Question

I am trying to insert a unique value into my table, however I need to know the ID before I create it. I know an AUTO_INCREMENT would have solved this problem, but this field is not AUTO_INCREMENTed.

This is my code…

INSERT INTO networks 
    (NETWORK_ID, ADMIN_USER_ID, NETWORK_NAME, ADDRESS)
VALUES 
    ((SELECT MAX(NETWORK_ID)+1 FROM networks) , 3, 'Arcafe', 'habarzel 2 TA')

When I run it, I get a warning that I can’t use the table in the FROM, I guess because it is pointing to itself. How can I achieve what I need? Can I change a field into an AUTO_INCREMENT field?

Answer 1

Usually you set the field to be an auto increment field when it is defined. To do so afterwards, you can use:

ALTER TABLE networks MODIFY NETWORK_ID int(10) unsigned NOT NULL auto_increment;

To then insert an ew record and for it to automatically get an assigned ID, merely omit the field from the insert, eg.

INSERT INTO networks 
    (ADMIN_USER_ID, NETWORK_NAME, ADDRESS)
VALUES 
    (3, 'Arcafe', 'habarzel 2 TA')