MySQL incrementing value

Question

Is there a way to make a value increment with every insert if having multiple inserts? (I dont speak of the primary key that autoincrements)

Lets say I have a struct

Answer 1

Yes: Use a user defined variable:

SET @position := 0; -- Define a variable
INSERT INTO products
SELECT id_product, id_category, name, (@position := @position + 1)
FROM db2.products
WHERE id_category = xxx;

The result of increment to @position is the value used for the insert.

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Edit:

You can skip the declaration of the variable by handling the initial value in-line:

...
SELECT ..., (@position := ifnull(@position, 0) + 1)
...

This can be particularly handy when executing the query using a driver that does not allow multiple commands (separated by semicolons).