本來應該係過幾日先寫，但係更新緊個table發現咗呢個問題，立即過黎寫低先...
喺Laravel裡面，migrations係用黎做類似database版嘅version control，你可以用諸如php artisan migrate或者php artisan migrate:rollback去更新或者還原database入面嘅table structure。由於呢幾日喺度搞緊User Management嗰邊嘅table，所以就喺rollback嗰陣遇上咗問題。
問題code:
/**
* Run the migrations.
*
* @return void
*/
public function up()
{
Schema::table('dummy' function(Blueprint $table) {
$table->increments('id')->first();
});
}
/**
* Reverse the migrations.
*
* @return void
*/
public function down()
{
Schema::table('dummy', function(Blueprint $table) {
$table->dropPrimary(['id']);
$table->dropColumn('id');
});
}
* Run the migrations.
*
* @return void
*/
public function up()
{
Schema::table('dummy' function(Blueprint $table) {
$table->increments('id')->first();
});
}
/**
* Reverse the migrations.
*
* @return void
*/
public function down()
{
Schema::table('dummy', function(Blueprint $table) {
$table->dropPrimary(['id']);
$table->dropColumn('id');
});
}
喺更新嘅位我加咗一個會Auto-increment嘅id欄位並作為primary key存在，而當我要還原嘅時候應該係要首先將id嘅primary key屬性移除先再去將成個欄位刪走。不過好不幸地，當我rollback嗰陣出現咗以下嘅錯誤:
SQLSTATE[42000]: Syntax error or access violation: 1075 Incorrect table definition; there can be only one auto column and it must be defined as a key
於是就諗起我要首先將個auto-increment特性移除咗先，但係Laravel嘅說明文檔無一個modifier係有呢個功能。結果喺上網搵完resource後發現原來我可以咁樣...
public function down()
{
Schema::table('dummy', function(Blueprint $table) {
$table->integer('id')->unsigned()->change();
$table->dropPrimary(['id']);
$table->dropColumn('id');
});
}
{
Schema::table('dummy', function(Blueprint $table) {
$table->integer('id')->unsigned()->change();
$table->dropPrimary(['id']);
$table->dropColumn('id');
});
}
利用change()嘅method將id欄位嘅unsign特性移走，咁就會順手無咗auto-increment嘅效果。之後就可以成功rollback啦。