我使用这样的迁移创建了一个表:
public function up()
{
Schema::create('despatch_discrepancies', function($table) {
$table->increments('id')->unsigned();
$table->integer('pick_id')->unsigned();
$table->foreign('pick_id')->references('id')->on('picks');
$table->integer('pick_detail_id')->unsigned();
$table->foreign('pick_detail_id')->references('id')->on('pick_details');
$table->integer('original_qty')->unsigned();
$table->integer('shipped_qty')->unsigned();
});
}
public function down()
{
Schema::drop('despatch_discrepancies');
}
我需要更改此表并删除外键引用&列pick_detail_id
并在sku
列之后添加名为pick_id
的新varchar列。
所以,我创建了另一个迁移,如下所示:
public function up()
{
Schema::table('despatch_discrepancies', function($table)
{
$table->dropForeign('pick_detail_id');
$table->dropColumn('pick_detail_id');
$table->string('sku', 20)->after('pick_id');
});
}
public function down()
{
Schema::table('despatch_discrepancies', function($table)
{
$table->integer('pick_detail_id')->unsigned();
$table->foreign('pick_detail_id')->references('id')->on('pick_details');
$table->dropColumn('sku');
});
}
当我运行此迁移时,出现以下错误:
[照亮\数据库\ QueryException]
SQLSTATE [HY000]:常规错误:1025重命名时出错 './dev_iwms_reboot/despatch_discrepancies'到 './dev_iwms_reboot/#sql2-67c-17c464'(错误号:152)(SQL:alter tabledespatch_discrepancies
删除外键pick_detail_id)[PDOException]
SQLSTATE [HY000]:常规错误:1025重命名时出错 './dev_iwms_reboot/despatch_discrepancies'到 './dev_iwms_reboot/#sql2-67c-17c464'(错误号码:152)
当我尝试通过运行php artisan migrate:rollback
命令来反转此迁移时,我收到一条Rolled back
消息,但它实际上并没有在数据库中执行任何操作。
知道可能出错的是什么?如何删除具有外键引用的列?
答案 0 :(得分:113)
您可以使用:
$table->dropForeign(['pick_detail_id']);
$table->dropColumn('pick_detail_id');
如果你在dropForeign源代码中取得一个峰值,那么如果你将列名称作为数组传递,它将为你构建外键索引名称。
答案 1 :(得分:63)
$table->integer('pick_detail_id')->unsigned();
$table->foreign('pick_detail_id')->references('id')->on('pick_details');
Laravel唯一地命名外键引用,如下所示:
<table_name>_<foreign_table_name>_<column_name>_foreign
despatch_discrepancies_pick_detail_id_foreign (in my case)
因此,当您想要删除具有外键引用的列时,您必须这样做:
$table->dropForeign('despatch_discrepancies_pick_detail_id_foreign');
$table->dropColumn('pick_detail_id');
Laravel 4.2+引入了一种新的命名约定:
<table_name>_<column_name>_foreign
答案 2 :(得分:13)
我的表中有多个外键,然后我必须通过在down方法中将列名作为数组索引来逐个删除外键约束:
public function up()
{
Schema::table('offices', function (Blueprint $table) {
$table->unsignedInteger('country_id')->nullable();
$table->foreign('country_id')
->references('id')
->on('countries')
->onDelete('cascade');
$table->unsignedInteger('stateprovince_id')->nullable();
$table->foreign('stateprovince_id')
->references('id')
->on('stateprovince')
->onDelete('cascade');
$table->unsignedInteger('city_id')->nullable();
$table->foreign('city_id')
->references('id')
->on('cities')
->onDelete('cascade');
});
}
/**
* Reverse the migrations.
*
* @return void
*/
public function down()
{
Schema::table('offices', function (Blueprint $table) {
$table->dropForeign(['country_id']);
$table->dropForeign(['stateprovince_id']);
$table->dropForeign(['city_id']);
$table->dropColumn(['country_id','stateprovince_id','city_id']);
});
}
使用以下语句不起作用
$table->dropForeign(['country_id','stateprovince_id','city_id']);
因为dropForeign不会将它们视为我们要删除的单独列。所以我们必须逐一删除它们。
答案 3 :(得分:10)
传递一个名为
的数组$table->dropForeign(['user_id']);
答案 4 :(得分:9)
解决此问题的关键是确保$ table-&gt; dropForeign()命令传递正确的关系名称,而不一定是列名。你做不想要传递列名,因为更直观的恕我直言。
对我有用的是:
$table->dropForeign('local_table_foreign_id_foreign');
$table->column('foreign_id');
因此我传递给dropForeign()的字符串的格式为:
[本地表格] _ [外键字段] _foreign
如果您可以访问Sequel Pro或Navicat等工具,那么能够对这些工具进行可视化非常有帮助。
答案 5 :(得分:4)
我遇到的事情是我不知道在哪里放Schema::table
块。
后来我发现关键是SQL错误:
[Illuminate\Database\QueryException]
SQLSTATE[23000]: Integrity constraint violation: 1217 Cannot delete or update a parent row: a foreign key constraint fails (SQL: drop table if exists `lu_benefits_categories`)
因此,Schema::table
块需要进入down()
迁移的lu_benefits_categories
函数以及Schema::dropIfExists
行之前:
public function down()
{
Schema::table('table', function (Blueprint $table) {
$table->dropForeign('table_category_id_foreign');
$table->dropColumn('category_id');
});
Schema::dropIfExists('lu_benefits_categories');
}
之后,php artisan migrate:refresh
或php artisan migrate:reset
就可以了。
答案 6 :(得分:0)
您可以先禁用关系 ID
Schema::disableForeignKeyConstraints();