c#如何将sql数据库中多条出生日期转换成年龄

 public class Person
        {
            public String Name;
            public DateTime birthday;
            public Int32 Age;
        }

        private void button1_Click(object sender, EventArgs e)
        {
            database db = new database();
            string sql = "select * from JZK_pat where times=1";
            SqlDataReader mydr;
            db.runsql(sql, out mydr);
            while (mydr.Read())
            {
                Person item = new Person();
                int index = mydr.GetOrdinal("birthday");
                item.birthday = mydr.IsDBNull(index) ? new DateTime("1900-01-01") : mydr.GetDateTime(index);
                item.Age = DateTime.Now.Year - item.birthday.Year;
                listBox1.Items.Add(item);
            }
            mydr.Close();  
        }

sql数据库中有多条数据，字段名包括（姓名，性别，出生日期）

想用winform程序的textbox.Item显示出所有数据，但显示的格式为每一行（姓名，性别，年龄）

自己做的是SqlDataReader，但在while循环里无法实现多条出生日期转换成年龄

我是新手，请大神们指导一下，谢谢

字符串用 DateTime.Parse转，而不是new DateTime，ide会有参数类型提示，除非你用记事本来编写代码
 

public int GetAgeByBirthdate(DateTime birthdate)
    {
        DateTime now = DateTime.Now;
        int age = now.Year - birthdate.Year;
        if (now.Month < birthdate.Month || (now.Month == birthdate.Month && now.Day < birthdate.Day))
        {
            age--;
       }
       return age < 0 ? 0 : age;
   }
public class Person
{
public String Name;
public DateTime birthday;
public Int32 Age;
}


private void button1_Click(object sender, EventArgs e)
{
database db = new database();
string sql = "select * from JZK_pat where times=1";
SqlDataReader mydr;
db.runsql(sql, out mydr);
while (mydr.Read())
{
Person item = new Person();
int index = mydr.GetOrdinal("birthday");
item.birthday = mydr.IsDBNull(index) ? DateTime.Parse("1900-01-01") : mydr.GetDateTime(index);

item.Age =GetAgeByBirthdate(item.birthday);

listBox1.Items.Add(item);
}



mydr.Close();

}

实在是抱歉...DateTime不是那样定义的... 可是楼下两位直接复制粘贴 也太没品了吧

直接在sql语句中处理，将日期转换成年龄 SELECT DATEDIFF(YEAR,'1990-01-01',GETDATE())；

你实体类再加一个字段 是年龄,然后取数据的时候,减一下现在的时间 不就好了吗

        public class Person
        {
            public String Name;
            public DateTime birthday;
            public Int32 Age;
        }        
        public List<Person> SelectPurchaseContractLog(String PurchasingMan)
        {
            List<Person> list = new List<Person>();

            String sql = @"......";
            command.CommandText = sql;
            command.Parameters.Add("purchasing_man", SqlDbType.NChar, 255).Value = PurchasingMan;

            using (SqlDataReader reader = command.ExecuteReader())
            {
                while (reader.Read())
                {
                    Person item = new Person();
                    int index = reader.GetOrdinal("name");
                    item.Name = reader.IsDBNull(index) ? String.Empty : reader.GetString(index);

                    index = reader.GetOrdinal("birthday");
                    item.birthday= reader.IsDBNull(index) ?  new DateTime(1900,1,1) : reader.GetDateTime(index);

                   
                    item.Age= DateTime.Now.Year - item.birthday.Year;
                    list.Add(item);
                }
            }
            return list;
        }

算实岁

select 
cast((DATEDIFF(day,出生日期,getdate())+DATEDIFF(day,出生日期,getdate())/365*0.25)/365
as int)

算虚岁

select 
celling((DATEDIFF(day,出生日期,getdate())+DATEDIFF(day,出生日期,getdate())/365*0.25)/365)

public class Person
        {
            public String Name;
            public DateTime birthday;
            public Int32 Age;
        }

        private void button1_Click(object sender, EventArgs e)
        {
            database db = new database();
            string sql = "select * from JZK_pat where times=1";
            SqlDataReader mydr;
            db.runsql(sql, out mydr);
            while (mydr.Read())
            {
                Person item = new Person();
                int index = mydr.GetOrdinal("birthday");
                item.birthday = mydr.IsDBNull(index) ? new DateTime("1900-01-01") : mydr.GetDateTime(index);
                item.Age = DateTime.Now.Year - item.birthday.Year;
                listBox1.Items.Add(item);
            }
            mydr.Close();  
        }

("1900-01-01")下面显示红色波浪线是为什么

public class Person
        {
            public String Name;
            public DateTime birthday;
            public Int32 Age;
        }

        private void button1_Click(object sender, EventArgs e)
        {
            database db = new database();
            string sql = "select * from JZK_pat where times=1";
            SqlDataReader mydr;
            db.runsql(sql, out mydr);
            while (mydr.Read())
            {
                Person item = new Person();
                int index = mydr.GetOrdinal("birthday");
                item.birthday = mydr.IsDBNull(index) ? new DateTime("1900-01-01") : mydr.GetDateTime(index);
                item.Age = DateTime.Now.Year - item.birthday.Year;
                listBox1.Items.Add(item);
            }
            mydr.Close();  
        }
//代码中("1900-01-01")下面显示为波浪线，不知道是什么原因，请大神指教一下，谢谢

