PHP脚本本地XAMPP运行正常，服务器仅显示空白页求助

Hey Rahul, blank pages on production are almost always due to suppressed errors—let's break this down step by step to fix it:

1. First, Uncover Hidden Errors #

Production servers usually disable error display for security, but we can temporarily enable it to see exactly what's breaking. Add this at the very top of your script:

ini_set('display_errors', 1);
ini_set('display_startup_errors', 1);
error_reporting(E_ALL);

This will replace the blank screen with a specific error message (like a SQL syntax issue or undefined variable) that points us to the problem.

2. Fix Critical SQL Logic Bug #

Looking at your first query, there's an operator priority mistake that's almost certainly causing unexpected results (or no results) on production:
Your current WHERE clause:

WHERE sale_status='paid' OR sale_status='in process' AND YEAR(date) = YEAR(CURDATE())

Since AND has higher priority than OR, this gets interpreted as:
sale_status='paid' OR (sale_status='in process' AND YEAR(date) = CURRENT YEAR)
This is almost definitely not what you intended. Wrap the OR conditions in parentheses to group them correctly:

WHERE (sale_status='paid' OR sale_status='in process') AND YEAR(date) = YEAR(CURDATE())

This ensures both statuses are filtered to only entries from the current year.

3. Fix the Truncated SQL Query #

Your second query is cut off mid-statement:

$bar2=$conn->query("SELECT DATE_FORMAT(date,'%m')as mn,sum(amou...");

If this is how your actual code exists, it's a syntax error (unclosed string, incomplete sum() function). Finish the query—for example, if the column name is amount, update it to:

$bar2=$conn->query("SELECT DATE_FORMAT(date,'%m')as mn,sum(amount)as am FROM ENTRY WHERE [your conditions here] GROUP BY mn");

4. Add Error Checks for Database Operations #

You're assuming the database connection and queries always succeed—add safeguards to catch failures:

• Verify the connection works:

require_once("config.php");
if (!$conn) {
    die("Connection failed: " . mysqli_connect_error());
}

• Check if queries execute successfully:

$bar = $conn->query("YOUR CORRECTED FIRST QUERY HERE");
if (!$bar) {
    die("First query failed: " . $conn->error);
}

Repeat this check for $bar2 to catch any SQL syntax or production database permission issues.

5. Minor PHP Version Edge Case #

While PHP 7.1 vs 7.2 shouldn't break your core logic, initialize the $arry array before using it to avoid implicit initialization quirks:

$arry = []; // Add this right before your while loop
while($arr=$bar->fetch_assoc()){
    $arry[array_shift($arr)]=$arr['am'];
}

Once you implement these steps, you'll either see the specific error to fix or your script will start working as expected.

内容的提问来源于stack exchange，提问作者Rahul