laravel 5.6 configuracion base de datos migraciones

en config/database.php

'default' => env('DB_CONNECTION', 'mysql'),

quiere decir que busca en el archivo .env la variable DB_CONNECTION
en nuestro caso es igual a mysql...

si no existiera esa variable toma el valor del 2do parametro 'mysql'

en .env debemos definir esa y otras variables

DB_CONNECTION=mysql
DB_HOST=127.0.0.1
DB_PORT=3306
DB_DATABASE=db_blog
DB_USERNAME=root
DB_PASSWORD=

las migraciones es una suerte de control de versiones de nuestra base de datos,
estas se encuentran en database/migrations

por default Laravel viene con 2 migraciones de users y passwords.


cada migracion tiene 2 funciones up() y down()

veamos la up() de users
 public function up()
    {
        Schema::create('users', function (Blueprint $table) {
            $table->increments('id');
            $table->string('name');
            $table->string('email')->unique();
            $table->string('password');
            $table->rememberToken();
            $table->timestamps();
        });
    }


donde  $table->rememberToken()
es lo mismo que escribir (ver metodo en Blueprint)

$this->string('remember_token', 100)->nullable();

y donde

 $table->timestamps();

es lo mismo que escribir:

$this->timestamp('created_at', $precision)->nullable();
$this->timestamp('updated_at', $precision)->nullable();

para ejecutar todas estas migraciones desde la consola escribimos:

php artisan migrate

para hacer un rollback (o llamar a las funciones down() de todas las migraciones que se ejecutaron en el ultimo migrate) desde la consola escribimos:

php artisan migrate:rollback

para crear una migration usamos

php artisan make:migration create_messages_table

esto nos creara un archivo con la fecha y hora p.e 2018_03_21_122354_create_messages_table.php
con los metodos vacios, si queremos generar automaticamente un archivo de migration para la creacion de una tabla hacemos

php artisan make:migration create_messages_table --create=messages



ahora si, el archivo creado tiene implementado minimamente la funcion up()

 public function up()
    {
        Schema::create('messages', function (Blueprint $table) {
            $table->increments('id');
            $table->timestamps();
        });
    }


y lo completamos con los datos que queremos

 public function up()
    {
        Schema::create('messages', function (Blueprint $table) {
            $table->increments('id');
            $table->string('nombre');
            $table->string('email');
            $table->text('mensaje');
           
            $table->timestamps();
        });
    }

para ejecutar la migration

php artisan migrate

si queremos agregar un campo nuevo

php artisan make:migration add_telefono_messages_table --table=messages

ahora la funcion up del archivo de migration tiene la sgt forma:

  public function up()
    {
        Schema::table('messages', function (Blueprint $table) {
            //
        });
    }

ahora agregamos el campo nuevo y en la funcion down() la sentencia contraria, osea la eliminacion de ese campo:

public function up()
    {
        Schema::table('messages', function (Blueprint $table) {
            $table->string('telefono')->nullable();
        });
    }

    /**
     * Reverse the migrations.
     *
     * @return void
     */
    public function down()
    {
        Schema::table('messages', function (Blueprint $table) {
            $table->dropColumn('telefono');
        });
    }

tip: para recrear totalmente tu base de datos se usa

php artisan migrate:refresh

para hacer migratios que modifican/eliminan columnas de la tabla debemos instalar antes doctrine/dbal asi:

