前导填充变量为零的SQL标识

在这种情况下,将计算的持久化列添加到具有此填充内容的SQL表中要容易得多:

ALTER TABLE dbo.YourTable
  ADD PaddedID AS RIGHT('00000' + CAST(ID AS VARCHAR(5)), 5) PERSISTED

作为持久化列,数据实际上是存储的(不是在每次访问时计算),因此速度很快。现在选择这个 PaddedID 为你的下拉框列,你很好去!

最后,它在linq to sql中完成,存储“pad length”

/// <summary>
    /// Calculate the amount of padding needed for this object
    /// </summary>
    /// <returns></returns>
    private static int _padLength = -1;
    private static int PadLength()
    {
        if (_padLength < 0)
        {
            Aurora.Data.AuroraDataContext db = new AuroraDataContext();
            _padLength = (from r in db.KpiForms select r.Id).Max().ToString().Length;
        }

        return _padLength;
    }

    /// <summary>
    /// Returns the display value for combo boxes
    /// </summary>
    public string DropDownDisplayTitle
    {
        get
        {
            if (this.Id <= 0) return 0.ToString().PadLeft(PadLength(), '0') + " " + this.Title ;
            return this.Id.ToString().PadLeft(PadLength(), '0') + " " + this.Title ;
        }
    }

也就是说,它是有效的,而且性能在这一点上会受到影响。