A pair of one or one pairs of one-to-many, Many-to-many, many-to-many practices about table relationships in Laravel

first about the relationship between tables and tables

1. A One-to-many
2. A One-to-many
3. Multiple to One
4. Multi-pair multi- parent table and child table

1. "One" is the parent table
2. One side of "many" is how a child table handles a one-to-many relationship

Building a field in a child table (foreign key) points to the parent table How to handle a many-to-many relationship

Establishing a middle table, transforming "many-to-many" relationship into "one-to-many" Case Analysis

Table One: User table (It_user)
Table II: User Details table (it_user_info)
Table III: Article table (it_article)
Table IV: Country tables (It_country)
Table five: User Role table (it_role)
① One-on-one
The User table (table i) and the Details table (Table II) are one-to-one relationships
② a pair of many
The User table (table i) and the article table (table III) are a one-to-many relationship
③ for one More
User table (Table i) and Country table (table IV) is the relationship between the multiple
④ more than the most
User table (Table i) and role table (table V) is a many-to-many relationship user table building and test data

DROP TABLE IF EXISTS ' it_user ';
CREATE TABLE ' it_user ' (
  ' id ' int ' unsigned not NULL auto_increment COMMENT ' primary key ',
  ' name ' varchar () DEFAULT NU LL COMMENT ' username ',
  ' password ' char (#) default null COMMENT ' password (does not use MD5) ',
  ' country_id ' int (one) default NULL,
  PRIMARY key (' id '),
  key ' Country id ' (' country_id ')
) Engine=myisam auto_increment=6 DEFAULT Charset=utf8;

------------------------------
-Records of It_user
------------------------------
INSERT into ' it_ User ' VALUES (' 1 ', ' xiaoming ', ' 123456 ', ' 1 ');
INSERT into ' it_user ' VALUES (' 2 ', ' Xiaomei ', ' 123456 ', ' 1 ');
INSERT into ' it_user ' VALUES (' 3 ', ' xiaoli-new ', ' 123 ', ' 1 ');

User Detail table and test data

------------------------------
--Table structure for it_user_info
------------------------------
DROP TABLE IF EXISTS ' it_user_info ';
CREATE TABLE ' it_user_info ' (
  ' user_id ' int (one) not null auto_increment,
  ' Tel ' char (one) DEFAULT null,
  ' email ' varchar (128) default NULL,
  ' addr ' varchar (255) default NULL,
  PRIMARY KEY (' user_id ')
) Engine=myisam auto_ increment=4 DEFAULT Charset=utf8;

------------------------------
--Records of It_user_info
------------------------------
INSERT Into ' It_user_info ' VALUES (' 1 ', ' 13012345678 ', ' xiaoming@163.com ', ' Beijing ');
INSERT into ' it_user_info ' VALUES (' 2 ', ' 15923456789 ', ' xiaomei@163.com ', ' Shanghai ');
INSERT into ' it_user_info ' VALUES (' 3 ', ' 18973245670 ', ' xiaoli@163.com ', ' Wuhan ');

Table of articles and test data

------------------------------
--Table structure for it_article
------------------------------
DROP TABLE IF EXISTS ' it_article ';
CREATE TABLE ' it_article ' (
  ' id ' int () NOT NULL auto_increment,
  ' title ' varchar (255) DEFAULT null,
  ' Content ' text,
  ' user_id ' int (one) DEFAULT NULL,
  PRIMARY key (' id '),
  key ' user_id ' (' user_id ')
engine= MyISAM auto_increment=4 DEFAULT Charset=utf8;

------------------------------
--Records of It_article
------------------------------
INSERT into ' It_article ' VALUES (' 1 ', ' The world is so big, I want to see ', ' wallet so small, always not enough ', ' 1 ');
INSERT into ' it_article ' VALUES (' 2 ', ' I want to bump into love ', ' It's touching the Ghost ', ' 2 ');
INSERT into ' it_article ' VALUES (' 3 ', ' hahaha ', ' Hee Hee ', ' 1 ');

National table and test data

------------------------------
--Table structure for it_country
------------------------------
DROP TABLE IF EXISTS ' it_country ';
CREATE TABLE ' it_country ' (
  ' id ' int () NOT NULL auto_increment,
  ' name ' varchar (255) DEFAULT null,
  PRIMARY K EY (' id ')
) Engine=myisam auto_increment=3 DEFAULT Charset=utf8;

