SQL查询失败

Question

我希望查询最初返回c_id>0所在位置的所有记录，然后根据通过文本框提供的后续条件进行过滤。但是，在第一次访问页面时，我不会打印任何记录。代码如下：

$ctitle = mysql_real_escape_string($_POST['ctitle']);
$csubject = mysql_real_escape_string($_POST['csubject']);
$creference = mysql_real_escape_string($_POST['creference']);
$cobjecttype = mysql_real_escape_string($_POST['cobjecttype']);
$cmaterial = mysql_real_escape_string($_POST['cmaterial']);
$ctechnic = mysql_real_escape_string($_POST['ctechnic']);
$cartist = mysql_real_escape_string($_POST['cartist']);
$csource = mysql_real_escape_string($_POST['csource']);

    $sql = "SELECT * FROM collections WHERE (
    c_id>0 AND
    `ctitle` LIKE '{$ctitle}' AND
    `csubject` LIKE '{$csubject}' AND
    `creference` LIKE '{$creference}' AND
    `cobjecttype` LIKE '{$cobjecttype}' AND
    `cmaterial` LIKE '{$cmaterial}' AND
    `ctechnic` LIKE '{$ctechnic}' AND
    `csource` LIKE '{$csource}' AND
    `cartist` LIKE '{$cartist}'
    )ORDER BY c_id DESC";

当我回显查询时，我会打印以下内容：

request "Could not execute SQL query" SELECT * FROM collections WHERE ( c_id>0 AND `ctitle` LIKE '' AND `csubject` LIKE '' AND `creference` LIKE '' AND `cobjecttype` LIKE '' AND `cmaterial` LIKE '' AND `ctechnic` LIKE '' AND `csource` LIKE '' AND `cartist` LIKE '' )ORDER BY c_id DESC

从这里我应该去哪里？

Answer 1

在)和ORDER BY之间加一个空格

Answer 2

两个where子句元素前后不需要大括号。

Answer 3

好的..。我想我明白了..。尝试将LIKE ''替换为LIKE '%'

LIKE ''将不起作用，因为它只显示空列。通过添加一个通配符 (%)，它将显示与所有内容匹配的所有行。但是，完全动态构建查询，省略空的WHERE条件，可能是一种更好、更简洁的解决方案。