sql 中convert的用法
select CONVERT(varchar(10),birthday,120) from abc
CONVERT() 函数是把日期转换为新数据类型的通用函数。
CONVERT() 函数可以用不同的格式显示日期/时间数据。
语法
CONVERT(data_type(length),data_to_be_converted,style)
data_type(length) 规定目标数据类型（带有可选的长度）。
data_to_be_converted 含有需要转换的值。
style 规定日期/时间的输出格式。
Style(2位表示年份) | Style(4位表示年份) | 输入输出格式 
------------------------------------------------------------------------------------------------------------0 | 100 | mon dd yyyy hh:miAM(或PM) ------------------------------------------------------------------------------------------------------------1 | 101 美国 | mm/dd/yy ------------------------------------------------------------------------------------------------------------2 | 102 ANSI | yy-mm-dd ------------------------------------------------------------------------------------------------------------3 | 103 英法 | dd/mm/yy ------------------------------------------------------------------------------------------------------------4 | 104 德国 | dd.mm.yy ------------------------------------------------------------------------------------------------------------5 | 105 意大利 | dd-mm-yy ------------------------------------------------------------------------------------------------------------6 | 106 | dd mon yy ------------------------------------------------------------------------------------------------------------7 | 107 | mon dd,yy ------------------------------------------------------------------------------------------------------------8 | 108 | hh:mm:ss ------------------------------------------------------------------------------------------------------------9 | 109 | mon dd yyyy hh:mi:ss:mmmmAM(或PM)------------------------------------------------------------------------------------------------------------10 | 110 美国 | mm-dd-yy ------------------------------------------------------------------------------------------------------------11 | 111 日本 | yy/mm/dd ------------------------------------------------------------------------------------------------------------12 | 112 ISO | yymmdd ------------------------------------------------------------------------------------------------------------13 | 113 欧洲默认值 | dd mon yyyy hh:mi:ss:mmm(24小时制) ------------------------------------------------------------------------------------------------------------14 | 114 | hh:mi:ss:mmm(24小时制) ------------------------------------------------------------------------------------------------------------20 | 120 ODBC 规范 | yyyy-mm-dd hh:mi:ss(24小时制) ------------------------------------------------------------------------------------------------------------21 | 121 | yyyy-mm-dd hh:mi:ss:mmm(24小时制) ------------------------------------------------------------------------------------------------------------
语句及查询结果：
SELECT
CONVERT
(
varchar
(
100
),
GETDATE
(),
0
):
05
16
2006
10
:57AM
SELECT
CONVERT
(
varchar
(
100
),
GETDATE
(),
1
):
05
/
16
/
06
SELECT
CONVERT
(
varchar
(
100
),
GETDATE
(),
2
):
06.05
.
16
SELECT
CONVERT
(
varchar
(
100
),
GETDATE
(),
3
):
16
/
05
/
06
SELECT
CONVERT
(
varchar
(
100
),
GETDATE
(),
4
):
16.05
.
06
SELECT
CONVERT
(
varchar
(
100
),
GETDATE
(),
5
):
16
-
05
-
06
SELECT
CONVERT
(
varchar
(
100
),
GETDATE
(),
6
):
16
05
06
SELECT
CONVERT
(
varchar
(
100
),
GETDATE
(),
7
):
05
16
,
06
SELECT
CONVERT
(
varchar
(
100
),
GETDATE
(),
8
):
10
:
57
:
46
SELECT
CONVERT
(
varchar
(
100
),
GETDATE
(),
9
):
05
16
2006
10
:
57
:
46
:827AM
SELECT
CONVERT
(
varchar
(
100
),
GETDATE
(),
10
):
05
-
16
-
06
SELECT
CONVERT
(
varchar
(
100
),
GETDATE
(),
11
):
06
/
05
/
16
SELECT
CONVERT
(
varchar
(
100
),
GETDATE
(),
12
):
060516
SELECT
CONVERT
(
varchar
(
100
),
GETDATE
(),
13
):
16
05
2006
10
:
57
:
46
:
937
SELECT
CONVERT
(
varchar
(
100
),
GETDATE
(),
14
):
10
:
57
:
46
:
967
SELECT
CONVERT
(
varchar
(
100
),
GETDATE
(),
20
):
2006
-
05
-
16
10
:
57
:
47
SELECT
CONVERT
(
varchar
(
100
),
GETDATE
(),
21
):
2006
-
05
-
16
10
:
57
:
47.157
SELECT
CONVERT
(
varchar
(
100
),
GETDATE
(),
22
):
05
/
16
/
06
10
:
57
:
47
AM
SELECT
CONVERT
(
varchar
(
100
),
GETDATE
(),
23
):
2006
-
05
-
16
SELECT
CONVERT
(
varchar
(
100
),
GETDATE
(),
24
):
10
:
57
:
47
SELECT
CONVERT
(
varchar
(
100
),
GETDATE
(),
25
):
2006
-
05
-
16
10
:
57
:
47.250
SELECT
CONVERT
(
varchar
(
100
),
GETDATE
(),
100
):
05
16
2006
10
:57AM
SELECT
CONVERT
(
varchar
(
100
),
GETDATE
(),
101
):
05
/
16
/
2006
SELECT
CONVERT
(
varchar
(
100
),
GETDATE
(),
102
):
2006.05
.
16
SELECT
CONVERT
(
varchar
(
100
),
GETDATE
(),
103
):
16
/
05
/
2006
SELECT
CONVERT
(
varchar
(
100
),
GETDATE
(),
104
):
16.05
.
2006
SELECT
CONVERT
(
varchar
(
100
),
GETDATE
(),
105
):
16
-
05
-
2006
SELECT
CONVERT
(
varchar
(
100
),
GETDATE
(),
106
):
16
05
2006
SELECT
CONVERT
(
varchar
(
100
),
GETDATE
(),
107
):
05
16
,
2006
SELECT
CONVERT
(
varchar
(
100
),
GETDATE
(),
108
):
10
:
57
:
49
SELECT
CONVERT
(
varchar
(
100
),
GETDATE
(),
109
):
05
16
2006
10
:
57
:
49
:437AM
SELECT
CONVERT
(
varchar
(
100
),
GETDATE
(),
110
):
05
-
16
-
2006
SELECT
CONVERT
(
varchar
(
100
),
GETDATE
(),
111
):
2006
/
05
/
16
SELECT
CONVERT
(
varchar
(
100
),
GETDATE
(),
112
):
20060516
SELECT
CONVERT
(
varchar
(
100
),
GETDATE
(),
113
):
16
05
2006
10
:
57
:
49
:
513
SELECT
CONVERT
(
varchar
(
100
),
GETDATE
(),
114
):
10
:
57
:
49
:
547
SELECT
CONVERT
(
varchar
(
100
),
GETDATE
(),
120
):
2006
-
05
-
16
10
:
57
:
49
SELECT CONVERT(varchar(100), GETDATE(), 121): 2006-05-16 10:57:49:000
select * from mk a where convert(varchar(10),rq,120)=(select convert(varchar(10),max(rq),120) from mk)