改變的數據表的結構與特定條件

Question

我有一個數據表prdData這樣

productid  text     linenumber typenumber 
100    this is the     0    2 
100    description of a1   2    2 
200    this is the name of a2  0    0 
100    this is the name of a1  0    0 
200    shortdescription of a2  0    1 

在此表中的產品數據被存儲。產品編號，產品名稱，簡短說明，長描述均爲數據存儲。如typenumber爲0其名稱，若爲1其簡短說明，並且其爲2其長描述。如果這些數據很長，那麼這些數據可能會出現在不同的行中。每行可以通過linenumber來識別第一行，它將是0下一個2等等。我想將此DataTable轉換爲另一個數據表這樣的

productId name     shortdescription    longdescription 
100   this is the name of a1        this is the description of a1 
200   this is the name of a2 shortdescription of a2 

任何人都可以告訴我怎麼能做到這一點？

Answer 1

您可以按產品，然後組產品按類型行組行：

var query = from r in table.AsEnumerable() 
      group r by r.Field<int>("productid") into g 
      let types = g.GroupBy(r => r.Field<int>("typenumber")) 
      select new { 
       productId = g.Key, 
       name = GetText(types.FirstOrDefault(t => t.Key == 0)), 
       shortdescription = GetText(types.FirstOrDefault(t => t.Key == 2)), 
       longdescription = GetText(types.FirstOrDefault(t => t.Key == 1)) 
     }; 

當輔助方法，只是訂單輸入行號行並返回串接文本

private static string GetText(IEnumerable<DataRow> rows) 
{ 
    if (rows == null) 
     return null; 

    var query = from r in rows 
       orderby r.Field<int>("linenumber") 
       select r.Field<string>("text"); 

    return String.Join(" ", query);     
} 

輸出：

[ 
    { 
    productId: 100, 
    name: "this is the name of a1", 
    shortdescription: "this is the description of a1", 
    longdescription: null 
    }, 
    { 
    productId: 200, 
    name: "this is the name of a2", 
    shortdescription: null, 
    longdescription: "shortdescription of a2" 
    } 
] 

---

您可以手動構建新的DataTable或使用此方法創建新的DataTable。你也可以使用LINQ構建以XML爲xml：

var xdoc = new XDocument(new XElement("products", 
       from p in query 
       select new XElement("product", 
        new XAttribute("productId", p.productId), 
        new XElement("name", p.name), 
        new XElement("shortDescription", p.shortdescription), 
        new XElement("longDescription", p.longdescription)))); 

輸出：

<products> 
    <product productId="100"> 
    <name>this is the name of a1</name> 
    <shortDescription>this is the description of a1</shortDescription> 
    <longDescription /> 
    </product> 
    <product productId="200"> 
    <name>this is the name of a2</name> 
    <shortDescription /> 
    <longDescription>shortdescription of a2</longDescription> 
    </product> 
</products> 

或（可能）更簡單的方案 - 而不是匿名類型的使用，創造出可以很容易地序列化爲XML定製類。