php practical functions, php functions_PHP tutorial

php practical functions, php functions

This is my first essay, let’s write some more practical functions in my work.

Array function:

1 array_column --returns a specified column in the array

Usage 1: Return a specified column in the array

Application scenario: Take out the IDs of all the students in the class and query other information about these students in other tables

Benefits: Reduce the number of database queries (find all information at once through ID)

Liezi:

　

　 $records = array(
　array(
　　last_name' => 'Doe',
),
array(
'id' => 3245,
name' => 'Smith',
)
　);

　$first_names = array_column($records, 'id');
　print_r($first_names);

//Result

array('2135','3245');

　?>

Usage 2: Use the id in the two-dimensional array as the key of the array

Application scenario: retrieve data through array['id']

Benefits: Use array_column instead of foreach to use the id in the two-dimensional array as the key of the array. The code is concise and calling system functions improves efficiency

Liezi:

　 　 $records = array(

　array(

　　last_name' => 'Doe',

),
array(
'id' => 3245,
'first_name' => 'Sally',
'last_ name' => 'Smith',
)
　);

//Use foreach

　$records_key = array();

foreach($records as $k => $v){

　　$records_key[$v['id']] = $v;

　}

　print_r($first_names);

//Call array_column

$records_key = array_column($records, NULL,'id');

print_r($first_names);

　?>

//Result

Array(

> 🎜> > 🎜>

　)

　

2 array_multisort -- Sort multiple arrays or multidimensional arrays

Usage 1: Multi-dimensional array sorting

Application scenario: Sort the data in descending order according to price and in ascending order according to sales volume

Benefits:

Liezi:

　　 $data[] = array('price' => 67, 'sale_num' => 2);

$data[] = array('price' => 86, 'sale_num' => 1);

$data[] = array('price' => 85, 'sale_num' => 6);

$data[] = array('price ' => 98, 'sale_num' => 2);

　 $data[] = array('price' => 86, 'sale_num' => 6);

$data[] = array('price' => 67, 'sale_num' => 7);

// Get the list of columns

　　$price= array_column($data,'price');

　　$sale_num= array_column($data,'sale_num');

　　　 // Take $data as the last parameter and sort by common key

　array_multisort($price, SORT_DESC, $sale_num, SORT_ASC, $data);
　?>

　 //Result　

　　　　 price | sale_num
　　　　-------+--------
  　　　　  98 |       2
 　　　　   86 |       1
　　　　    86 |       6
　　　　    85 |       6
　　　　    67 |       2
  　　　　  67 |       7

To be continued!

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