SQL语句中将Datetime类型转换为字符串类型

 

0	Feb 22 2006 4:26PM	CONVERT(CHAR(19), CURRENT_TIMESTAMP, 0)
1	02/22/06	CONVERT(CHAR(8), CURRENT_TIMESTAMP, 1)
2	06.02.22	CONVERT(CHAR(8), CURRENT_TIMESTAMP, 2)
3	22/02/06	CONVERT(CHAR(8), CURRENT_TIMESTAMP, 3)
4	22.02.06	CONVERT(CHAR(8), CURRENT_TIMESTAMP, 4)
5	22-02-06	CONVERT(CHAR(8), CURRENT_TIMESTAMP, 5)
6	22 Feb 06	CONVERT(CHAR(9), CURRENT_TIMESTAMP, 6)
7	Feb 22, 06	CONVERT(CHAR(10), CURRENT_TIMESTAMP, 7)
8	16:26:08	CONVERT(CHAR(8), CURRENT_TIMESTAMP, 8)
9	Feb 22 2006 4:26:08:020PM	CONVERT(CHAR(26), CURRENT_TIMESTAMP, 9)
10	02-22-06	CONVERT(CHAR(8), CURRENT_TIMESTAMP, 10)
11	06/02/22	CONVERT(CHAR(8), CURRENT_TIMESTAMP, 11)
12	060222	CONVERT(CHAR(6), CURRENT_TIMESTAMP, 12)
13	22 Feb 2006 16:26:08:020	CONVERT(CHAR(24), CURRENT_TIMESTAMP, 13)
14	16:26:08:037	CONVERT(CHAR(12), CURRENT_TIMESTAMP, 14)
20	2006-02-22 16:26:08	CONVERT(CHAR(19), CURRENT_TIMESTAMP, 20)
21	2006-02-22 16:26:08.037	CONVERT(CHAR(23), CURRENT_TIMESTAMP, 21)
22	02/22/06 4:26:08 PM	CONVERT(CHAR(20), CURRENT_TIMESTAMP, 22)
23	2006-02-22	CONVERT(CHAR(10), CURRENT_TIMESTAMP, 23)
24	16:26:08	CONVERT(CHAR(8), CURRENT_TIMESTAMP, 24)
25	2006-02-22 16:26:08.037	CONVERT(CHAR(23), CURRENT_TIMESTAMP, 25)
100	Feb 22 2006 4:26PM	CONVERT(CHAR(19), CURRENT_TIMESTAMP, 100)
101	02/22/2006	CONVERT(CHAR(10), CURRENT_TIMESTAMP, 101)
102	2006.02.22	CONVERT(CHAR(10), CURRENT_TIMESTAMP, 102)
103	22/02/2006	CONVERT(CHAR(10), CURRENT_TIMESTAMP, 103)
104	22.02.2006	CONVERT(CHAR(10), CURRENT_TIMESTAMP, 104)
105	22-02-2006	CONVERT(CHAR(10), CURRENT_TIMESTAMP, 105)
106	22 Feb 2006	CONVERT(CHAR(11), CURRENT_TIMESTAMP, 106)
107	Feb 22, 2006	CONVERT(CHAR(12), CURRENT_TIMESTAMP, 107)
108	16:26:08	CONVERT(CHAR(8), CURRENT_TIMESTAMP, 108)
109	Feb 22 2006 4:26:08:067PM	CONVERT(CHAR(26), CURRENT_TIMESTAMP, 109)
110	02-22-2006	CONVERT(CHAR(10), CURRENT_TIMESTAMP, 110)
111	2006/02/22	CONVERT(CHAR(10), CURRENT_TIMESTAMP, 111)
112	20060222	CONVERT(CHAR(8), CURRENT_TIMESTAMP, 112)
113	22 Feb 2006 16:26:08:067	CONVERT(CHAR(24), CURRENT_TIMESTAMP, 113)
114	16:26:08:067	CONVERT(CHAR(12), CURRENT_TIMESTAMP, 114)
120	2006-02-22 16:26:08	CONVERT(CHAR(19), CURRENT_TIMESTAMP, 120)
121	2006-02-22 16:26:08.080	CONVERT(CHAR(23), CURRENT_TIMESTAMP, 121)
126	2006-02-22T16:26:08.080	CONVERT(CHAR(23), CURRENT_TIMESTAMP, 126)
127	2006-02-22T16:26:08.080	CONVERT(CHAR(23), CURRENT_TIMESTAMP, 127)
130	24 ???? 1427 4:26:08:080PM	CONVERT(CHAR(32), CURRENT_TIMESTAMP, 130)
131	24/01/1427 4:26:08:080PM	CONVERT(CHAR(25), CURRENT_TIMESTAMP, 131)

如数据：

MonitorTime
2012-05-05 00:00:00.000
2012-05-05 16:00:00.000
2012-05-05 17:00:00.000
2012-05-05 18:00:00.000
2012-05-05 19:00:00.000

select CONVERT(CHAR(19), MonitorTime, 120) from t_metData  

执行结果：

(无列名)
2012-05-05 00:00:00
2012-05-05 16:00:00
2012-05-05 17:00:00

我们在处理字符串日期格式常用DateTime.Pares() 但是这个形式的转换是相当有限的，有些C#是会不懂你写入的日期格式的如20031231。那么类似 "20100101" 或者其它形式的字符串如何转换成日期型呢?

一、拼接字符串的形式 

DateTime dt=Convert.ToDateTime("20100101".Substring(0,4)+"-"+"20100101".Substring(4,2)+"-"+"20071107".Substring(6,2));  

二、Convert.ToDateTime(string)

string格式有要求，必须是yyyy-MM-dd hh:mm:ss 

三、Convert.ToDateTime(string, IFormatProvider)

DateTime dt;

DateTimeFormatInfo dtFormat = new System.GlobalizationDateTimeFormatInfo();

dtFormat.ShortDatePattern = "yyyy/MM/dd";

dt = Convert.ToDateTime("2011/05/26", dtFormat);

四、DateTime.ParseExact()

string dateString = "20110526";

DateTime dt = DateTime.ParseExact(dateString, "yyyyMMdd", System.Globalization.CultureInfo.CurrentCulture);

//或者

DateTime dt = DateTime.ParseExact(dateString, "yyyyMMdd", System.Globalization.CultureInfo.InvariantCulture);

五、DateTime.TryParse(string,out datetime)

1、更多时候，会采用DateTime.TryParse(string,out datetime)方法，因为此方法有安全机制，当string内容不正确时，可以返回日期的最小值MinValue。并且可以通过返回的bool值判断转化是否成功。而DateTime.ParseExact()需要按特定的格式来转换，对格式的要求比较严，如果string中不是日期内容，而量类似“asdfasd”的字符串，则会出错。

2、用DateTime.TryParse(string,out datetime)转换后，得到的datetime可以用 datetime.ToString("ddd, MMM. dd")来转换为特殊需求的格式，比较灵活方便。