Inner join to DataTables using LINQ in C#
Inner join is a relational database operation that retrieves data from two or more tables based on a common column. In C#, you can perform inner joins on DataTables using a variety of technologies, including LINQ.
LINQ method:
If LINQ is an option, the following code snippet demonstrates how to perform an inner join on two DataTables (T1 and T2):
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));
// 添加一些示例數(shù)據(jù)
for (int i = 1; i <= 5; i++)
{
dt1.Rows.Add(i, 10 + i, 20 + i);
dt2.Rows.Add(i, 30 + i);
}
// 使用LINQ執(zhí)行內(nèi)連接
var results = from table1 in dt1.AsEnumerable()
join table2 in dt2.AsEnumerable() on table1.Field<int>("CustID") equals table2.Field<int>("CustID")
select new
{
CustID = table1.Field<int>("CustID"),
ColX = table1.Field<int>("ColX"),
ColY = table1.Field<int>("ColY"),
ColZ = table2.Field<int>("ColZ")
};
// 輸出結(jié)果
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));
}
This LINQ query performs an inner join using the on clause, which specifies that the CustID columns of the two tables should be equal. The result is returned as an anonymous type containing the CustID, ColX, ColY, and ColZ columns.
Output:
This code will output the following results:
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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