The CONVERT() function allows you to convert between data types. It’s similar to the CAST() function, but one of the benefits of CONVERT() is that, when you convert from a date/time data type to a string, you can add an optional argument that specifies the style that you want the return value to be in. For example, you can have it returned as dd.mm.yyyy, yyyy-mm-dd, dd mon yyyy, etc
This article contains examples of the various styles you can return when converting a date/time value to a string using the CONVERT() function in SQL Server.
Basic Example
The default style when converting from the datetime and smalldatetime data types is 0 and 100 (these represent the same style). Therefore, when you don’t provide a style (third parameter), this is how it’s styled:
DECLARE @date datetime = GETDATE();
SELECT
@date AS Original,
CONVERT(varchar, @date) AS Converted;
Result:
+-------------------------+---------------------+ | Original | Converted | |-------------------------+---------------------| | 2018-06-07 03:08:21.997 | Jun 7 2018 3:08AM | +-------------------------+---------------------+
However, you’ll get a different result if the original data type is not datetime or smalldatetime.
If you need it to be returned in a different style, you’ll need to specify a third argument.
Styles with Two Digit Years
Below are examples of the various values you can use to specify the style using a two digit year component.
Styles 1 to 6
DECLARE @date datetime2 = '2018-06-07';
SELECT
CONVERT(nvarchar(30), @date, 1) AS '1',
CONVERT(nvarchar(30), @date, 2) AS '2',
CONVERT(nvarchar(30), @date, 3) AS '3',
CONVERT(nvarchar(30), @date, 4) AS '4',
CONVERT(nvarchar(30), @date, 5) AS '5',
CONVERT(nvarchar(30), @date, 6) AS '6';
Result:
+----------+----------+----------+----------+----------+-----------+ | 1 | 2 | 3 | 4 | 5 | 6 | |----------+----------+----------+----------+----------+-----------| | 06/07/18 | 18.06.07 | 07/06/18 | 07.06.18 | 07-06-18 | 07 Jun 18 | +----------+----------+----------+----------+----------+-----------+
Styles 7 to 6
DECLARE @date datetime2 = '2018-06-07';
SELECT
CONVERT(nvarchar(30), @date, 7) AS '7',
CONVERT(nvarchar(30), @date, 8) AS '8',
CONVERT(nvarchar(30), @date, 10) AS '10',
CONVERT(nvarchar(30), @date, 11) AS '11',
CONVERT(nvarchar(30), @date, 12) AS '12',
CONVERT(nvarchar(30), @date, 14) AS '14';
Result:
+------------+----------+----------+----------+--------+------------------+ | 7 | 8 | 10 | 11 | 12 | 14 | |------------+----------+----------+----------+--------+------------------| | Jun 07, 18 | 00:00:00 | 06-07-18 | 18/06/07 | 180607 | 00:00:00.0000000 | +------------+----------+----------+----------+--------+------------------+
Styles with Four Digit Years
Below are examples of the various values you can use to specify the style using a four digit year component.
Styles 100 to 103
DECLARE @date datetime2 = '2018-06-07 02:35:52.8537677';
SELECT
CONVERT(nvarchar(30), @date, 100) AS '100',
CONVERT(nvarchar(30), @date, 101) AS '101',
CONVERT(nvarchar(30), @date, 102) AS '102',
CONVERT(nvarchar(30), @date, 103) AS '103';
Result:
+---------------------+------------+------------+------------+ | 100 | 101 | 102 | 103 | |---------------------+------------+------------+------------| | Jun 7 2018 2:35AM | 06/07/2018 | 2018.06.07 | 07/06/2018 | +---------------------+------------+------------+------------+
Styles 104 to 108
DECLARE @date datetime2 = '2018-06-07 02:35:52.8537677';
SELECT
CONVERT(nvarchar(30), @date, 104) AS '104',
CONVERT(nvarchar(30), @date, 105) AS '105',
CONVERT(nvarchar(30), @date, 106) AS '106',
CONVERT(nvarchar(30), @date, 107) AS '107',
CONVERT(nvarchar(30), @date, 108) AS '108';
Result:
+------------+------------+-------------+--------------+----------+ | 104 | 105 | 106 | 107 | 108 | |------------+------------+-------------+--------------+----------| | 07.06.2018 | 07-06-2018 | 07 Jun 2018 | Jun 07, 2018 | 02:35:52 | +------------+------------+-------------+--------------+----------+
Styles 109 to 112
DECLARE @date datetime2 = '2018-06-07 02:35:52.8537677';
SELECT
CONVERT(nvarchar(30), @date, 109) AS '109',
CONVERT(nvarchar(30), @date, 110) AS '110',
CONVERT(nvarchar(30), @date, 111) AS '111',
CONVERT(nvarchar(30), @date, 112) AS '112';
Result:
+--------------------------------+------------+------------+----------+ | 109 | 110 | 111 | 112 | |--------------------------------+------------+------------+----------| | Jun 7 2018 2:35:52.8537677AM | 06-07-2018 | 2018/06/07 | 20180607 | +--------------------------------+------------+------------+----------+
Styles 113 to 114
DECLARE @date datetime2 = '2018-06-07 02:35:52.8537677';
SELECT
CONVERT(nvarchar(30), @date, 113) AS '113',
CONVERT(nvarchar(30), @date, 114) AS '114';
Result:
+------------------------------+------------------+ | 113 | 114 | |------------------------------+------------------| | 07 Jun 2018 02:35:52.8537677 | 02:35:52.8537677 | +------------------------------+------------------+
Styles 120 to 127
DECLARE @date datetime2 = '2018-06-07';
SELECT
CONVERT(nvarchar(30), @date, 120) AS '120',
CONVERT(nvarchar(30), @date, 126) AS '126',
CONVERT(nvarchar(30), @date, 127) AS '127';
Result:
+---------------------+---------------------+---------------------+ | 120 | 126 | 127 | |---------------------+---------------------+---------------------| | 2018-06-07 00:00:00 | 2018-06-07T00:00:00 | 2018-06-07T00:00:00 | +---------------------+---------------------+---------------------+
Style 130
DECLARE @date datetime2 = '2018-06-07';
SELECT
CONVERT(nvarchar(30), @date, 130) AS '130';
Result:
+--------------------------------+ | 130 | |--------------------------------| | 24 رمضان 1439 12:00:00.0000000 | +--------------------------------+
Microsoft warns that this value does not render correctly on a default US installation of SSMS.
Style 131
DECLARE @date datetime2 = '2018-06-07';
SELECT
CONVERT(nvarchar(30), @date, 131) AS '131';
Result:
+-------------------------------+ | 131 | |-------------------------------| | 24/09/1439 12:00:00.0000000AM | +-------------------------------+
You can read more about the available date/time styles on the Microsoft website.