常在寫SQL習慣了，應該很習慣以下語法
Select id from Product
Where type in ('PC', 'NB');
在Linq 中，沒這麼快快樂樂 XXX in (AAA, BBB) 的語法，必須要改用 Contains，
今天就遇到一個茶包問題，萬一我的產品有 PC, Dell_PC，用Contains 下去查 PC 的品項，Dell_PC也跑出來呢?
https://dotnetfiddle.net/BsNLvJ
用以下的小範例驗證，結果是一樣的，並無查詢 A，跑出 Acer, ASUS 的情形。
public static void Main()
{
var list = new List<string>() {"ASUS_PC","Acer_PC","BenQ", "Toshiba","IBM","HP","Dell"};
var ss = new List<string>() {"PC", "IBM", "Acer_PC", "A"};
string s2 = "PC, IBM, Acer_PC, A";
var r0 = list.Where(l => ss.Contains(l));
var r1 = list.Where(l => s2.Contains(l));
var r2 = list.Where(l => ss.Any(p => p.Equals(l)));
Console.WriteLine("List Contains Case");
foreach (var item in r0)
{
Console.WriteLine(item);
}
Console.WriteLine();
Console.WriteLine("String Contains Case");
foreach (var item in r1)
{
Console.WriteLine(item);
}
Console.WriteLine();
Console.WriteLine("List equals Case");
foreach (var item in r2)
{
Console.WriteLine(item);
}
Console.WriteLine();
}
Result:
List Contains Case
Acer_PC
IBM
String Contains Case
Acer_PC
IBM
List equals Case
Acer_PC
IBM
Ref.
https://stackoverflow.com/questions/1075540/linq-to-sql-how-to-do-where-column-in-list-of-values
https://stackoverflow.com/questions/1175645/find-an-item-in-list-by-linq