FWIW，对于MS-SQL，这个表达式将完成工作。将第一个WHEN (WHEN num % 100 IN (11,12,13) THEN 'th')作为列表中的第一个，因为这依赖于在其他尝试之前尝试。

CASE
  WHEN num % 100 IN (11, 12, 13) THEN 'th' -- must be tried first
  WHEN num % 10 = 1 THEN 'st'
  WHEN num % 10 = 2 THEN 'nd'
  WHEN num % 10 = 3 THEN 'rd'
  ELSE 'th'
END AS Ordinal

对于Excel:

=MID("thstndrdth",MIN(9,2*RIGHT(A1)*(MOD(A1-11,100)>2)+1),2)

表达式(MOD(A1- 11100)>2)对于除以11,12,13结尾的任何数字(FALSE = 0)外的所有数字都是TRUE(1)。因此2 * RIGHT(A1) * (MOD(A1- 11100)>2) +1)对于11/12/13最终为1，否则: 1等于3 2点到5点， 3至7点 其他:9 -所需的2个字符从该位置开始的“第thstndrdth”中选择。

如果你真的想把它直接转换成SQL，这对我来说适用于一些测试值:

DECLARE @n as int
SET @n=13
SELECT SubString(  'thstndrdth'
                 , (SELECT MIN(value) FROM
                     (SELECT 9 as value UNION
                      SELECT 1+ (2* (ABS(@n) % 10)  *  CASE WHEN ((ABS(@n)+89) % 100)>2 THEN 1 ELSE 0 END)
                     ) AS Mins
                   )
                 , 2
                )

这里是DateTime扩展类。复制，粘贴和享受

public static class DateTimeExtensions
{
    public static string ToStringWithOrdinal(this DateTime d)
    {
        var result = "";
        bool bReturn = false;            
        
        switch (d.Day % 100)
        {
            case 11:
            case 12:
            case 13:
                result = d.ToString("dd'th' MMMM yyyy");
                bReturn = true;
                break;
        }

        if (!bReturn)
        {
            switch (d.Day % 10)
            {
                case 1:
                    result = d.ToString("dd'st' MMMM yyyy");
                    break;
                case 2:
                    result = d.ToString("dd'nd' MMMM yyyy");
                    break;
                case 3:
                    result = d.ToString("dd'rd' MMMM yyyy");
                    break;
                default:
                    result = d.ToString("dd'th' MMMM yyyy");
                    break;
            }

        }

        if (result.StartsWith("0")) result = result.Substring(1);
        return result;
    }
}

结果:

2014年10月9日

我使用的另一种替代方法是基于所有其他建议，但不需要特殊的大小写:

public static string DateSuffix(int day)
{
    if (day == 11 | day == 12 | day == 13) return "th";
    Math.DivRem(day, 10, out day);
    switch (day)
    {
        case 1:
            return "st";
        case 2:
            return "nd";
        case 3:
            return "rd";
        default:
            return "th";
    }
}

c# 8和9中接受的带有开关表达式和模式匹配的答案。

没有不必要的字符串转换或分配。

string.Concat(number, number < 0 ? "" : (number % 100) switch 
{   
    11 or 12 or 13 => "th", 
    int n => (n % 10) switch 
    { 
        1 => "st", 
        2 => "nd", 
        3 => "rd", 
        _ => "th", 
    }
})

或者是不友好的一句话:

$"{number}{(number < 0 ? "" : (number % 100) switch { 11 or 12 or 13 => "th", int n => (n % 10) switch { 1 => "st", 2 => "nd", 3 => "rd", _ => "th" }})}"

public static string OrdinalSuffix(int ordinal)
{
    //Because negatives won't work with modular division as expected:
    var abs = Math.Abs(ordinal); 

    var lastdigit = abs % 10; 

    return 
        //Catch 60% of cases (to infinity) in the first conditional:
        lastdigit > 3 || lastdigit == 0 || (abs % 100) - lastdigit == 10 ? "th" 
            : lastdigit == 1 ? "st" 
            : lastdigit == 2 ? "nd" 
            : "rd";
}

private static string GetOrd(int num) => $"{num}{(!(Range(11, 3).Any(n => n == num % 100) ^ Range(1, 3).All(n => n != num % 10)) ? new[] { "ˢᵗ", "ⁿᵈ", "ʳᵈ" }[num % 10 - 1] : "ᵗʰ")}";

如果有人在找一句俏皮话。