如何创建一个包含MySQL查询的PHP函数？

Question

Hello at the moment I'm using a PHP file called select_Type.php that contain a MySQL query to create a <select></select> Box into HTML. I'm using include_once to link my admin.php and ./Includes/select_Type.php . I already created a file called ./Includes/functions.php where all my querys should be set in PHP functions .

I would like to learn more about functions.

Admin page admin.php where the <select></select> is :

<?php
session_start();
include_once './Includes/functions.php';

CheckLogIn('Superadmin');
SelectType();
//require_once './Includes/select_Type.php';
require_once './Includes/register.php';
?>

select_type.php :

    <?php
require_once 'functions.php'; 

$querySQL = "SELECT * FROM tbltype";
$queryResult = GetQuery($querySQL);

while ($row = mysqli_fetch_assoc($queryResult)){
    $dataArrayType[] = $row;
}
?>

What I tried:

<?php
function SelectType() {
    GLOBAL $_POST;
    $querySQL = "SELECT * FROM tblType";
    $queryResult=GetQuery($querySQL);

    while ($row = mysqli_fetch_assoc($queryResult)) {
        $dataArrayType[] = $row;
    }
}
?>

What am I doing wrong ?

Thanks in advance :)

Answer 1

You can use this:

function sel($table,$field="*", $condition="1",$sort="" ){
    if($sort!='') $sort="order by $sort ";
    //echo "select $field  from $table where $condition $sort ";
    $sel_query=mysql_query("select $field  from $table where $condition $sort ");
    //$sel_result=array();
    while($temp_res=@mysql_fetch_array($sel_query))
    {
        $sel_result[]=$temp_res;
    }
    return isset($sel_result)?$sel_result: 0;
}

And get result:

$temp_res=sel("post","*"," userid ='".$frnd['friend']."' ORDER BY id DESC");
    if($temp_res)foreach($temp_res as $row){
        echo $row['content'];
    }

Answer 2

Thank you all especially Déjà vu !!!!! You were all very helpfull.

The problem was, how most of you told me: I didn't returned the value.

Before:

<?php
function SelectType() {
    GLOBAL $_POST;
    $querySQL = "SELECT * FROM tblType";
    $queryResult=GetQuery($querySQL);

    while ($row = mysqli_fetch_assoc($queryResult)) {
        $dataArrayType[] = $row;
    }
}
?>

Now:

I deleted the GLOBAL $_POST becauce $_POST is already GLOBAL .(Thanks to ɴ ᴀ ᴛ ʜ)

<?php
function SelectType() {
    $querySQL = "SELECT * FROM tblType";
    $queryResult=GetQuery($querySQL);

    while ($row = mysqli_fetch_assoc($queryResult)) {
        $dataArrayType[] = $row;
    }
    return $dataArrayType;
}
?>

admin.php

I put my function SelectType() in my foreach . Et voila!

    <select type="text" id="register_type" name="register_type" required>
        <?php
        foreach (SelectType() as $row) {
            echo "<option value='" . $row['idType'] . "'>" . $row['dtType'] . '</option>';
        }
        ?>
    </select>