XQuery表達式。有關訂購

Question

我必須訂購，然後打印出文本的一部分。我嘗試了一些表達式，最終成爲了可以幫助我的代碼，但我認爲它不太好。

我將發佈文本的一部分，然後發佈我所做的代碼。

<?xml version="1.0"?> 
<recipes> 
    <recipe> 
    <title>Beef Parmesan with Garlic Angel Hair Pasta</title> 
    <ingredient name="beef cube steak" amount="1.5" unit="pound"/> 
    <ingredient name="onion, sliced into thin rings" amount="1"/> 
    <ingredient name="green bell pepper, sliced in rings" amount="1"/> 
    <ingredient name="Italian seasoned bread crumbs" amount="1" unit="cup"/> 
    <ingredient name="grated Parmesan cheese" amount="0.5" unit="cup"/> 
    <ingredient name="olive oil" amount="2" unit="tablespoon"/> 
    <ingredient name="spaghetti sauce" amount="1" unit="jar"/> 
    <ingredient name="shredded mozzarella cheese" amount="0.5" unit="cup"/> 
    <ingredient name="angel hair pasta" amount="12" unit="ounce"/> 
    <ingredient name="minced garlic" amount="2" unit="teaspoon"/> 
    <ingredient name="butter" amount="0.25" unit="cup"/> 
    <preparation> 
     <step> 
     Preheat oven to 350 degrees F (175 degrees C). 
     </step> 
     <step> 
     Cut cube steak into serving size pieces. Coat meat with the bread crumbs 
     and parmesan cheese. Heat olive oil in a large frying pan, and saute 1 
     teaspoon of the garlic for 3 minutes. Quick fry (brown quickly on both sides) 
     meat. Place meat in a casserole baking dish, slightly overlapping edges. 
     Place onion rings and peppers on top of meat, and pour marinara sauce 
     over all. 
     </step> 
     <step> 
     Bake at 350 degrees F (175 degrees C) for 30 to 45 minutes, depending on 
     the thickness of the meat. Sprinkle mozzarella over meat and leave in the 
     oven till bubbly. 
     </step> 
     <step> 
     Boil pasta al dente. Drain, and toss in butter and 1 teaspoon garlic. For a 
     stronger garlic taste, season with garlic powder. Top with grated parmesan 
     and parsley for color. Serve meat and sauce atop a mound of pasta! 
     </step> 
    </preparation> 
    <comment> 
     Make the meat ahead of time, and refrigerate over night, the acid in the 
     tomato sauce will tenderize the meat even more. If you do this, save the 
     mozzarella till the last minute. 
    </comment> 
    <nutrition calories="1167" fat="23" carbohydrates="45" protein="32"/> 
    </recipe> 
<recipe> 
    <title>Ricotta Pie</title> 
    <ingredient name="filling"> 
     <ingredient name="ricotta cheese" amount="3" unit="pound"/> 
     <ingredient name="eggs" amount="12"/> 
     <ingredient name="white sugar" amount="2" unit="cup"/> 
     <ingredient name="vanilla extract" amount="2" unit="teaspoon"/> 
     <ingredient name="semisweet chocolate chips" amount="0.25" unit="cup"/> 
     <preparation> 
     <step> 
      Beat the 12 eggs, 2 cups sugar and vanilla extract together. Stir in 
      the ricotta cheese and the chocolate chips. Set aside. 
     </step> 
     </preparation> 
    </ingredient> 
    <ingredient name="dough"> 
     <ingredient name="flour" amount="4" unit="cup"/> 
     <ingredient name="baking powder" amount="5" unit="teaspoon"/> 
     <ingredient name="white sugar" amount="1" unit="cup"/> 
     <ingredient name="shortening" amount="0.5" unit="cup"/> 
     <ingredient name="eggs, lightly beaten" amount="4"/> 
     <ingredient name="vanilla extract" amount="1" unit="teaspoon"/> 
     <preparation> 
     <step> 
      Combine the flour, baking powder, and 1 cup of the sugar together. Cut in the 
      shortening and mix until the mixture resembles coarse crumbs. Mix in 4 of 
      the eggs and 1 teaspoon of the vanilla. Divide dough into 4 balls and chill (if 
      needed). 
     </step> 
     </preparation> 
    </ingredient> 
    <ingredient name="milk" amount="*"/> 
    <preparation> 
     <step> 
     Preheat oven to 325 degrees F (165 degrees C). Grease two deep dish pie 
     plates. 
     </step> 
     <step> 
     Roll out 2 of the balls to fit into the pie pans. Do not make the crust too thick 
     as it will expand during cooking and get too thick. Do not flute the edges of 
     the dough. Roll out the other 2 balls of dough and cut each into 8 narrow 
     strips for the top of the crust. Alternately you can use cookie cutters and 
     place the cutouts on the top of the pies. 
     </step> 
     <step> 
     Pour the filling evenly into the pie crusts. Top each pie with 8 narrow strips 
     of dough or cookie cut-outs. Brush top of pie with milk for shine. Place foil on 
     the edge of crust. 
     </step> 
     <step> 
     Bake at 325 degrees F (165 degrees C) for 20 to 30 minutes then remove 
     foil. Continue to bake for another 25 or 30 minutes or until a knife inserted in 
     the center comes out clean. 
     </step> 
    </preparation> 
    <nutrition calories="349" fat="18" carbohydrates="64" protein="18"/> 
    </recipe> 
> </recipes> 

我所做的代碼如下

<result> 
    { 
     for $x in doc()/recipes/recipe 
     order by $x/nutrition[@calories>600] 
     return 
      ($x/title) |($x/nutrition[@calories]) 
    } 
</result> 

XQuery表達式的主要思想是通過展示在熱量標籤<result>訂購的標題和卡路里。

Answer 1

您的第一次嘗試看起來不錯，除了結果XML看起來不太有用。您可能想要重新包裝配方元素中的每個標題和營養。其次，你的訂單條款可能不會做太多。你寫：

order by $x/nutrition[@calories>600] 

但是這樣你就可以通過營養元素的文本內容，它沒有任何。你大概的意思是：

order by $x/nutrition[@calories>600]/@calories 

或者甚至更好，你想上的熱量數值順序：

order by $x/nutrition[@calories>600]/@calories/fn:number(.) 

HTH！

Answer 2

我不太清楚你想要達到什麼目的。那麼calories > 600條件是什麼意思（它似乎沒有太多用於order by子句，因爲它只適用於排序條件）。我猜想，你想過濾掉所有營養價值低於600卡路里（你目前的聲明將排序超過600卡路里的一切，但其他人仍然會出現在結果中）。

此外，您確實想把@calories屬性作爲排序屬性，我猜是您想要實現的屬性。

<result> 
    { 
     for $x in doc()/recipes/recipe 
     return ($x/title, 
      for $n in $x/nutrition[@calories>600] 
      order by $n/@calories 
      return $n 
     ) 
    } 
</result>