Question

I have a SQL table that has a primary key (Row_id) that has a format like:

110001  
110002  
110003  
...  

This table may be updated by removing some rows over time. I have a php script and want to have it insert new rows to first available position not just to increase the last existing id.

for example if I have this:

110001  
110002  
110004  
110005

I want to new row be inserted and given the id = 110003 not 110006.

any help would be appreciated!

Answer 1

Don’t know why you want to reuse id(s) but, here we go

Suppose that you’re table name is Tbl:

Select MIN(a.Id + 1)
From   Tbl A 
       Left Join Tbl B
         On A.Id = B.Id - 1
Where  B.Id Is NULL

this should works for retrieve the id that you want.
After that, obviously, you have to do an insert based on the previous value.
So

INSERT into yourTable(id,....) VALUES(
    Select MIN(a.Id + 1)
    From   Tbl A 
           Left Join Tbl B
             On A.Id = B.Id - 1
    Where  B.Id Is NULL,
    .....)