composer require doctrine/dbal






*******************
https://laravel.com/docs/5.6/migrations
campos disponibles para migrations

Command	Description
$table->bigIncrements('id');	Auto-incrementing UNSIGNED BIGINT (primary key) equivalent column.
$table->bigInteger('votes');	BIGINT equivalent column.
$table->binary('data');	BLOB equivalent column.
$table->boolean('confirmed');	BOOLEAN equivalent column.
$table->char('name', 100);	CHAR equivalent column with an optional length.
$table->date('created_at');	DATE equivalent column.
$table->dateTime('created_at');	DATETIME equivalent column.
$table->dateTimeTz('created_at');	DATETIME (with timezone) equivalent column.
$table->decimal('amount', 8, 2);	DECIMAL equivalent column with a precision (total digits) and scale (decimal digits).
$table->double('amount', 8, 2);	DOUBLE equivalent column with a precision (total digits) and scale (decimal digits).
$table->enum('level', ['easy', 'hard']);	ENUM equivalent column.
$table->float('amount', 8, 2);	FLOAT equivalent column with a precision (total digits) and scale (decimal digits).
$table->geometry('positions');	GEOMETRY equivalent column.
$table->geometryCollection('positions');	GEOMETRYCOLLECTION equivalent column.
$table->increments('id');	Auto-incrementing UNSIGNED INTEGER (primary key) equivalent column.
$table->integer('votes');	INTEGER equivalent column.
$table->ipAddress('visitor');	IP address equivalent column.
$table->json('options');	JSON equivalent column.
$table->jsonb('options');	JSONB equivalent column.
$table->lineString('positions');	LINESTRING equivalent column.
$table->longText('description');	LONGTEXT equivalent column.
$table->macAddress('device');	MAC address equivalent column.
$table->mediumIncrements('id');	Auto-incrementing UNSIGNED MEDIUMINT (primary key) equivalent column.
$table->mediumInteger('votes');	MEDIUMINT equivalent column.
$table->mediumText('description');	MEDIUMTEXT equivalent column.
$table->morphs('taggable');	Adds taggable_id UNSIGNED INTEGER and taggable_type VARCHAR equivalent columns.
$table->multiLineString('positions');	MULTILINESTRING equivalent column.
$table->multiPoint('positions');	MULTIPOINT equivalent column.
$table->multiPolygon('positions');	MULTIPOLYGON equivalent column.
$table->nullableMorphs('taggable');	Adds nullable versions of morphs()columns.
$table->nullableTimestamps();	Alias of timestamps() method.
$table->point('position');	POINT equivalent column.
$table->polygon('positions');	POLYGON equivalent column.
$table->rememberToken();	Adds a nullable remember_tokenVARCHAR(100) equivalent column.
$table->smallIncrements('id');	Auto-incrementing UNSIGNED SMALLINT (primary key) equivalent column.
$table->smallInteger('votes');	SMALLINT equivalent column.
$table->softDeletes();	Adds a nullable deleted_at TIMESTAMP equivalent column for soft deletes.
$table->softDeletesTz();	Adds a nullable deleted_at TIMESTAMP (with timezone) equivalent column for soft deletes.
$table->string('name', 100);	VARCHAR equivalent column with a optional length.
$table->text('description');	TEXT equivalent column.
$table->time('sunrise');	TIME equivalent column.
$table->timeTz('sunrise');	TIME (with timezone) equivalent column.
$table->timestamp('added_on');	TIMESTAMP equivalent column.
$table->timestampTz('added_on');	TIMESTAMP (with timezone) equivalent column.
$table->timestamps();	Adds nullable created_at and updated_atTIMESTAMP equivalent columns.
$table->timestampsTz();	Adds nullable created_at and updated_atTIMESTAMP (with timezone) equivalent columns.
$table->tinyIncrements('id');	Auto-incrementing UNSIGNED TINYINT (primary key) equivalent column.
$table->tinyInteger('votes');	TINYINT equivalent column.
$table->unsignedBigInteger('votes');	UNSIGNED BIGINT equivalent column.
$table->unsignedDecimal('amount', 8, 2);	UNSIGNED DECIMAL equivalent column with a precision (total digits) and scale (decimal digits).
$table->unsignedInteger('votes');	UNSIGNED INTEGER equivalent column.
$table->unsignedMediumInteger('votes');	UNSIGNED MEDIUMINT equivalent column.
$table->unsignedSmallInteger('votes');	UNSIGNED SMALLINT equivalent column.
$table->unsignedTinyInteger('votes');	UNSIGNED TINYINT equivalent column.
$table->uuid('id');	UUID equivalent column.
$table->year('birth_year');	YEAR equivalent column.