谁能给我一个更简单的解决方案？

我正在尝试查询数据库中的四个不同的表，并在 HTML 中使用非常奇怪的 FOR 模式对它们进行迭代。

由于数据库太大，我总是收到 MemoryError。

Python 脚本：

import sqlite3
con=sqlite3.connect('/home/sergiuster/Downloads/python/exportSQL.db', check_same_thread=False)
con.row_factory = sqlite3.Row

#QUERY MATERIALECARACT
cur = con.cursor()
cur.execute("SELECT MaterialeCaracteristici.CodProdus, MaterialeCaracteristici.Rollout, MaterialeCaracteristici.CatSezon, MaterialeCaracteristici.CodEAN, MaterialeCaracteristici.Descriere,MaterialeCaracteristici.Descriere, MaterialeCaracteristici.PretVz FROM MaterialeCaracteristici WHERE MaterialeCaracteristici.CodProdus LIKE 'VGF%' GROUP BY MaterialeCaracteristici.CodProdus")
row = cur.fetchall()

#QUERY STOC
cur2=con.cursor()
cur2.execute("SELECT StocTotal.CodProdus, Sum(StocTotal.Stoc) AS SumOfStoc FROM StocTotal WHERE StocTotal.CodProdus LIKE 'VGF%' GROUP BY StocTotal.CodProdus")
row2 = cur2.fetchall()

#QUERY VANZARI
cur3=con.cursor()
cur3.execute("SELECT dbo_VanzariCumulat.CodProdus,Sum(dbo_VanzariCumulat.Cant) AS SumOfCant FROM dbo_VanzariCumulat WHERE dbo_VanzariCumulat.CodProdus LIKE 'VGF%' AND dbo_VanzariCumulat.UnLg NOT LIKE 'SH-D101' GROUP BY dbo_VanzariCumulat.CodProdus")
row3 =cur3.fetchall()

#QUERY PA
cur4=con.cursor()
cur4.execute("SELECT dbo_PA.MTRL, dbo_PA.CodProdus, dbo_PA.PA FROM dbo_PA GROUP BY dbo_PA.MTRL, dbo_PA.CodProdus, dbo_PA.PA")
row4 =cur4.fetchall()


from flask import Flask, render_template, request
app = Flask(__name__)
app.debug = True

@app.route("/index")
def index():

    return render_template('index.html', object2 = row2, object = row, object3 = row3,object4 = row4)

HTML：

{% for obj in object %}

            VZ:
            {% for obj3 in object3 %}
              {% if obj3['CodProdus'] == obj['CodProdus'] %}
                          {{ obj3['CodProdus'] }}//
                          {{ obj3['SumOfCant']  | int}}<br>
              {% endif %}
            {% endfor %}

            STOC:
            {% for obj2 in object2 %}
              {% if obj2['CodProdus'] == obj['CodProdus'] %}
                          {{ obj2['CodProdus'] }}//
                          {{ obj2['SumOfStoc']  | int}}<br>
              {% endif %}
            {% endfor %}

            PA:
            {% for obj4 in object4 %}
              {% if obj4['CodProdus'] == obj['CodProdus'] %}
                  {{ obj4['CodProdus'] }}//
                  {{ obj4['PA']|round(2)|float}}<br>
                  {{(((obj['PretVz']/1.19)-obj4['PA'])/obj4['PA']*100)|round(2)|float}}%
              {% endif %}
           {% endfor %}
 {% endfor %}

有什么方法可以使用函数并从 HTML 调用它，以便它返回到 python 脚本，然后在 HTML 中返回 SumOfStoc 的值？

以下为示例：

#QUERY MATERIALECARACT
cur = con.cursor()
cur.execute("SELECT MaterialeCaracteristici.CodProdus, MaterialeCaracteristici.Rollout, MaterialeCaracteristici.CatSezon, MaterialeCaracteristici.CodEAN, MaterialeCaracteristici.Descriere,MaterialeCaracteristici.Descriere, MaterialeCaracteristici.PretVz FROM MaterialeCaracteristici WHERE MaterialeCaracteristici.CodProdus LIKE 'VGF%' GROUP BY MaterialeCaracteristici.CodProdus")
row = cur.fetchall()



def query_stoc(cod):  // I want to use MaterialeCaracteristici.CodProdus in html and pass it into this function, then return another value with the help of this function, in HTML;
    #QUERY STOC
    cur2=con.cursor()
    cur2.execute("SELECT StocTotal.CodProdus, Sum(StocTotal.Stoc) AS SumOfStoc FROM StocTotal WHERE StocTotal.CodProdus =? GROUP BY StocTotal.CodProdus", (cod))
    row2 = cur2.fetchall()
    return row2['SumOfStoc']

