Schema::create('students', function (Blueprint $table) {
$table->id();
$table->integer('age')->unsigned();
$table->integer('city_id')->unsigned();
$table->foreign('city_id')->references('id')->on('cities')->onDelete('cascade');
$table->timestamps();
});
Schema::create('cities', function (Blueprint $table) {
$table->id();
$table->text('name');
$table->timestamps();
});
我是新的 laravel，當我在終端秀中運行遷移時
SQLSTATE [HY000]：一般錯誤：1215 無法添加外鍵約束（SQL：洗掉級聯時更改表students添加約束students_city_id_foreign外鍵（city_id）參考cities（ ））id
幫我修
uj5u.com熱心網友回復：
您的問題出在代碼順序上。您想為尚不存在的表創建外鍵。
試試這個：
Schema::create('students', function (Blueprint $table) {
$table->id();
$table->integer('age')->unsigned();
$table->integer('city_id')->unsigned();
$table->timestamps();
});
Schema::create('cities', function (Blueprint $table) {
$table->id();
$table->text('name');
$table->timestamps();
});
Schema::table('students', function(Blueprint $table) {
$table->foreign('city_id')->references('id')->on('cities')->onDelete('cascade');
});
像這樣，您首先創建兩個表，然后設定外鍵。
uj5u.com熱心網友回復：
如果你正在使用更新版本的 Laravelid欄位，現在是unsignedBigInteger欄位。因此，您應該執行以下操作：
Schema::create('cities', function (Blueprint $table) {
$table->id();
$table->text('name');
$table->timestamps();
});
Schema::create('students', function (Blueprint $table) {
$table->id();
$table->integer('age')->unsigned();
$table->foreignId('city_id')->constrained()->onDelete('cascade');
$table->timestamps();
});
此外，請確保城市遷移在學生之前進行。
uj5u.com熱心網友回復：
=>your cities migration first create then after students migration create because your city_id foreign key reference to the cities table laravel migration check order and order wise migration run so first cities migration run(cities table create) then students migration run.
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