Custom Date/Time formatting in SQL Server

Question

I am trying to write a stored procedure which selects columns from a table and adds 2 extra columns to the ResultSet. These 2 extra columns are the result of conversions on a field in the table which is a Datetime field.

The Datetime format field has the following format 'YYYY-MM-DD HH:MM:SS.S'

The 2 additional fields which should be in the following format:

1. DDMMM
2. HHMMT, where T is 'A' for a.m. and 'P' for p.m.

Example: If the data in the field was '2008-10-12 13:19:12.0' then the extracted fields should contain:

1. 12OCT
2. 0119P

I have tried using CONVERT string formats, but none of the formats match the output I want to get. I am thinking along the lines of extracting the field data via CONVERT and then using REPLACE, but I surely need some help here, as I am no sure.

Could anyone well versed in stored procedures help me out here? Thanks!

Answer 1

If dt is your datetime column, then

For 1:

SUBSTRING(CONVERT(varchar, dt, 13), 1, 2)
    + UPPER(SUBSTRING(CONVERT(varchar, dt, 13), 4, 3))

For 2:

SUBSTRING(CONVERT(varchar, dt, 100), 13, 2)
    + SUBSTRING(CONVERT(varchar, dt, 100), 16, 3)

Answer 2

You can use the following command in SQL server to make it:

select FORMAT(getdate(), N'yyyy-MM-ddThh:mm:ss')

Answer 3

If it's something more specific like DateKey (yyyymmdd) that you need for dimensional models, I suggest something without any casts/converts:

DECLARE @DateKeyToday int = (SELECT 10000 * DATEPART(yy,GETDATE()) + 100 * DATEPART(mm,GETDATE()) + DATEPART(dd,GETDATE()));
PRINT @DateKeyToday

Answer 4

The Datetime format field has the following format 'YYYY-MM-DD HH:MM:SS.S'

That statement is false. That's just how Enterprise Manager or SQL Server chooses to show the date. Internally it's a 8-byte binary value, which is why some of the functions posted by Andrew will work so well.

Kibbee makes a valid point as well, and in a perfect world I would agree with him. However, sometimes you want to bind query results directly to display control or widgets and there's really not a chance to do any formatting. And sometimes the presentation layer lives on a web server that's even busier than the database. With those in mind, it's not necessarily a bad thing to know how to do this in SQL.