
        # cursor.execute("USE "+str(self.database)); # 形如： USE db_demoDatabase 
           # 使用cursor()方法建立一个游标对象
        # cursor = connection.cursor();
        if connection == None:
            print("[",self.className,".getConnection] Fail to load and get database Connection!");
        return connection;
        pass;
    
    def query(self,sql):## 查 select
        # sql = "select * from tb_url limit 0,1000";  # just for test
        print("[",self.className,".query] SQL:",sql);
        connection = self.getConnection();
        cursor = connection.cursor();
        try:
            cursor.execute(sql) # 执行SQL语句
            # sql = "select * from userinfo where username=%(u)s and password=%(p)s"
            # cursor.execute(sql,user,pwd)  #直接传值
            # cursor.execute(sql,[user,pwd]) #列表形式
            # cursor.execute(sql,{'u':user,'p':pwd}) #字典格式
            # print("row number:",(cursor.rownumber))
            # print("rowcount:",cursor.rowcount); # 只读属性，并返回执行execute()方法后影响的行数
            # 获取全部记录列表
            #results = print("row [1]: ", cursor.fetchone()); # 获取下一个查询结果集。结果集是一个对象
            if cursor.rowcount < 1:
                print("[",self.className,".query] Not found any data from database!")
                return;
            results = None; # 初始化
            # + cursor.fetchone() 获取下一行数据，第一次为首行
            # + cursor.fetchall() 获取全部行数据源
            # + cursor.fetchmany(n) 获取下N行数据
            results = cursor.fetchall(); # 接收所有的返回结果行.
            # print("results:",results);
            # print("results[0]:",results[0]);
            i = 0; #记录计数
            for row in results: # row ：字典类型
                object = [];#存储各字段信息
                for key in row:
                    object.append(row[key]);
                    # print("[", i , "] " , key , " : " , row[key]);
                    pass;
                i+=1;
                # 打印结果
                # print("Url {\n\tpk_url_id:%s,\n\tstate:%s,\n\turl:%s,\n\tresolve_type:%s,\n\tresolver_class_bean:%s\n}" % (object[0], object[1], object[2], object[3], object[4]))
        except e:
            print("[",self.className,".query] ",e.message);
            print("[",self.className,".query] Error: unable to fetch data!")
            pass;
        self.closeResources(cursor,connection);
        return results; # 以结果行为字典类型的数组 [{ key1:value1, key2:value2 }]
        pass;

    def save(self,sql): ## 插 insert / 更新 update
        # sql = "UPDATE EMPLOYEE SET AGE = AGE + 1 WHERE SEX = '%c'" % ('M')
        # sql = "insert into tb_url values('2','WAITING_RESOLVE','http://test.for.python.mysql.cn','article/author','resolver_class_bean:Unknown')";
        print("[",self.className,".save] SQL:",sql);
        connection = self.getConnection();
        cursor = connection.cursor();
        result = -100; # 初始化一个异常值
        try:
            # 执行sql语句
            result = cursor.execute(sql);
            # print("[",className,".insert] the last rowId is ",cursor.lastrowid) # 当表中有自增的主键的时候，能够使用lastrowid来获取最后一次自增的ID
            # 提交到数据库执行
            connection.commit();
        except:
            # 若是发生错误则回滚
            connection.rollback();
            pass;
        self.closeResources(cursor,connection);
        if result == 1:
            print("[",self.className,".save] Done!");
        else:
            print("[",self.className,".save] Failed!")
            pass;
        # print("[",self.className,".insert] result:",result)
        return result;
        pass;
    
    def delete(self,sql): # 删除 delete
        # sql = "DELETE FROM EMPLOYEE WHERE AGE > %s" % (20)
        print("[",self.className,".delete] SQL:",sql);
        connection = self.getConnection();
        cursor = connection.cursor();
        result = -100; # 初始化一个异常值
        try:
            # 执行sql语句
            result = cursor.execute(sql);
            # print("[",className,".insert] the last rowId is ",cursor.lastrowid) # 当表中有自增的主键的时候，能够使用lastrowid来获取最后一次自增的ID
            # 提交到数据库执行
            connection.commit();
        except:
            # 若是发生错误则回滚
            connection.rollback();
            pass;
        self.closeResources(cursor,connection);
        if result == 1:
            print("[",self.className,".delete] Done!");
        else:
            print("[",self.className,".delete] Failed!")
            pass;
        # print("[",self.className,".insert] result:",result)
        return result;
        pass;
    
    def closeResources(self,cursor,connection):
        try:
            cursor.close() # 关闭数据库游标对象
            connection.close() # 关闭数据库链接
            pass;
        except e:
            print (e.message);
            pass;
        pass;
    pass; # class end

Demo

# 插 / 更新
    # sql = "insert into tb_url values('5','WAITING_RESOLVE','http://test.for.python.mysql.cn','article/author','resolver_class_bean:Unknown')";
    # print(dbUtil.save(sql));

    # 删
    # for i in range(2,5):[2,5)
    #     sql = "delete from tb_url where pk_url_id='%d'" % (i);
    #     dbUtil.delete(sql);
    #     pass;

    # 查
sql = "select * from tb_url where pk_url_id='%s'" % ('5'); 
print(dbUtil.query(sql));

//output
[ DatabaseUtil .query] SQL: select * from tb_url where pk_url_id='5'
[{'pk_url_id': 5, 'state': 'WAITING_RESOLVE', 'url': 'http://test.for.python.mysql.cn', 'resolve_type': 'article/author', 'resolver_class_bean': 'resolver_class_bean:Unknown'}]