在运行SQL之前生成WHERE子句.

Generate the WHERE clause prior to running the SQL.

一个简短的例子:

$whereClause = "";

if ($_POST['opt1']) {
    $opt1 = mysql_real_escape_string($_POST['opt1']);
    $whereClause .= "AND opt1='$opt1'";
}

if ($_POST['opt2']) {
    $opt2 = mysql_real_escape_string($_POST['opt2']);
    $whereClause .= "AND opt2='$opt2'";
}

mysql_query("SELECT * FROM table WHERE 1 ".$whereClause);