C# 6.0 内插字符串(Interpolated Strings )的使用方法

var city = "London";

using (var context = CreateContext())
{
 context.Customers
  .FromSql($@"
   SELECT *
   FROM Customers
   WHERE City = {city}")
  .ToArray();
}

@p0='London' (Size = 4000)

SELECT *
FROM Customers
WHERE City = @p0

var name = "world";
Console.WriteLine($"hello {name}");

var name = "world";
string str1 = $"hello {name}"; //等于 var str1 = $"hello {name}";
IFormattable str2 = $"hello {name}";
FormattableString str3 = $"hello {name}";

var name = "world";
string str1 = string.Format("hello {0}",name); //等于 var str1 = $"hello {name}";
IFormattable str2 = FormattableStringFactory.Create("hello {0}",name);
FormattableString str3 = FormattableStringFactory.Create("hello {0}",name);

var name = "world";
FormattableString fmtString = $"hello {name}";
Console.WriteLine(fmtString.ArgumentCount); //1
Console.WriteLine(fmtString.Format); //hello {0}
foreach (var arg in fmtString.GetArguments())
{
 Console.WriteLine(arg); //world
 Console.WriteLine(arg.GetType()); //System.String
}

var city = "London";

using (var context = CreateContext())
{
 //方法一，非参数化
 var sql = $" SELECT * FROM Customers WHERE City = {city}";
 context.Customers.FromSql(sql).ToArray();

 //方法二，参数化
 context.Customers.FromSql($" SELECT * FROM Customers WHERE City = {city}").ToArray();

 //方法三，参数化
 FormattableString fsql = $" SELECT * FROM Customers WHERE City = {city}";
 context.Customers.FromSql(fsql).ToArray();

 //方法四，非参数化
 var sql = " SELECT * FROM Customers WHERE City = @p0";
 context.Customers.FromSql(sql, city).ToArray();

}