小议数据库主键选取策略

/**//// <summary>

/// 从 SQL SERVER 返回的 GUID 中生成时间信息

/// </summary>

/// <param name="guid">包含时间信息的 COMB </param>

/// <returns>时间</returns>

public static DateTime GetDateFromComb(System.Guid guid)

{

DateTime baseDate = new DateTime(1900,1,1);

byte[] daysArray = new byte[4];

byte[] msecsArray = new byte[4];

byte[] guidArray = guid.ToByteArray();

// Copy the date parts of the guid to the respective byte arrays.

Array.Copy(guidArray, guidArray.Length - 6, daysArray, 2, 2);

Array.Copy(guidArray, guidArray.Length - 4, msecsArray, 0, 4);

// Reverse the arrays to put them into the appropriate order

Array.Reverse(daysArray);

Array.Reverse(msecsArray);

// Convert the bytes to ints

int days = BitConverter.ToInt32(daysArray, 0);

int msecs = BitConverter.ToInt32(msecsArray, 0);

DateTime date = baseDate.AddDays(days);

date = date.AddMilliseconds(msecs * 3.333333);

return date;

}

　　结语

　　数据库主键在数据库中占有重要地位。主键的选取策略决定了系统是否高效、易用。本文比较了四种主键选取策略的优缺点，并提供了相应的代码解决方案，希望对大家有所帮助。