LEFT JOIN DataTables-如何使它工作? [英] LEFT JOIN DataTables - how do I get this to work?

问题描述

可能重复:
左外联接2个数据表

Possible Duplicate:
LEFT OUTER JOIN 2 datatables

让我们说这是我的确切代码:

Let's say this is my exact code:

        DataTable table1 = new DataTable();
        DataTable table2 = new DataTable();
        DataTable joinedtable = new DataTable();

        table1.Columns.Add("ID");
        table1.Columns.Add("ColA");
        table1.Rows.Add(1, "A");

        table2.Columns.Add("ID");
        table2.Columns.Add("ColB");
        table2.Rows.Add(1, "B");

我的查询(无论是否为LINQ)会如何处理，但是将table1和table2合并在一起并放入joinedTable中呢? 当我尝试搜索示例时，会不断查找以以下形式开头的示例:

What would my query, LINQ or not, but to left join table1 and table2 together and put it into joinedTable? When I try to search for examples, I keep finding examples that start like this:

        var result = from x in table1
            join y in table2 on x.ID equals y.ID 

但是，我在DataTable1上遇到错误，我发现建议改用"table1.AsEnumerable()"，但随后我没有x.ID.未定义.ID.我只有普通DataRow会拥有的x东西. 我在这里做错了什么?我似乎无法弄清楚.

But, I get an error on DataTable1 which I found a suggestion to instead do "table1.AsEnumerable()" but then I do not have a x.ID. .ID is not defined. I only have things for x that a normal DataRow would have. What am I doing wrong here? I cannot seem to figure this out.

谢谢大家的帮助.

推荐答案

使用DataTables不幸的是，它变得有些棘手(如果出于任何原因不想使用LINQ)，则需要定义 DataRelation 实际上是 的对象定义这两个DataTables之间的关系定义.

With DataTables it unfortunately becomes kind of tricky (if you don't want to use a LINQ for any reason), cause you need to define DataRelation object that actually define the relationship defintion between those two DataTables.

有关更多信息，请参见以下说明:

For more information can have a look on this explanation :

如何加入两个使用C#的数据表

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