Question

我有这个功能，但它不能100％工作，我不确定为什么。目前我加载了发票模板，它显示为0001。

如果我添加发票，它会被添加到数据库中，它的意思是如果最新的行不等于0001，那么将其设为0002，依此类推，如果它是1872则会进行下一次编号来自MySQL的最新发票。

PHP

define('INVOICE_INITIAL_VALUE','0001');    

// Connect to the database
        $mysqli = new mysqli(DATABASE_HOST, DATABASE_USER, DATABASE_PASS, DATABASE_NAME);

        // output any connection error
        if ($mysqli->connect_error) {
            die('Error : ('. $mysqli->connect_errno .') '. $mysqli->connect_error);
        }

        $query = "SELECT invoice FROM invoices ORDER BY invoice DESC LIMIT 1";

        // mysqli select query
        $result = $mysqli->query($query);

        // get number of returned results, if 0 action it below
        $row_cnt = $result->num_rows;

        //Invoice length
        $invoice = $row['invoice'];

        if($row_cnt == "0"){
            echo INVOICE_INITIAL_VALUE;
        } else {
            // check if the initial invoice ID has already been used and if not start from that value else from the next value
            if($invoice != INVOICE_INITIAL_VALUE) {
                echo ++$invoice;
            }
        }

        // Frees the memory associated with a result
        $result->free();

        // close connection 
        $mysqli->close();

更新如下：

if ($result = $mysqli->query($query)) {

        $row_cnt = $result->num_rows;

        /* fetch object array */
        while ($row = $result->fetch_row()) {
            $invoice = $row['invoice'];
        }

        if($row_cnt == "0"){
            echo INVOICE_INITIAL_VALUE;
        } else {
            // check if the initial invoice ID has already been used and if not start from that value else from the next value
            if($invoice != INVOICE_INITIAL_VALUE) {
                echo ++$invoice;
            }
        }

        // Frees the memory associated with a result
        $result->free();

        // close connection 
        $mysqli->close();
    }

Answer 1

这样做的权利是将字符串转换为整数。然后用前导0转换回来。如下例所示：

$num = '0001'; // string('0001')
$invoiceNumber = intval($num) + 1; // integer(2)
$invoice = str_pad($invoiceNumber, 4, '0', STR_PAD_LEFT); // string('0002')

因此您应该在代码中将其更改为：

else if($invoice != INVOICE_INITIAL_VALUE) {
    $num = intval($invoice) + 1;
    $invoice = str_pad($num, 4, '0', STR_PAD_LEFT);
    echo $invoice;
}

虽然您应该将数据保存为整数，并将其显示为前导零。

Answer 2

除了Dan Revah建议之外，你应该纠正你的if语句的逻辑。

if($invoice != INVOICE_INITIAL_VALUE) {

在上面一行中，您正在检查$ invoice是否不等于1，只有这样才能为其添加1。

因此，当$ invoice等于1时，您不会添加1.这就是您获得001的原因之一。

使用PHP增加MySQL数据库的价值

2 个答案: