mysql - How to insert the number of id in the neighbor column? -

i have table structure:

+----+-------------------+ | id | identical_with_id | +----+-------------------+ 

id auto-increment , need insert in column identical_with_id identical value id's value. how can that?

i want this:

+----+-------------------+ | id | identical_with_id | +----+-------------------+ | 1  | 1                 | | 2  | 2                 | | 3  | 3                 | +----+-------------------+ 

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note, in reality table containing other values identical_with_id column, this:

+----+-------------------+ | id | identical_with_id | +----+-------------------+ | 1  | 1                 |    -- question | 2  | 1                 |    -- answer of above question | 3  | 1                 |    -- answer of above question | 4  | 4                 |    -- question | 5  | 4                 |    -- answer of above question | 6  | 6                 |    -- question | 7  | 7                 |    -- question | 8  | 7                 |    -- answer of above question | 9  | 7                 |    -- answer of above question +----+-------------------+ 

now need insert question in table. , want know how can fill column: identical_with_id ?

no need update table. can in single insert query shown below.

insert `table_name` values(null, (select `auto_increment`  information_schema.tables table_schema = 'database_name' , table_name = 'table_name')); 

although don't see point of doing so...