Question

I have a varchar column which contains date in following format

dd/mm/yyyy

I need to convert the column’s datatype to DATE. I’m using the following query

alter table [tblDocumentRevision]
alter column [RevisionDate] date  null

but I get an error

Msg 241, Level 16, State 1, Line 1
Conversion failed when converting date and/or time from character string.
The statement has been terminated.

I’m sure that all the values are in dd/mm/yyyy format. So why is it giving me the error?

Then I added a new column and tried

UPDATE [tblDocumentRevision]
SET NewDate = convert(date,[RevisionDate],103)
WHERE ISDATE([RevisionDate]) = 1

The check for ISDATE() = 1 should filter out those entries that cannot be converted to a DATE.

Then NewDate column has only the values where month and date are both less than or equal to 12 others are null. So I’m clearly seeing a issue with the dd/mm/yyyy format

Can someone please help me to solve this issue?

Answer 1

I used Google to find this. Try setting the format being running ALTER COLUMN.

EDIT

CREATE TABLE #tmpTest
(
  MyCol VARCHAR(20)
);

INSERT INTO #tmpTest(MyCol)
  VALUES('31/12/99');

ALTER TABLE #tmpTest ALTER COLUMN MyCol DATE;

Yields:

Msg 241, Level 16, State 1, Line 9
Conversion failed when converting date and/or time from character string.
The statement has been terminated.

Whereas:

CREATE TABLE #tmpTest
(
  MyCol VARCHAR(20)
);

INSERT INTO #tmpTest(MyCol)
  VALUES('31/12/99');

SET DATEFORMAT DMY;

ALTER TABLE #tmpTest ALTER COLUMN MyCol DATE;

Yields:

(1 row(s) affected)