C # LINQ series: DataTable Operations for LINQ to Datasets and Conversion of DataTable and LINQ to each other

LINQ to datasets require the use of System.Core.dll, System.Data.dll and System.Data.DataSetExtensions.dll, add references System.Data and System.Data.DataSetExtensions to the project.

1. DataTable Read List

DataSet ds = new DataSet ();//Omit the DS's fill code datatable products = ds. tables["Product"];ienumerable<datarow> rows = from P in products. AsEnumerable ()                            Select P;foreach (DataRow row in rows) {    Console.WriteLine (row. Field<string> ("ProductName"));}

DataSet ds = new DataSet ();//Omit the DS's fill code datatable products = ds. tables["Product"];var rows = products. AsEnumerable ()    . Select (p = = new    {        ProductID = p.field<int> ("ProductID"),        ProductName = p.field<string> (" ProductName "),        UnitPrice = p.field<decimal> (" UnitPrice ")    }); foreach (var row in rows) {    Console.WriteLine (Row. ProductName);}

var products = ds. tables["Product"]. AsEnumerable (); var query = from P in            the products Select p.field<string> ("ProductName");

2. DataTable Query

var rows = products. AsEnumerable ()    . Where (P = = p.field<decimal> ("UnitPrice") > 10m)    . Select (p = = new    {        ProductID = p.field<int> ("ProductID"),        ProductName = p.field<string> (" ProductName "),        UnitPrice = p.field<decimal> (" UnitPrice ")    });

3. DataTable Data Sorting

var rows = products. AsEnumerable ()    . Where (P = = p.field<decimal> ("UnitPrice") > 10m)    . (p = p.field<int> ("SortOrder"))    . Select (p = = new    {        ProductID = p.field<int> ("ProductID"),        ProductName = p.field<string> ("ProductName"),        UnitPrice = p.field<decimal> ("UnitPrice")    });

var expr = from p in products. AsEnumerable ()            p.field<int> ("SortOrder")            select p;ienumerable<datarow> rows = Expr. ToArray (); foreach (var row in rows) {    Console.WriteLine (row). Field<string> ("ProductName"));}

var expr = from P in DS. tables["Product"]. AsEnumerable ()           p.field<int> ("SortOrder"), p.field<string> ("ProductName") descending           Select P;

4. Multiple DataTable queries

var query = from P in DS. tables["Product"]. AsEnumerable () from the            C in DS. tables["Category"]. AsEnumerable ()            where p.field<int> ("CategoryID") = = c.field<int> ("CategoryID")                && p. Field<decimal> ("UnitPrice") > 10m            Select New            {                ProductID = p.field<int> ("ProductID"),                ProductName = p.field<string> ("ProductName"),                CategoryName = c.field<string> ("CategoryName")            };

5. DataTable Grouping

var query = from P in DS. tables["Product"]. AsEnumerable ()            group P by p.field<int> ("CategoryID") into G            Select New            {                CategoryID = G.key, Products                = g            }; foreach (var item in query) {    Console.WriteLine (item. CategoryID);    foreach (var p in item. Products)    {        Console.WriteLine (p.field<string> ("ProductName"));}    }

Query the number of each CategoryID in product:

var expr = from P in DS. tables["Product"]. AsEnumerable ()           group P by p.field<int> ("CategoryID") into G           Select New           {               CategoryID = G.key,               Productscount = G.count ()           };

C # LINQ series: DataTable Operations for LINQ to Datasets and Conversion of DataTable and LINQ to each other