在插入之前檢查值，如果已經存在，請不要使用 php 在 mysql 上插入它

Question

我有代碼檢查 ips 地址，如果重復將重定向到另一個鏈接，但是當第一次在表（ click ）中插入值（ ip,user_agent,time ）時代碼運行良好，但是當我嘗試檢查是否使用某些寫入的值運行時再次在數據庫上我需要任何值（ ip,user_agent,time ）在寫入數據庫后僅寫入一次而不是寫入某些值（ ip,user_agent,time ）

<?php
    $servername = "localhost";
    $username = "root";
    $password = "rootroot";
    $dbname = "data_clicks";
    //Create connection to database using mysqli
    $conn = new mysqli($servername, $username , $password, $dbname);



    //Set variables according to user input on previous form
    if(isset($_SERVER['REMOTE_ADDR']) && isset($_SERVER['HTTP_USER_AGENT'])){
        $ip = $_SERVER['REMOTE_ADDR'];
        $user = $_SERVER['HTTP_USER_AGENT'];
        $datetime = date_create()->format('d-m-Y ');
    }


    //Define the INSERT statement with IGNORE keyword
        $sql = "INSERT IGNORE INTO clicks (ip, user_agent, time )
        VALUES ('.$ip.', '.$user.', CURRENT_TIMESTAMP)";
        if ($conn->query($sql) === false) {
            die("Database error:".$conn->error);
        }
    // link offer
    $file = "md5.txt";
    $f = fopen($file, 'r');
    $line = fgets($f);
    fclose($f);
    $link="https://facebook.com/?".$line;
    //do smth

    $contents = file($file, FILE_IGNORE_NEW_LINES);
    $first_line = array_shift($contents);
    file_put_contents($file, implode("\r\n", $contents));

    // Check for success
        if ($conn->affected_rows == 0) {
            print "<br>Error! <p></p>";
            echo "" . $ip .''.$user. " already exists in the DCR";
            header("Location: http://www.google.com/");
        } else {

    //Success and return new id
            echo "<br><p></p>Record Added!<p></p>";
            header("Location: $link");
        }
    ?> 

Answer 1

我有代碼檢查 ips 地址，如果重復將重定向到另一個鏈接，但是當第一次在表（ click ）中插入值（ ip,user_agent,time ）時代碼運行良好，但是當我嘗試檢查是否使用某些寫入的值運行時再次在數據庫上我需要任何值（ ip,user_agent,time ）在寫入數據庫后僅寫入一次而不是寫入某些值（ ip,user_agent,time ）

<?php
    $servername = "localhost";
    $username = "root";
    $password = "rootroot";
    $dbname = "data_clicks";
    //Create connection to database using mysqli
    $conn = new mysqli($servername, $username , $password, $dbname);



    //Set variables according to user input on previous form
    if(isset($_SERVER['REMOTE_ADDR']) && isset($_SERVER['HTTP_USER_AGENT'])){
        $ip = $_SERVER['REMOTE_ADDR'];
        $user = $_SERVER['HTTP_USER_AGENT'];
        $datetime = date_create()->format('d-m-Y ');
    }


    //Define the INSERT statement with IGNORE keyword
        $sql = "INSERT IGNORE INTO clicks (ip, user_agent, time )
        VALUES ('.$ip.', '.$user.', CURRENT_TIMESTAMP)";
        if ($conn->query($sql) === false) {
            die("Database error:".$conn->error);
        }
    // link offer
    $file = "md5.txt";
    $f = fopen($file, 'r');
    $line = fgets($f);
    fclose($f);
    $link="https://facebook.com/?".$line;
    //do smth

    $contents = file($file, FILE_IGNORE_NEW_LINES);
    $first_line = array_shift($contents);
    file_put_contents($file, implode("\r\n", $contents));

    // Check for success
        if ($conn->affected_rows == 0) {
            print "<br>Error! <p></p>";
            echo "" . $ip .''.$user. " already exists in the DCR";
            header("Location: http://www.google.com/");
        } else {

    //Success and return new id
            echo "<br><p></p>Record Added!<p></p>";
            header("Location: $link");
        }
    ?>