Question

I am trying to change the date format of a column, the column is set as varchar column name date time. The problem is that i cannot actually change the data type because the data is automatically inputted by a PLC on the automation side. I need the date in a date or numeric value because when i run my queries i need to give the system a date range. I am trying to use substrings to work around this issue but am getting an error saying that the data type is out of range. here is the syntax of my query.

select cast(
     (substring(datetime, 1, 4) + '-' +
      SUBSTRING(DateTime, 5, 2) + '-' + 
      SUBSTRING(DateTime, 7, 2) + ' ' + '00:00:00.000') as dateTime) as "Date"
    , ID1
    , ID2
    ,  diameter
    , WeightTheoretical
    , WeightActual
    , StockType 
from table1 
where datetime is not null 
    and datetime <> '' 
    and datetime <> '0' 
order by "Date", ID1;

Edit- the date format is as such 20120622:00:00:00:000

Answer 1

It looks from your SQL that your date string is of the format YYYYMMDD

This should convert fine using either the CAST or CONVERT functions:

eg

SELECT CONVERT(datetime,'20120601')
SELECT CAST('20120601' as datetime)

both return the expected value as a datetime.

EDIT: Based on the supplied format you specified, I’d use the SubString to chop the supplied data down a bit:

eg

SELECT CONVERT(datetime,SUBSTRING('20120601',1,8))