There is a nice blog about this problem by Plamen Ratchev but I was unable to quickly find it. For now take a look at this thread:

https://social.technet.microsoft.com/Forums/en-US/075b24ea-f1dc-4743-990f-4d818b540b6d/sql-help-finding-gaps-in-dates

>Sir I have this data (MS SQLSERVER 2008 TABLE)
>
>

>CREATE CURSOR junk(date t,sno n(3))
>SET DATE YMD
>SET CENTURY on
>
>INSERT INTO junk values({^2019-01-01 01:11:28.000},0)
>INSERT INTO junk values({^2019-01-01 03:21:23.000},0)
>INSERT INTO junk values({^2019-01-02 05:31:22.000},0)
>INSERT INTO junk values({^2019-01-02 15:41:27.000},0)
>INSERT INTO junk values({^2019-01-04 17:51:29.000},0)
>INSERT INTO junk values({^2019-01-04 21:51:19.000},0)
>INSERT INTO junk values({^2019-01-05 02:31:36.000},0)
>INSERT INTO junk values({^2019-01-08 05:21:48.000},0)
>INSERT INTO junk values({^2019-01-08 00:31:59.000},0)
>INSERT INTO junk values({^2019-01-08 18:41:35.000},0)
>INSERT INTO junk values({^2019-01-09 10:11:11.000},0)
>brow
>

>
>I want to UPDATE sno column like this
>
>
>
>Sno changes when date sequence is changed.
>No changes in previous sno if date is going in sequence (no missed date)
>
>Please