代码中("1900-01-01")下面显示为红色波浪线，不知道是什么原因，请大神指教一下，谢谢

DateTime birthday = new DateTime(2012, 12,12);
DateTime now = DateTime.Now;
if(birthday > now)
{
    Console.WriteLine("出生日期要小于当前日期");
    return;
}
int year = now.Year - birthday.Year;
int month = now.Month - birthday.Month;
if(month < 0)
{
    year--;
    month += 12;           
}
int day = now.Day - birthday.Day;
if(day < 0)
{
    month--;
    if(month < 0)
    {
        year--;
        month = 11;
    }
    day += DateTime.DaysInMonth(now.Year, now.Month - 1);
}
 
Console.WriteLine("{0}年{1}月{2}天", year, month, day);

namespace ExDevilLee.DateTime
{
    /// <summary>
    /// 年龄计算工具类
    /// 由两个日期参数计算出精确年龄字符串
    /// </summary>
    public static class CalculateAgeCls
    {
        /// <summary>
        /// 获得年龄字符串：某个日期点到今天的年龄
        /// 默认返回：xx岁xx月xx天
        /// </summary>
        /// <param name="p_FirstDateTime">第1个日期参数</param>
        public static string GetAgeString(System.DateTime p_FirstDateTime)
        {
            return CalculateAgeString(p_FirstDateTime, System.DateTime.Now, null);
        }
        /// <summary>
        /// 获得年龄字符串：某个日期点到今天的年龄
        /// 默认返回：xx岁xx月xx天
        /// </summary>
        /// <param name="p_FirstDateTime">第1个日期参数</param>
        /// <param name="p_Format">返回字符串的格式，默认为：{0}岁{1}月{2}天</param>
        public static string GetAgeString(System.DateTime p_FirstDateTime, string p_ReturnFormat)
        {
            return CalculateAgeString(p_FirstDateTime, System.DateTime.Now, p_ReturnFormat);
        }
        /// <summary>
        /// 获得年龄字符串：两个日期点之间的年龄
        /// 默认返回：xx岁xx月xx天
        /// </summary>
        /// <param name="p_FirstDateTime">第1个日期参数</param>
        /// <param name="p_SecondDateTime">第2个日期参数</param>
        public static string GetAgeString(System.DateTime p_FirstDateTime, System.DateTime p_SecondDateTime)
        {
            return CalculateAgeString(p_FirstDateTime, p_SecondDateTime, null);
        }
        /// <summary>
        /// 获得年龄字符串：两个日期点之间的年龄
        /// 默认返回：xx岁xx月xx天
        /// </summary>
        /// <param name="p_FirstDateTime">第1个日期参数</param>
        /// <param name="p_SecondDateTime">第2个日期参数</param>
        /// <param name="p_Format">返回字符串的格式，默认为：{0}岁{1}月{2}天</param>
        public static string GetAgeString(System.DateTime p_FirstDateTime, System.DateTime p_SecondDateTime, string p_ReturnFormat)
        {
            return CalculateAgeString(p_FirstDateTime, p_SecondDateTime, p_ReturnFormat);
        }

        /// <summary>
        /// 计算年龄字符串
        /// 默认返回：xx岁xx月xx天
        /// </summary>
        /// <param name="p_FirstDateTime">第1个日期参数</param>
        /// <param name="p_SecondDateTime">第2个日期参数</param>
        /// <param name="p_Format">返回字符串的格式，默认为：{0}岁{1}月{2}天</param>
        private static string CalculateAgeString(System.DateTime p_FirstDateTime, System.DateTime p_SecondDateTime, string p_ReturnFormat)
        {
            //判断时间段是否为正。若为负，调换两个时间点的位置。
            if (System.DateTime.Compare(p_FirstDateTime, p_SecondDateTime) > 0)
            {
                System.DateTime stmpDateTime = p_FirstDateTime;
                p_FirstDateTime = p_SecondDateTime;
                p_SecondDateTime = stmpDateTime;
            }

            //判断返回字符串的格式。若为空，则给默认值：{0}岁{1}月{2}天
            if (string.IsNullOrEmpty(p_ReturnFormat)) p_ReturnFormat = "{0}岁{1}月{2}天";

            //定义：年、月、日
            int year, month, day;

            //计算：天
            day = p_SecondDateTime.Day - p_FirstDateTime.Day;
            if (day < 0)
            {
                day += System.DateTime.DaysInMonth(p_FirstDateTime.Year, p_FirstDateTime.Month);
                p_FirstDateTime = p_FirstDateTime.AddMonths(1);
            }
            //计算：月
            month = p_SecondDateTime.Month - p_FirstDateTime.Month;
            if (month < 0)
            {
                month += 12;
                p_FirstDateTime = p_FirstDateTime.AddYears(1);
            }
            //计算：年
            year = p_SecondDateTime.Year - p_FirstDateTime.Year;

            //返回格式化后的结果
            return string.Format(p_ReturnFormat, year, month, day);
        }
    }
}

1、已知一个日期点，求该日期到当前日期（今天）的精确年龄；

2、已知两个日期点，求这两个日期点的精确年龄；