Thursday, 28 May 2015

Interview Question - What is Identity column and Can we update it ?

This question was fielded in the recent job interview that my colleague was part of. He is moving on and I am glad that he is .. not that I hate him but his skills are underutilized here...

Back to the question  .. What is the Identity column in SQL server and Can we update the Identity column value ?

We all know what Identity column is ... in case you don't then 

According to Wikipedia

In short -  Identity column is an auto increment column. 

Now back to practical part of the question - Can we update the Identity column value ?

Let us Try ..


As we can see Id column values got Auto filled in.

Now, let us try to update it..

UPDATE #tbl_Identity SET Id 5


Boom...........We got an Error

This tells us that Identity column value cannot be updated.  But what if you really wanna do it.. Is there any way ? If it is @ the top of your head then let me know or stay tuned for next blog entry to find out the answer

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