How to capture the error message?

Is possible to capture the message of error generated in the execution
of a command SQL?
Thanks.DECLARE@.Error

..sql statement

SELECT @.Error = @.@.ERROR

SELECT *
FROM master..sysmessages
WHERE error = @.Error|||I thank its reply, but I want to capture the specific message of the error and not it generic message. For example:

"Cannot insert the value NULL into column 'field1', table 'DB.dbo.Tab'; column does not allow nulls. INSERT fails."

instead of :

"Cannot insert the value NULL into column '%.*ls', table '%.*ls'; column does not allow nulls. %ls fails."

DECLARE@.Error

..sql statement

SELECT @.Error = @.@.ERROR

SELECT *
FROM master..sysmessages
WHERE error = @.Error