php - 提交空搜索字段时如何停止搜索字段返回所有结果？

Question

如果我单击我的搜索字段并在不输入任何文本的情况下提交它，则会返回我数据库中的所有数据。这是如何停止的，所以什么也没有发生？

查看网站:

weezy.co.uk/newresults.php

谢谢!

詹姆斯

 <?php

    $conn = mysql_connect("cust-mysql-123-02", "uwee_641290_0001", "La0%-Mr4");

    if (!$conn) {
    echo "Unable to connect to DB: " . mysql_error();
    exit;
    }

    {

      $search = "%" . $_POST["search"] . "%";
    $searchterm = "%" . $_POST["searchterm"] . "%";

    }

    if (!mysql_select_db("weezycouk_641290_db1")) {
    echo "Unable to select mydbname: " . mysql_error();
    exit;
    }

    $sql = "SELECT name,lastname,email 
    FROM   test_mysql
    WHERE  name LIKE '%".$search."%' AND lastname LIKE '%".$searchterm."%'";

    $result = mysql_query($sql);

    if (!$result) {
    echo "Could not successfully run query ($sql) from DB: " . mysql_error();
    exit;
    }

    if (mysql_num_rows($result) == 0) {
    echo "No rows found, nothing to print so am exiting";
    exit;
    }


while ($row = mysql_fetch_assoc($result)) {
    echo '<br>';
    echo '<br>';
    echo '<div class="data1">';
    echo $row["name"];
    echo '</div>';
    echo '<br>';
    echo '<div class="data2">';
    echo $row["lastname"];
    echo '</div>';
    echo '<br>';
    echo '<div class="data3">';
    echo $row["email"];
    echo '</div>';
    }

    mysql_free_result($result);

    ?>

Answer 1

你应该在进行查询之前检查它是否为空:

if(empty($_POST['searchterm'])){
    //don't search and show an error message
}else{
   //proceed as normal, do the query
}

否则您最终可能会进行如下查询:

WHERE name LIKE('%%')

这真的很昂贵并返回所有数据库行