MYSQL: How can I create a new row and get the new id without inserting data?

Question

Normally I get a new ID by inserting some data and it creates a new row and returns the new ID. But if I dont want to insert any data I just want to create a new row with a new ID and get the new ID...how can I do that?

Thanks.

UPDATE:

OK Here is my issue. The table I wanted to do this to only has the 1 ID column. Why? I'll explain (we'll I'll try to). I have another table where each row has its own unique ID variation_id (auto-inc), but each row needs to be tied to a group of other rows from the same table. I have another column called group_id I can't have it auto-inc because it needs to appear multiple times, it his what says which variations should be grouped together. So I wanted to have a second table with group_id as the primary key and auto-inc so I could use that to generate the new group_id whenever I need a new group. I guess I am going about this the wrong way....so what should I do?

Answer 1

here is an example:

CREATE TABLE X (id int PRIMARY KEY AUTO_INCREMENT);

then you can "feed" your table with:

INSERT INTO X (id) VALUES (NULL);
SELECT LAST_INSERT_ID();

Check this fiddle: http://sqlfiddle.com/#!2/6b19c/1

Hope it helps!

Тарас Лукавий did another question and here's the answer:

CREATE TABLE X (id int PRIMARY KEY AUTO_INCREMENT, time timestamp);

then you "feed" data with:

INSERT INTO X (id, time) VALUES (NULL, now());
SELECT LAST_INSERT_ID();

Now, let's check it:

SELECT * FROM X

You'll see every row with automatic id and timestamp.

Check this fiddle: http://sqlfiddle.com/#!2/9a344/2

Hope it helps!

Answer 2

All your columns would have to be nullable, and you'd have to insert null for all the other columns but ID.