插入前检查重复项

Question

在插入数据库之前,我使用以下代码来检查重复项.对我来说,重复的只考虑重复时name,description,price,city,和enddate比赛.

foreach($states_to_add as $item) {
    $dupesql = "SELECT 
                    COUNT(*) 
                FROM 
                    table 
                WHERE 
                    (   
                        name = '$name' 
                        AND description = '$description' 
                        AND manufacturer = '$manufacturer' 
                        AND city ='$city' 
                        AND price = '$price' 
                        AND enddate = '$end_date'
                    )";

    $duperaw = mysql_query($dupesql);

    if($duperaw > 0) {
        echo nl2br("$name already exists in $city \n");
    } 
    else {
        $sql = "INSERT INTO table (..... (here go the values to be inserted)
        ....

在运行此检查之前定义每个值,我的结果总是在项目已存在时返回.我倾倒了"dupesql"并将命令复制/粘贴到phpmyadmin中,后者返回计数0.

Answer 1

您想要执行以下操作:

$dupesql = "SELECT * FROM table where (name = '$name' AND description = '$description' AND manufacturer = '$manufacturer' AND city ='$city' AND price = '$price' AND enddate = '$end_date')";

$duperaw = mysql_query($dupesql);

if (mysql_num_rows($duperaw) > 0) {
  //your code ...
}

有关更多信息,请参见此处

Answer 2

我认为你的问题可以分为两部分.为什么我的PHP代码不起作用？我不知道,不知道PHP和其他人似乎刚刚回答:-).第二个问题是我如何检查重复？你正在以完全错误的方式检查重复项.

在表上创建唯一的索引/主键.然后,当您尝试插入数据库时​​,如果存在重复,则会抛出错误.捕获错误并按照您的需要处理它.计算记录数绝对是错误的方法,这将严重损害您的代码速度.