Add not_ai tag

[nobokoba]

If primarykey is an integer , will be removed also have been included in the structure , I want to directly INSERT an integer value . Use for example, INSERT to a dependent table .

usage:

CREATE TABLE `user` (
  `user_id` int(11) NOT NULL AUTO_INCREMENT,
  `username` varchar(64) NOT NULL,
)
CREATE TABLE `user_setting` (
  `user_id` int(11) NOT NULL,
  `some_setting_value` int(11) NOT NULL,
)

type User struct {
    Id         int    `db:"pk" column:"user_id"`
    Username string
}
type UserSetting struct {
    UserId int `db:"pk,not_ai"`
    SomeSettingValue int `db:"pk"`
}

user := &User {
    Username : "USER_NAME",
}
db.Insert(user)
setting := &UserSetting {
    UserId : user.Id,
    SomeSettingValue: 1
}
db.Insert(setting)