DataTable的Select方法

DataTable的Select方法

获取 DataRow 对象的数组。
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名称 说明

Select() 获取所有 DataRow 对象的数组。

Select(String)

按照主键顺序（如果没有主键，则按照添加顺序）获取与筛选条件相匹配的所有 DataRow 对象的数组。

Select(String, String)

获取按照指定的排序顺序且与筛选条件相匹配的所有 DataRow 对象的数组。

Select(String, String, DataViewRowState)

获取与排序顺序中的筛选器以及指定的状态相匹配的所有 DataRow 对象的数组。
示例：
private void GetRows()

{

// Get the DataTable of a DataSet.

DataTable table = DataSet1.Tables["Suppliers"];

DataRow[] rows = table.Select();

// Print the value one column of each DataRow.

for(int i = 0; i < rows.Length ; i++)

{

Console.WriteLine(rows[i]["CompanyName"]);

}

}
//**********************************************************************************************************

private void GetRowsByFilter(){    DataTable table = DataSet1.Tables["Orders"];    // Presuming the DataTable has a column named Date.    string expression;    expression = "Date > #1/1/00#";    DataRow[] foundRows;    // Use the Select method to find all rows matching the filter.    foundRows = table.Select(expression);    // Print column 0 of each returned row.    for(int i = 0; i < foundRows.Length; i ++)    {        Console.WriteLine(foundRows[i][0]);    }}

//**********************************************************************************************************
private void GetRowsByFilter()

{

DataTable table = DataSet1.Tables["Orders"];

// Presuming the DataTable has a column named Date.

string expression = "Date > '1/1/00'";

// Sort descending by column named CompanyName.

string sortOrder = "CompanyName DESC";

DataRow[] foundRows;

// Use the Select method to find all rows matching the filter.

foundRows = table.Select(expression, sortOrder);

// Print column 0 of each returned row.

for(int i = 0; i < foundRows.Length; i ++)

{

Console.WriteLine(foundRows[i][0]);

}

}
//**********************************************************************************************************
private static void GetRowsByFilter()

{

DataTable customerTable = new DataTable("Customers");

// Add columns

customerTable.Columns.Add("id", typeof(int));

customerTable.Columns.Add("name", typeof(string));

// Set PrimaryKey

customerTable.Columns[ "id" ].Unique = true;

customerTable.PrimaryKey = new DataColumn[]

{ customerTable.Columns["id"] };

// Add ten rows

for(int id=1; id<=10; id++)

{

customerTable.Rows.Add(

new object[] { id, string.Format("customer{0}", id) });

}

customerTable.AcceptChanges();

// Add another ten rows

for(int id=11; id<=20; id++) { customerTable.Rows.Add( new object[] { id, string.Format("customer{0}",
id) });

}

string expression;

string sortOrder;

expression = "id > 5";

// Sort descending by column named CompanyName.

sortOrder = "name DESC";

// Use the Select method to find all rows matching the filter.

DataRow[] foundRows =

customerTable.Select(expression, sortOrder,

DataViewRowState.Added);

PrintRows(foundRows, "filtered rows");

foundRows = customerTable.Select();

PrintRows(foundRows, "all rows");

}

private static void PrintRows(DataRow[] rows, string label)

{

Console.WriteLine("\n{0}", label);

if(rows.Length <= 0)

{

Console.WriteLine("no rows found");

return;

}

foreach(DataRow row in rows)

{

foreach(DataColumn column in row.Table.Columns)

{

Console.Write("\table {0}", row[column]);

}

Console.WriteLine();

}

}