db_add_field db_change_field, drupal 6, drupal 7下的异同

6	`db_change_field(&$ret, $table, $field, $field_new, $spec, $keys_new = array())`
7	`db_change_field($table, $field, $field_new, $spec, $keys_new = array())`

6	`db_add_field(&$ret, $table, $field, $spec, $keys_new = array())`
7	`db_add_field($table, $field, $spec, $keys_new = array())`

我们在升级站点是,flag模块，升级时报错，

flag_actions module

Update #6200

Failed: DatabaseSchemaObjectDoesNotExistException: Cannot add field <em class="placeholder"></em>.<em class="placeholder">flag_actions</em>: table doesn't exist. in DatabaseSchema_mysql->addField() (line 321 of F:\xampp\htdocs\zuowen\includes\database\mysql\schema.inc).

我仔细的检查了这个模块的

•6200 - Add a "repeat_threshold" value to all existing Flag actions.

通过对比数据库，发现这段代码：

db_add_field($ret, 'flag_actions', 'repeat_threshold', $column);

没有起作用，查了一下API，发现Drupal6，drupal7的API变了，我的代码里还是6的，把它改为Drupal7的，重新运行update.php。正常了。