使用Linq连接4个DataTables

// 假设有四个DataTables：dt1、dt2、dt3、dt4

var query = from row1 in dt1.AsEnumerable()
            join row2 in dt2.AsEnumerable() on row1.Field<int>("ID") equals row2.Field<int>("ID")
            join row3 in dt3.AsEnumerable() on row1.Field<int>("ID") equals row3.Field<int>("ID")
            join row4 in dt4.AsEnumerable() on row1.Field<int>("ID") equals row4.Field<int>("ID")
            select new
            {
                ID = row1.Field<int>("ID"),
                Column1 = row1.Field<string>("Column1"),
                Column2 = row2.Field<string>("Column2"),
                Column3 = row3.Field<string>("Column3"),
                Column4 = row4.Field<string>("Column4")
            };

// 上述代码中，假设四个DataTables中都有一个名为ID的列，用于进行连接操作。
// 通过join关键字将四个DataTables连接在一起，并通过select关键字选择需要的列。

// 遍历查询结果
foreach (var result in query)
{
    Console.WriteLine("ID: " + result.ID);
    Console.WriteLine("Column1: " + result.Column1);
    Console.WriteLine("Column2: " + result.Column2);
    Console.WriteLine("Column3: " + result.Column3);
    Console.WriteLine("Column4: " + result.Column4);
    Console.WriteLine();
}