Question

我是PHP和MySql的新手，我已经在互联网上搜索过但无法找到合适的答案。

使用PHP，我需要从MySQL数据库的单个单元格中获取值，并检查该值是否等于0或1.如果它等于1，则将其设置为0，反之亦然

我该怎么办？谢谢你的帮助!!

<?php

$servername = "localhost";
$username = "username";
$password = "";
$dbname = "database";

// Create connection
$conn = new mysqli($servername, $username, $password, $dbname);
// Check connection
if ($conn->connect_error) {
    die("Connection failed: " . $conn->connect_error);
} 
echo "Connected successfully";

$sql_light = mysqli_query("SELECT light FROM bot_command WHERE cmd_id = '1'");
$result_light = mysql_fetch_assoc($sql_light);

if (isset($result_light['light']) && $row['light'] == 1) {
    $sql = "UPDATE bot_command SET light='0' WHERE cmd_id = '1'";
    $result = $conn->query($sql);
    // output data of each row
    while($row = $result_select->fetch_assoc()) {
        echo " - Light: " . $row["light"]."<br>";       
    }
} else {
    echo "0 results";
}




if ($conn->query($sql) === TRUE) {
    echo " - Record updated successfully";
} else {
    echo " - Error updating record: " . $conn->error;
}

$conn->close();

//$sql = "SELECT light FROM bot_command WHERE cmd_id = '1'";

?>

Answer 1

在一个查询中有一个老技巧：

UPDATE `tablename` SET `field` = 1 - `field`

这种情况如果field == 1它将变为0，如果它是0，它将成为1

Answer 2

使用MySQL的IF：

UPDATE bot_command 
SET light=IF( light=1, 0, 1)
WHERE cmd_id = '1';

Answer 3

你应该这样写：

$sql_light = mysqli_query($con,"SELECT light FROM bot_command WHERE cmd_id = '1'");

if(mysqli_num_rows($sql_light)>0){
    $result_light = mysqli_fetch_assoc($sql_light);
    if($result_light['light']=="0"){
        $sql = "UPDATE bot_command SET light='1' WHERE cmd_id = '1'";
    }else{
        $sql = "UPDATE bot_command SET light='0' WHERE cmd_id = '1'";
    }
    $result = mysqli_query($sql);
    if($result){
         echo "Updated..";
    }else{
         echo "Not Updated..";
    }
}

Answer 4

UPDATE table SET value = ABS(value - 1)

简单而有效。

这会将所有1更改为：1 - 1 = 0，将所有0更改为绝对值：0 - 1 = -1，ABS(-1) = 1

检查MySQL字段值是否等于某个数字

4 个答案: