运行迁移时如何修复外键错误

How to fix foreign key error when running migration(运行迁移时如何修复外键错误)

问题描述

我不知道为什么它仍然不起作用并显示这个:

I don't know why it's still don't work and show this:

IlluminateDatabaseQueryException : SQLSTATE[HY000]: 一般错误:1005 无法创建表 db_rocnikovka.books(错误号:150外键约束的格式不正确")(SQL:alter tablebooks 添加约束 books_doba_foreign 外键(doba)参考 druh_knihies (id_druhu))

IlluminateDatabaseQueryException : SQLSTATE[HY000]: General error: 1005 Can't create table db_rocnikovka.books (errno: 150 "Foreign key constraint is incorrectly formed") (SQL: alter table books add constraint books_doba_foreign foreign key (doba) references druh_knihies (id_druhu))

在 C:xampphtdocsRocnikovkavendorlaravelframeworksrcIlluminateDatabaseConnection.php:665

at C:xampphtdocsRocnikovkavendorlaravelframeworksrcIlluminateDatabaseConnection.php:665

异常跟踪:1 PDOException::("SQLSTATE[HY000]: 一般错误: 1005 无法创建 > 表 db_rocnikovka.books (errno: 150 "外键约束格式不正确")")C:xampphtdocsRocnikovkavendorlaravelframeworksrcIlluminateDatabaseConnection.php:459

Exception trace: 1 PDOException::("SQLSTATE[HY000]: General error: 1005 Can't create > table db_rocnikovka.books (errno: 150 "Foreign key constraint is incorrectly formed")") C:xampphtdocsRocnikovkavendorlaravelframeworksrcIlluminateDatabaseConnection.php:459

2 PDOStatement::execute()

2 PDOStatement::execute()

  C:xampphtdocsRocnikovkavendorlaravelframeworksrcIlluminateDatabaseConnection.php:459

 catch (Exception $e) {
    throw new QueryException(
       $query, $this->prepareBindings($bindings), $e
    );
 }

第一张桌子

class CreateDruhKnihiesTable extends Migration
{
    public function up()
    {
        Schema::create('druh_knihies', function (Blueprint $table) {
            $table->bigIncrements('id_druhu');
            $table->string('nazev');
            $table->timestamps();
        });
    }

    public function down()
    {
        Schema::dropIfExists('druh_knihies');
    }
}

第二张表

class CreateBooksTable extends Migration
{
    public function up()
    {
        Schema::create('books', function (Blueprint $table) {
            $table->bigIncrements('id_book');
            $table->string('nazev');
            $table->string('autor');
            $table->string('druh');
            $table->unsignedInteger('doba');
            $table->foreign('doba')->references('id_druhu')->on('druh_knihies');
            $table->integer('pocet_stranek');
            $table->timestamps();
        });
    }

    public function down()
    {
        Schema::dropIfExists('books');
    }
}

推荐答案

你的外键需要和它引用的键具有相同的类型.因此第二个表外键doba需要改成这个，因为你在第一个表主键中使用了BigIncrements().

You foreign key needs to have the same type as the key it references. Therefor the second table foreign key doba needs to be change to this, becuase you use BigIncrements() in the first table primary key.

$table->unsignedBigInteger('doba');

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