Question

I have dates in a column of database but the date format is not same. Some are mm-dd-yyyy and some are mm.dd.yy or other. How do I format it into same type using a query?

I am using SQL Server 2008.

Answer 1

My recommendation would be:

1. Add a column of type DATE to your table:

   ALTER TABLE dbo.YourTable ADD NewDateColumn DATE
   

2. Update your table to convert those varchar values to DATE:

   UPDATE dbo.YourTable
   SET NewDateColumn = CAST(YourOldColumn AS DATE)
   WHERE NewDateColumn IS NULL AND ISDATE(YourOldColumn) = 1
   

3. Drop that old column:

   ALTER TABLE dbo.YourTable DROP COLUMN YourOldColumn
   

From now on – use the new DATE column exclusively.

You can format it to any string representation that is supported in SQL Server using the CONVERT function

Once you have that DATE column, you can output it in whatever string formatting you need:

SELECT
   CONVERT(VARCHAR(20), GETDATE(), 101) 'US format', 
   CONVERT(VARCHAR(20), GETDATE(), 102) 'ANSI format', 
   CONVERT(VARCHAR(20), GETDATE(), 104) 'German format'

gives you:

US format   ANSI format German format
12/29/2011  2011.12.29  29.12.2011