------------------------------
--Records of It_country
------------------------------
INSERT into ' It_country ' VALUES (' 1 ', ' China ');
INSERT into ' it_country ' VALUES (' 2 ', ' USA ');

User Role Table building and test data

------------------------------
--table structure for it_role
------------------------------
DROP table IF EXISTS ' it_role ';
CREATE TABLE ' it_role ' (
  ' id ' int () NOT NULL auto_increment,
  ' name ' varchar (255) DEFAULT null,
  PRIMARY KEY ( ' id ')
engine=myisam auto_increment=5 DEFAULT Charset=utf8;

------------------------------
-Records of It_role
------------------------------
INSERT into ' it_ Role ' VALUES (' 1 ', ' development ');
INSERT into ' it_role ' VALUES (' 2 ', ' Test ');
INSERT into ' it_role ' VALUES (' 3 ', ' management ');

User and Role Intermediate table table and test data

------------------------------
--Table structure for it_user_role
------------------------------
DROP TABLE IF EXISTS ' it_user_role ';
CREATE TABLE ' it_user_role ' (
  ' user_id ' int () default null,
  ' role_id ' int (one) default null,
  KEY ' role_id ' ( ' role_id '),
  KEY ' user_id ' (' user_id ')
) Engine=myisam DEFAULT Charset=utf8;

------------------------------
--Records of It_user_role
------------------------------
INSERT Into ' It_user_role ' VALUES (' 1 ', ' 1 ');
INSERT into ' it_user_role ' VALUES (' 1 ', ' 2 ');
INSERT into ' it_user_role ' VALUES (' 1 ', ' 3 ');
INSERT into ' it_user_role ' VALUES (' 2 ', ' 1 ');
INSERT into ' it_user_role ' VALUES (' 3 ', ' 2 ');

preparatory work

1. Planning Routing
The following routes are written under routes/web.php:

ORM Association Relationship
Route::get ('/orm/relation/{mode} ', ' orm\usercontroller@relation ');

2. Writing relation method in app/http/controllers/orm/usercontroller.php

    Public function relation ($mode)
    {
        switch ($mode) {case
            ' 1_1 ':
            {
                //one-to-one

            } break
            ;
            Case ' 1_n ':
            {
                //a pair of multiple

            } break
                ;
            Case ' n_1 ':
            {
                //multiple to one

            } break
                ;
            Case ' N_n ':
            {
                //many to many

            } break
                ;
            default;
        }

    }

3, install debug Debugging Tools
3.1 Install using the composer command

Composer require  Barryvdh/laravel-debugbar

3.2, modify the config/app.php file, load Debugbar to laravel into the project, add the following configuration in the ' providers ' array:

Barryvdh\debugbar\serviceprovider::class,

In addition to installing the Debugbar debugging tools, you can also use Query sniffing: Edit the providers/appserviceprovider.php boot method by adding the following code

\db::listen (function ($query) {
    var_dump ($query->sql);
     Var_dump ($query->bindings);
     Echo ' <br> ';
 });

You can also print out the executed SQL statement. One-on-one 1. Create UserInfo Model Objects

Enter the cmd command line to enter the directory where the Laravel project executes the following command
php artisan Make:model Userinfo
Will generate userinfo.php 2, edit userinfo model files in the app directory

<?php

namespace App;

Use Illuminate\database\eloquent\model;

Class Userinfo extends Model
{
    protected $table  =  ' User_info ';
    protected $primaryKey = ' user_id ';
    protected $fillable = [' user_id ', ' tel ', ' email ', ' addr '];
    Public    $timestamps = false;
}

3, Write Usermodel, add a one-to-one approach

<?php

namespace App;

Use Illuminate\database\eloquent\model;

Class Usermodel extends Model
{
    protected $table = ' user '; the table name
    protected $primaryKey = ' id ';//primary key field, default is id< c6/>protected $fillable = [' name ', ' Password '];//the field that can be manipulated is public
    $timestamps = false;//If there are no created_at and updated_ in the datasheet ID field, $timestamps can not set, default to True public

    function Userinfo () {/
         * * @param [string] [name] [ Model class name that needs to be associated]
         * @param [string] [foreign] [parameter a field in the specified datasheet]
         *
        /return $this->hasone (' App\userinfo ', ' user_id ');
    }

