Question

我有一串值，如：

$cat = "1,5,6,8,9";

现在我想在WHERE子句中使用该变量。我该怎么做？

"select category from test where category...?"

我正在使用下面的代码，但是我从number_of_result变量得到null：

$array_of_cat = explode(",",$cat);

if($number_of_result == 0){
    $mresult = mysql_query("select * from books where
     GoodName like '%$title%' and GroupCode in ($array_of_cat) ");
    $number_of_result = mysql_num_rows($mresult);
}

Answer 1

您不需要爆炸变量 - 这样做会导致数组在插入SQL字符串时导致错误的值（字符串＆＃34;数组＆＃34;）。

尽管这是不安全的（SQL injection prone），但您可以这样做：

if($number_of_result == 0){
    $mresult = mysql_query("select * from books where
     GoodName like '%$title%' and GroupCode in ($cat)");
    $number_of_result = mysql_num_rows($mresult);
}

我强烈建议您使用mysql_real_escape_string函数来准备变量。

Answer 2

将您的SQL语句更改为此语句。使用implode()传递IN子句

中的数组元素

$mresult = mysql_query("
  SELECT * FROM books 
  WHERE GoodName LIKE '%$title%' AND GroupCode IN (" . implode(",", $array_of_cat) . ")");

Answer 3

$cat = array(1,5,6,8,9);

$array_of_cat = implode(",",$cat);

if($number_of_result > 0){
  $mresult = mysql_query("select * from books where
  GoodName like '%$title%' and GroupCode in ($array_of_cat) ");

$number_of_result = mysql_num_rows($mresult);
}

此外，我强烈建议您阅读PDO / MySQLi

在WHERE子句中使用一串值 - mysql

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