Query-builder-in-laravel

notes for some essential query builder methods.

we will use users and posts table for applying q-builder methods

user table :

Schema::create('users', function (Blueprint $table) {
            $table->id();
            $table->string('name');
            $table->string('email')->unique();
            $table->timestamp('email_verified_at')->nullable();
            $table->string('password');
            $table->rememberToken();
            $table->timestamps();
 });

post table:

Schema::create('posts', function (Blueprint $table) {
            $table->id();
            $table->string('title');
            $table->foreignId('user_id')->constrained('users')->cascadeOnDelete();
            $table->string('slug')->nullable();
            $table->text('excerpt')->nullable();
            $table->longText('description')->nullable();
            $table->boolean('is_published')->default(false);
            $table->integer('min_to_read')->nullable();
            $table->timestamps();
});

Now we will link up user and post model for one to many relationship with these methods in Models/User.php file and Models/Post.php file

User Model :

public function post():HasMany{ 
//here one user has many post 
        return $this->hasMany(Post::class) ; 
}
//accessing post data from user 
$user_table_instance->post()->post_table_column_data

Post Model :

public function user(){
//      one post belongs to one user 
        return $this->belongsTo(User::class) ; 
}
//accessing user data from post 
$post_table_instance->user()->user_table_column_data

Now its time to seed or insert some data manually in users and posts table.

After these , we are ready to use methods of query builder

Codes from in PostController.php

//here we grab table named "posts" and tell return me 
//all data of posts table 
$posts = DB::table('posts')->get() ; 

//After targeting 'posts' table we select
//a column named 'title' in 'posts' table 
// and get all data of 'posts' table these query 
//will return us posts table all data with 'title' columns only 
 $posts = DB::table('posts')->select('title')->get() ; 

//another example for select method these query will return 
//us all 'posts' table data
// with column name 'title' and 'excerpt'
$posts = DB::table('posts')->select('title','excerpt')->get() ;

//these query will return same data as previous query
// the difference between this and previous query is 
// we must read 'excerpt' values with modified name 'ex'
$posts = DB::table('posts')->select('title','excerpt as ex')->get() ; 

//these will return the unique or distinct values 
//of 'is_published' column of 'posts' table
//please dd to observe output
$posts = DB::table('posts')->select('is_published')->distinct()->get() ; 

//return all data of 'posts' table with 'title' and 'is_published'
//values 
$example = DB::table('posts')->select('title','is_published')->get(); 

//this query will return same results
 $posts = DB::table('posts')->select('is_published'); 
 $example = $posts->addSelect('title')->get() ; 
 dd($example) ;

//this query will return a array of 'posts' table row/element
//where value of id column is equal to 2
//->get() method return data as array
//where is a method that check the condition and pass
// responsibility to next chained method , here get()
// where('column_name','to be searched value') it works like
// if('column_name' == 'to be searched value')
   // return matched data
//else
    //return null value
$posts = DB::table('posts')->where('id',2)->get();

//another method example named ->first()
//first method will return checked and matched data 
//as a object
$posts = DB::table('posts')->where('id',2)->first();

//in this query where() method will check condition is ok 
//or not if not then $posts will be null, if condition inside
//where method is true then it will return row values
//with id=2 now chained method value() almost similar to select
//method,value('title') will return title column value only.
//difference between select() and value() is select can return 
//more then one column data and value() can return single column
//data only
$posts = DB::table('posts')->where('id',2)->value('title');


//this query will return a row data matched with id 2 
//return type will be object
$posts = DB::table('posts')->find(id:2);

previous queries was something like , at first we select a row data of

'posts' table then we retrieving column data from our targeted row.

'posts_table'->'targeted_row'->'column_value_of_targeted_row'

here is a query method named pluck() ,we can use this method all column

data of "posts" table.

