support autoIncColumnChange

[feitianbubu]

No description provided.

[a8m]

Thanks for the contribution, @feitianbubu.

The AUTO_INCREMENT clause is a table attribute (not a column attribute) and it’s already implemented here: https://github.com/ariga/atlas/blob/master/sql/mysql/diff.go#L394. Do you have any issues with it?

[feitianbubu]

Thank you for your reply. @a8m
The autoIncChange func only effect where the autoincrement value is modified. However, when the user adds or removes the autoincrement attribute on a field, it does not take effect. The autoIncColumnChange I added will solves this issue.

example, when user change a AUTO_INCREMENT on id filed

`CREATE TABLE `account` (
  `id` bigint NOT NULL AUTO_INCREMENT,  // will not be change
  PRIMARY KEY (`id`)
) AUTO_INCREMENT=2;` //  will change by autoIncChange

[a8m]

Thanks for the response, @feitianbubu. Can you please describe the use case with "before" and "after" schemas? Do you try to add it to an existing column? Note that adding the AUTO_INCREMENT to a table without adding it to a column is ignored.

[feitianbubu]

Thanks for the response, @a8m ,
This is a example:

1. before hcl:

table "account" {
  schema = schema.test
  column "id" {
    null = false
    type = bigint
  }
  primary_key {
    columns = [column.id]
  }
}

2. after hcl:

table "account" {
  schema = schema.test
  column "id" {
    null           = false
    type           = bigint
    auto_increment = true
  }
  primary_key {
    columns = [column.id]
  }
}

3. current atlas schema diff result:
   Schemas are synced, no changes to be made.
4. need result:

-- Modify "account" table
ALTER TABLE `account` MODIFY COLUMN `id` bigint NOT NULL AUTO_INCREMENT;

[feitianbubu]

current atlas schema diff result:
Schemas are synced, no changes to be made.

commit pr will gen:

-- Modify "account" table
ALTER TABLE `account` MODIFY COLUMN `id` bigint NOT NULL AUTO_INCREMENT;