把數據庫的操作封裝成類，以及一些簡便方法

為了提高數據庫的操作速度，避免重復的進入和退出，我們可以把一些常用的數據庫的操作封裝成一個類。

 

把數據庫操作寫成函數：每次都得連接數據庫一次連接一次提交，重復操作浪費時間

把數據庫操作寫成類：一次連接可以多次提交，最佳重復操作時不需要關閉數據庫

 

import pymysql

class SQLManager(object):

    def __init__(self): #實例化后自動執行此函數
        self.connect()

    def connect(self): #此時進入數據庫，游標也已經就緒
        self.conn = pymysql.connect(host="127.0.0.1", port=3306, user="root", passwd="123", db="day66", charset="utf8")
        self.cursor = self.conn.cursor(cursor=pymysql.cursors.DictCursor)

    def get_list(self, sql, args=None):
        self.cursor.execute(sql, args)
        result = self.cursor.fetchall()
        return result

    def get_one(self, sql, args=None):
        self.cursor.execute(sql, args)
        result = self.cursor.fetchone()
        return result


    def run(self, sql, args=None):
        self.cursor.execute(sql, args)
        self.conn.commit()

    def create(self, sql, args=None):
        self.cursor.execute(sql, args)
        self.conn.commit()
        ret = self.cursor.lastrowid  # 取到剛才創建的記錄的ID
        return ret

    def m_create(self, sql, args=None):
        # self.cursor.executemany(sql, [(1, 36), (1, 38), (1, 36)])
        self.cursor.executemany(sql, args)  # 批量執行
        self.conn.commit()
        ret = self.cursor.lastrowid  # 取到剛才創建的記錄的ID
        return ret

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

 

 有時候可能會忘記關閉數據庫，

With 定義函數的時候有兩個方法，一個叫__enter__

另一個叫__exit__

后面的參數不用管

 

 

 

import pymysql
class SQLManager(object):

    def __init__(self):
        self.connect()

    def connect(self):
        self.conn = pymysql.connect(host="127.0.0.1", port=3306, user="root", passwd="", db="mysite", charset="utf8")
        self.cursor = self.conn.cursor(cursor=pymysql.cursors.DictCursor)

    def get_list(self, sql, args=None):
        self.cursor.execute(sql, args)
        result = self.cursor.fetchall()
        return result

    def get_one(self, sql, args=None):
        self.cursor.execute(sql, args)
        result = self.cursor.fetchone()
        return result


    def run(self, sql, args=None):
        self.cursor.execute(sql, args)
        self.conn.commit()

    def create(self, sql, args=None):
        self.cursor.execute(sql, args)
        self.conn.commit()
        ret = self.cursor.lastrowid  # 取到剛才創建的記錄的ID
        return ret

    def m_create(self, sql, args=None):
        # self.cursor.executemany(sql, [(1, 36), (1, 38), (1, 36)])
        self.cursor.executemany(sql, args)  # 批量執行
        self.conn.commit()
        ret = self.cursor.lastrowid  # 取到剛才創建的記錄的ID
        return ret

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

    def __enter__(self):
        print("startttttttttttttttt........")
        return self

    def __exit__(self, exc_type, exc_val, exc_tb):
        self.close()
        print("closeeeeeeeeeeeeeeeeeeee.....")

執行的例子：

def modal_teacher_list(request):
    teacher_id = request.GET.get("teacher_id")
    with SQLManager() as db:
        class_ids_o = db.get_list("select class_id from teacher2class WHERE teacher_id=%s", [teacher_id])
    print(class_ids_o)
    class_ids = [i["class_id"] for i in class_ids_o]
    return HttpResponse(json.dumps(class_ids))