'posts_table'->'targeted_column_values'

//obiviously it will return all column data of 
//'posts' table and return type will be 'array'
$posts = DB::table('posts')->pluck('title');

inserting data using query builder insertOrIgnore() method $posts =

 $posts = DB::table('posts')->insertOrIgnore([
            'id' => 1000,
            'title' => 'post-title-5',
            'user_id' => 2,
            'slug' => 'post-slug-5',
            'excerpt' => 'excerpt-5' , 
            'description' => 'description-5',
            'is_published' => 0,
            'min_to_read' => 8
        ]);
dd($posts);
//this query will insert data to 'posts' table
//want to insert more then one row of data in one load then here is 
//the example for insert more then one row of data 
$posts = DB::table('posts')->insertOrIgnore(
            [
                'id' => 2000,
                'title' => 'post-title-6',
                'user_id' => 2,
                'slug' => 'post-slug-6',
                'excerpt' => 'excerpt-6' , 
                'description' => 'description-6',
                'is_published' => 1,
                'min_to_read' => 8
            ],
            [
                'id' => 3000,
                'title' => 'post-title-7',
                'user_id' => 3,
                'slug' => 'post-slug-7',
                'excerpt' => 'excerpt-7' , 
                'description' => 'description-7',
                'is_published' => 1,
                'min_to_read' => 8
            ]
        );

dd($posts);

now here is upsert() method to insert data in 'posts' table , or update data in 'posts' table

upsert() method accepts two arguments one is 'updated_data' another is 'array of column name' array element may be one or more...

it works like , at first upsert() method search in 'posts' table respect to accepted second argument [array of column name] , if upsert method find or

can matched a record with [array of column name] then upsert method update the targeted data with accepted first argument data.

if upsert method can not find or matched record in 'posts' table then

it will create a new record in 'posts' table with accepted first argument data

finally upsert method first argument data is real data should be inserted or updated , second argument data is for condition checking

$posts = DB::table('posts')->upsert([
                'id' => 2000,
                'title' => 'post-title-6-updated',
                'user_id' => 2,
                'slug' => 'post-slug-6-updated',
                'excerpt' => 'excerpt-6-updated' , 
                'description' => 'description-6-uu',
                'is_published' => 1,
                'min_to_read' => 88
            ],['title','slug']);

        dd($posts) ;

insertGetId() method will create a record and will return the created id number of new record in 'posts' table

  $posts = DB::table('posts')->insertGetId([
                'id' => 8000,
                'title' => 'post-title-88',
                'user_id' => 2,
                'slug' => 'post-slug-99',
                'excerpt' => 'excerpt-99' , 
                'description' => 'description-99',
                'is_published' => 1,
                'min_to_read' => 22
            ],['title','slug']);

        dd($posts) ;

analyse these example code yourself for better understanding

you should be capable enough to understand these codes below

$posts = DB::table('posts')
            ->where('id', '=', 1000)
            ->update([
                'title' => 'updated-title-uu-equal-contion'
            ]);

        $posts = DB::table('posts')
            ->where('id', '<=', 2)
            ->update([
                'title' => 'updated-title-uu-less-then-condition'
            ]);

        $posts = DB::table('posts')
            ->where('id', '>=', 3)
            ->update([
                'title' => 'updated-title-uu-grater-then-condition'
            ]);

        dd($posts);

now it time to delete record from 'posts' table

  $posts = DB::table('posts')->where('id',3000)->delete() ; 
  dd($posts) ;

aggregates methods highly useful method in q-builder

//this count() method will return the number of records in 
//table 
$posts = DB::table('posts')->count() ; 

//this will return the number of is_published true record
$posts = DB::table('posts')->where('is_published',1)->count() ; 

//will return sum of 'min_to_read' columns in 'posts' table 
$posts = DB::table('posts')->sum('min_to_read') ; 

$posts = DB::table('posts')->avg('min_to_read') ; 

//filtering is_published true only
$posts = DB::table('posts')->where('is_published',true)->avg('min_to_read') ; 

$posts = DB::table('posts')->max('min_to_read') ; 

//min method will ignore null values 
$posts = DB::table('posts')->min('min_to_read') ; 

dd($posts) ;

//this query will return all records without matched recode
//inside whereNot() conditional record 
$posts = DB::table('posts')->whereNot('id',2)->get() ; 

//this is will return records with id grater then
//or equal to 2 
$posts = DB::table('posts')
         ->whereNot('id', '<=' ,2)
         ->get() ; 

//this will return "is_published" : false records
$posts = DB::table('posts')
         ->orWhereNot('is_published',true)
         ->get() ; 

//this will return a boolean value , true or false
//based on condition
$posts = DB::table('posts')->where('id',22)->exists() ;

//this will return records contain id between condition
// inclusive result 
$posts = DB::table('posts')->whereBetween('id',[3,2000])->get() ; 

//this returend result will be inverse of whereBetween
$posts = DB::table('posts')->whereNotBetween('id',[3,2000])->get() ;

that's all for basic uses of query builder methods.

this post may be update later with more essential methods and

examples , thank you.