希望大家能理解我，不要让我出丑。任何帮助我的人都感激不尽！

谢谢。

解决方案

您可以采取以下几种措施来 1) 提高效率和 2) 简化当前代码：

首先，一个选项是创建一个类来处理不同的数据库连接。该类可以具有property可从相应表查询的属性。其次，不要使用cursor.fetchall将整个源加载到内存中的 ，而只需返回游标，因为您只需要在模板本身中迭代源一次。最后，可以将类实例作为单个参数传递给模板：

class db_Connector:
   def __init__(self, _file = '/home/sergiuster/Downloads/python/exportSQL.db'):
      self.filename = '/home/sergiuster/Downloads/python/exportSQL.db'
      self.conn = sqlite3.connect(self.filename, check_same_thread=False).cursor()
   @property
   def materialecaract(self):
     return self.conn.execute("SELECT MaterialeCaracteristici.CodProdus, MaterialeCaracteristici.Rollout, MaterialeCaracteristici.CatSezon, MaterialeCaracteristici.CodEAN, MaterialeCaracteristici.Descriere,MaterialeCaracteristici.Descriere, MaterialeCaracteristici.PretVz FROM MaterialeCaracteristici WHERE MaterialeCaracteristici.CodProdus LIKE 'VGF%' GROUP BY MaterialeCaracteristici.CodProdus")
   @property
   def stoc(self):
     return self.conn.execute("SELECT StocTotal.CodProdus, Sum(StocTotal.Stoc) AS SumOfStoc FROM StocTotal WHERE StocTotal.CodProdus LIKE 'VGF%' GROUP BY StocTotal.CodProdus")
   @property
   def vanzari(self):
     return self.conn.execute("SELECT dbo_VanzariCumulat.CodProdus,Sum(dbo_VanzariCumulat.Cant) AS SumOfCant FROM dbo_VanzariCumulat WHERE dbo_VanzariCumulat.CodProdus LIKE 'VGF%' AND dbo_VanzariCumulat.UnLg NOT LIKE 'SH-D101' GROUP BY dbo_VanzariCumulat.CodProdus")
   @property
   def pa(self):
      return self.conn.execute("SELECT dbo_PA.MTRL, dbo_PA.CodProdus, dbo_PA.PA FROM dbo_PA GROUP BY dbo_PA.MTRL, dbo_PA.CodProdus, dbo_PA.PA")

然后，在您提供模板的路线中：

@app.route("/index")
def index():
  return render_template('index.html', _object = db_Connector())

现在，在模板中，只需调用适当的属性：

{%for obj in _object.materialecaract%}

        VZ:
      {% for obj3 in _object.vanzari%}
         {% if obj3['CodProdus'] == obj['CodProdus'] %}
                      {{ obj3['CodProdus'] }}//
                      {{ obj3['SumOfCant']  | int}}<br>
          {% endif %}
        {% endfor %}

        STOC:
        {% for obj2 in _object.stoc %}
          {% if obj2['CodProdus'] == obj['CodProdus'] %}
                      {{ obj2['CodProdus'] }}//
                      {{ obj2['SumOfStoc']  | int}}<br>
          {% endif %}
        {% endfor %}

        PA:
        {% for obj4 in _object.pa %}
          {% if obj4['CodProdus'] == obj['CodProdus'] %}
              {{ obj4['CodProdus'] }}//
              {{ obj4['PA']|round(2)|float}}<br>
              {{(((obj['PretVz']/1.19)-obj4['PA'])/obj4['PA']*100)|round(2)|float}}%
          {% endif %}
       {% endfor %}
{% endfor %}