PHP MySQL- 根据 GET 变量更改 Where 语句

Question

您好，我有一个表，我想在这个表上应用 4-5 个 sql 选择查询

表格

id     name      product       price

1      Amit      car           100000
2      Sumit     car           300000
3      Naina     car           250000
4      Ashu      car           125000
5      Sanjay    scooter        40000
6      Rahul     scooter        32000

我想在此表上应用 4-5 个查询，例如首先我想获取产品 = 汽车的所有结果

查询 1:

SELECT * FROM Table WHERE product='car'

URL:  www.example.com/product/car

输出:

id     name      product       price

1      Amit      car           100000
2      Sumit     car           300000
3      Naina     car           250000
4      Ashu      car           125000

查询2:

SELECT * FROM Table WHERE product='car' ORDER BY price

URL:  www.example.com/product/car?sort=plth

输出:

id     name      product       price

1      Amit      car           100000
4      Ashu      car           125000
3      Naina     car           250000
2      Sumit     car           300000

查询 3:

SELECT * FROM Table WHERE product='car' ORDER BY price DESC

URL:  www.example.com/product/car?sort=phtl

输出:

id     name      product       price

2      Sumit     car           300000
3      Naina     car           250000
4      Ashu      car           125000
1      Amit      car           100000

是否可以预先声明一个if else语句，在sql语句中使用一个变量，写一次select语句。

喜欢

$where="WHERE product='car'";

if(isset($_GET['sort'])){
  if(($_GET['sort'])=='plth'){
    $where="WHERE product='car' ORDER BY price"
  }
  elseif($_GET['sort'])=='phtl'){
    $where="WHERE product='car' ORDER BY price DESC"
  }
  ------
  ------
  ------
}

查询如下:

SELECT * FROM Table $where;

提前致谢...

Answer 1

您将使用准备好的语句并绑定(bind)变量。至于升序还是降序这就不太容易了，因为ASC和DESC是关键字，绑定(bind)变量只能用于列值，不能用于关键字。但是，按价格降序排序与按 price * -1 排序相同 :-)

$product = "car";
$order = "DESC";

$pdo = new PDO("mysql:host=localhost;dbname=database", "username", "password");
$stmt = $pdo->prepare("select * " .
                      "from table " .
                      "where product = :product " .
                      "order by price * case when :order = 'DESC' then -1 else 1 end ");
$stmt->bindParam(':product', $product, PDO::PARAM_STR, 12);
$stmt->bindParam(':order', $order, PDO::PARAM_STR);
$stmt->execute();

或者，如果您觉得 CASE WHEN 不可读，请使用

$order = -1;
...
              "order by price * :order ");
...
$stmt->bindParam(':order', $order, PDO::PARAM_INT);