4, write Usercontroller, call one-to-one method

    Public function relation ($mode)
    {
        switch ($mode) {case
            ' 1_1 ':
            {
                //one-to-one
                $data = Usermodel::find (1)->userinfo ()->get ();
                DD ($data);
            break;

            default;
        }

    }  

A pair of many 1. Create Article Model objects

Execute command
php artisan Make:model Article
Generate article.php file 2 under App , write article model file

<?php

namespace App;

Use Illuminate\database\eloquent\model;

Class Article extends Model
{
    protected $table = ' Article ';
    Protected $primaryKey = ' id ';
    protected $fillable = [' id ', ' title ', ' content ', ' user_id '];
    Public $timestamps  = false;
}

3, Write Usermodel, add a pair of multiple methods

Public Function artice ()
    {return
        $this->hasmany (' app\article ', ' user_id ');
    }

4, write Usercontroller, call a one-to-many approach

    Public function relation ($mode)
    {
        switch ($mode) {case
            ' 1_1 ':
            {
                //one-to-one
                $data = Usermodel:: Find (1)->userinfo ()->get ();
                DD ($data);
            break;
            Case ' 1_n ':
            {
                //one-to-many
                $data = usermodel::find (1)->artice ()->get ();
                DD ($data);
                break;

            Default;}}}

more to one 1. Create Country Model objects

Execute command

php artisan Make:model Country 2. Write Country model files

<?php

namespace App;

Use Illuminate\database\eloquent\model;

Class Country extends Model
{
    protected $table = ' Country ';   Real table name
    protected $primaryKey = "id";   Primary Key ID
    protected $fillable = [' id ', ' name '];    The field that is allowed to operate is public
    $timestamps  =false;//If there are no Created_at and updated_id fields in the datasheet, $timestamps can not set, default to True

}

3, Write Usermodel, add a more than one method

Public Function Country ()
{return
    $this->belongsto (' app\country ', ' country_id ');
}

4, write Usercontroller, call the method

Public function relation ($mode)
    {
        switch ($mode) {case
            ' 1_1 ':
            {
                //one-to-one
                $data = Usermodel:: Find (1)->userinfo ()->get ();
                DD ($data);
            break;
            Case ' 1_n ':
            {
                //one-to-many
                $data = usermodel::find (1)->artice ()->get ();
                DD ($data);
                break;
            Case ' n_1 ':
            {
                //multiple pairs of one
                $data = Usermodel::find (1)->country ()->get
                (); DD ($data);
                break;

            Default;}}}

many to many 1. Create Role Model Objects

Execute command
PHP artisan Make:model role
Execute command
php artisan Make:model user_role 2. Writing role model

<?php

namespace App;

Use Illuminate\database\eloquent\model;

Class Role extends Model
{
    protected $table = ' role ';
    Protected $primaryKey = "id";
    protected $fillable = [' name '];
    Public $timestamps  =false;

}

writing the User_role model

Because there are no primary key fields in the table, you need two fields to

<?php

namespace App;

Use Illuminate\database\eloquent\model;

Class User_role extends Model
{
    protected $table = ' user_role ';
    Public $timestamps  =false;

}

3, Write Usermodel, add many to many methods

    Public Function Role () {
        /
         * * * The first parameter: the corresponding class for the table to be associated
         * The second parameter: The table name of the middle table
         * Third parameter: The foreign key for the current table corresponding to the intermediate table
         * Fourth parameter: The table to be associated with the middle table corresponding to the foreign key
         *
        /return $this->belongstomany (' app\role ', ' user_role ', ' user_id ', ' role_id ');
    

4, write Usercontroller, call many to many methods

Public function relation ($mode)
{
    switch ($mode) {case
        ' 1_1 ':
        {
            //one-to-one
            $data = Usermodel:: Find (1)->userinfo ()->get ();
            DD ($data);
        break;
        Case ' 1_n ':
        {
            //one-to-many
            $data = usermodel::find (1)->artice ()->get ();
            DD ($data);
            break;
        Case ' n_1 ':
        {
            //multiple pairs of one
            $data = Usermodel::find (1)->country ()->get
            (); DD ($data);
            break;
        Case ' N_n ':
        {
            //many-to-many
           $data = Usermodel::find (2)->role ()->get
           (); DD ($data);
            break;
        default;
    }

}

Summarize:
1, one-to-one use:hasone ()
2, a One-to-many use method:hasmany ()
3, multiple to one use method:Belongsto ()
4. Multi-use Method:belongstomany ()