使用eloquent创建表

Question

我正在尝试使用eloquent在Laravel中创建一个表。它将每个整数属性视为auto_increment primary key。

另外，在创建表定义时，我是否可以声明字段是否为空。就像属性道布为空一样，我怎么能在这里把这个字段DOB声明为NULL呢？

模型代码块

public function up()
    {
        Schema::create('devotees', function (Blueprint $table) {
            $table->increments('id');
            $table->integer('Category', 1);
            $table->string('NAME',150);
            $table->integer('GENDER',1);
            $table->string('BGROUP',4);
            $table->string('DOB',10);
            $table->timestamps();
        });
    }

获取错误的原因：

 Illuminate\Database\QueryException  : 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 (SQL: create table `devotees` (`id` int unsigned not null auto_increment primary key, `Category` int not null auto_increment primary key, `NAME` varchar(150) not null, `GENDER` int not null auto_increment primary key, `BGROUP` varchar(4) not null, `DOB` varchar(10) not null, `created_at` timestamp null, `updated_at` timestamp null) default character set utf8mb4 collate 'utf8mb4_unicode_ci')

  at C:\xampp\htdocs\laravel\lsapp\vendor\laravel\framework\src\Illuminate\Database\Connection.php:664
    660|         // If an exception occurs when attempting to run a query, we'll format the error
    661|         // message to include the bindings with SQL, which will make this exception a
    662|         // lot more helpful to the developer instead of just the database's errors.
    663|         catch (Exception $e) {
  > 664|             throw new QueryException(
    665|                 $query, $this->prepareBindings($bindings), $e
    666|             );
    667|         }
    668|

  Exception trace:

  1   PDOException::("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")
      C:\xampp\htdocs\laravel\lsapp\vendor\laravel\framework\src\Illuminate\Database\Connection.php:458

  2   PDOStatement::execute()
      C:\xampp\htdocs\laravel\lsapp\vendor\laravel\framework\src\Illuminate\Database\Connection.php:458

如何解决这两个问题？

Answer 1

integer的第二个参数确定该列是否为自动增量字段。有关更多详细信息，请参阅here。因此，对于您的情况，像这样删除第二个参数，您可以通过链接可空方法使字段为空：

$table->integer('Category')

或者，如果您计划使用微整型，则可以使用以下命令：

$table->tinyInteger('Category')

如何使字段可为空

$table->string('DOB', 10)->nullable();

Answer 2

   /**
     * Create a new integer (4-byte) column on the table.
     *
     * @param  string  $column
     * @param  bool  $autoIncrement
     * @param  bool  $unsigned
     * @return \Illuminate\Support\Fluent
     */
    public function integer($column, $autoIncrement = false, $unsigned = false)
    {
        return $this->addColumn('integer', $column, compact('autoIncrement', 'unsigned'));
    }

这是Blueprint.php的integer()函数。正如您所看到的，它在这里需要一个布尔参数。看起来您正在尝试为大小添加一个参数。您不能在Laravel中指定整数的大小。

  Schema::create('devotees', function (Blueprint $table) {
            $table->increments('id');
            $table->integer('Category');
            $table->string('NAME',150);
            $table->integer('GENDER');
            $table->string('BGROUP',4);
            $table->string('DOB',10);
            $table->timestamps();
        });

这可以很好地工作。

Answer 3

尝试使用tinyInteger或仅移除整型字段的大小参数

$table->tinyInteger('Category');
// or
$table->integer('Category');