C#中数据表的内连接 [英] Inner join of DataTables in C#

问题描述

设 T1 和 T2 是具有以下字段的 DataTables

Let T1 and T2 are DataTables with following fields

T1(CustID, ColX, ColY)

T2(CustID, ColZ)

我需要联合表

TJ (CustID, ColX, ColY, ColZ)

如何在 C# 代码中以简单的方式完成此操作?谢谢.

How this can be done in C# code in a simple way? Thanks.

推荐答案

如果你被允许使用 LINQ，看看下面的例子.它创建两个带有整数列的数据表，用一些记录填充它们，使用 LINQ 查询连接它们并将它们输出到控制台.

If you are allowed to use LINQ, take a look at the following example. It creates two DataTables with integer columns, fills them with some records, join them using LINQ query and outputs them to Console.

    DataTable dt1 = new DataTable();
    dt1.Columns.Add("CustID", typeof(int));
    dt1.Columns.Add("ColX", typeof(int));
    dt1.Columns.Add("ColY", typeof(int));

    DataTable dt2 = new DataTable();
    dt2.Columns.Add("CustID", typeof(int));
    dt2.Columns.Add("ColZ", typeof(int));

    for (int i = 1; i <= 5; i++)
    {
        DataRow row = dt1.NewRow();
        row["CustID"] = i;
        row["ColX"] = 10 + i;
        row["ColY"] = 20 + i;
        dt1.Rows.Add(row);

        row = dt2.NewRow();
        row["CustID"] = i;
        row["ColZ"] = 30 + i;
        dt2.Rows.Add(row);
    }

    var results = from table1 in dt1.AsEnumerable()
                 join table2 in dt2.AsEnumerable() on (int)table1["CustID"] equals (int)table2["CustID"]
                 select new
                 {
                     CustID = (int)table1["CustID"],
                     ColX = (int)table1["ColX"],
                     ColY = (int)table1["ColY"],
                     ColZ = (int)table2["ColZ"]
                 };
    foreach (var item in results)
    {
        Console.WriteLine(String.Format("ID = {0}, ColX = {1}, ColY = {2}, ColZ = {3}", item.CustID, item.ColX, item.ColY, item.ColZ));
    }
    Console.ReadLine();

// Output:
// ID = 1, ColX = 11, ColY = 21, ColZ = 31
// ID = 2, ColX = 12, ColY = 22, ColZ = 32
// ID = 3, ColX = 13, ColY = 23, ColZ = 33
// ID = 4, ColX = 14, ColY = 24, ColZ = 34
// ID = 5, ColX = 15, ColY = 25, ColZ = 35

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