从另一个php文件调用函数

I have 2 file

file1.php

<?php
      Class A
      {
          public static function _test
          {
          }
      }
      function get_sql($id)
      {
      }
      function get_data($ids)
      {
      }
?>

In file2.php I've written

require_once('file1.php');
  $a = get_sql($id);

Why I cannot call the function and get my result??

try this in file1.php

<?php
  Class A {
     public static function _test {
     }
     function get_sql($id) {
        echo $id;
     }
     function get_data($ids) {
     }
  }
?>

In file2.php first require the file and then code this

require_once('file1.php');
$a = new A();
$a->get_sql($id);

OR send static value in function

$a->get_sql(5);

This is your first mistake in your code

public static function _test{
    }
  } //this bracket is related to the class

it is the question if you want to have functions get_sql() and get_data() as a methods inside the A class:

If yes the code from user2727841 will work after you add the round brackets to the function public static function _test:

public static function _test()
  {
  }

Your code will work too after you add the same brackets to the same function but your function get_sql() and get_data() are outside the class A.

EDIT I thought that these function are outside the class A. Please, add the round brackets to the public static function _test in the class A - it is syntax error - than I hope it will work.

Well for one thing you are not returning anything from the get_sql($id) function.

Assuming you are returning something in your original code; I hope you are aware that the function is not part of the class (its defined outside the scope of the class). But for educational purposes you would call a static method within a class by doing:

$a = A::get_sql($id);

This would also mean the defining the function in the following manner:

  Class A{
          public static function get_sql($id){
            echo $id;
          }
      }