显示存储在 MYSQL 数据库中的逗号分隔字符串中唯一的第一项

Question

<ul class="p-b-54">
    <li class="p-t-4">
        <a href="#" class="s-text13 active1">
        All
        </a>
    </li>
    <?php 
    $category_query_sql = "SELECT DISTINCT `Category` FROM `laptops`  ORDER BY `Id` DESC LIMIT 100 ";
    $run_query_category = mysqli_query($con,$category_query_sql) or die(mysqli_error($con));
    if(mysqli_num_rows($run_query_category) > 0){
        while($row = mysqli_fetch_array($run_query_category)){
            $product_Category = $row["Category"];                
    ?>

    <li class="p-b-9">
        <a href="#" class="s-text7">
        <?php 
        $prod_Cat = explode(", ", $product_Category);
        echo $prod_Cat[0]; 
        ?>
        </a>
    </li>
<?php 
        }
    }
?>
</ul>

这是它们在数据库中的保存方式

Electronics, Computers & Accessories, Computers & Tablets, Laptops, Traditional Laptops
Electronics, Computers & Accessories, Computers & Tablets
Electronics, Computers & Accessories, Computers & Tablets, Laptops, 2 in 1 Laptops
Electronics, Computers & Accessories, Computers & Tablets, Tablets
Electronics, Computers & Accessories, Monitors
Electronics, Accessories & Supplies, Audio & Video Accessories, TV Accessories & Parts, TV Ceiling & Wall Mounts
Electronics, Accessories & Supplies, Audio & Video Accessories
Electronics, Camera & Photo, Digital Cameras, DSLR Cameras
Electronics, Television & Video, Televisions
Electronics, PC Gaming, Gaming Computers
Gaming Monitors
Gaming Laptops

这就是我所期待的

Electronics
Gaming Monitors
Gaming Laptops

我想摆脱所有重复的电子产品

到目前为止我的输出是

Electronics
Electronics
Electronics
Electronics
Electronics
Electronics
Electronics
Electronics
Electronics
Electronics
Gaming Monitors
Gaming Laptops

我有一个类别列表存储在 mysql 数据库中，用逗号分隔单词。我已经设法显示每个字符串的第一个单词。尽管我的意图是在提取第一个单词后获得独特的类别。但是正如您所看到的，我正在获取所有重复的内容。我该如何摆脱它们？

如果你想创建 TABLE 这就是 SQL 查询

-- --------------------------------------------------------

--
-- Table structure for table `gaminglaptops`
--

CREATE TABLE `gaminglaptops` (
  `Id` int(11) NOT NULL,
  `Category` text NOT NULL,
) ENGINE=InnoDB DEFAULT CHARSET=latin1;

--
-- Dumping data for table `gaminglaptops`
--

INSERT INTO `gaminglaptops` (`Category`) VALUES
('Gaming Laptops'),
('Electronics, PC Gaming, Gaming Computers'),
('Gaming Monitors'),
('Electronics, Television & Video, Televisions'),
('Electronics, Camera & Photo, Digital Cameras, DSLR Cameras'),
('Electronics, Accessories & Supplies, Audio & Video Accessories, TV Accessories & Parts, TV Ceiling & Wall Mounts'),
('Electronics, Accessories & Supplies, Audio & Video Accessories'),
('Electronics, Computers & Accessories, Monitors'),
('Electronics, Computers & Accessories, Computers & Tablets, Tablets'),
('Electronics, Computers & Accessories, Computers & Tablets, Laptops, 2 in 1 Laptops'),
('Electronics, Computers & Accessories, Computers & Tablets'),
('Electronics, Computers & Accessories, Computers & Tablets, Laptops, Traditional Laptops');

--
-- Indexes for dumped tables
--

--
-- Indexes for table `gaminglaptops`
--
ALTER TABLE `gaminglaptops`
  ADD PRIMARY KEY (`Id`),

Answer 1

尝试使用 continue 语句

<ul class="p-b-54">
    <li class="p-t-4">
        <a href="#" class="s-text13 active1">
        All
        </a>
    </li>
    <?php 
    $cat_name = "";
    $category_query_sql = "SELECT DISTINCT `Category` FROM `laptops`  ORDER BY `Id` DESC LIMIT 100 ";
    $run_query_category = mysqli_query($con,$category_query_sql) or die(mysqli_error($con));
    if(mysqli_num_rows($run_query_category) > 0){
        while($row = mysqli_fetch_array($run_query_category)){
            $product_Category = $row["Category"];                
    ?>

    <li class="p-b-9">
        <a href="#" class="s-text7">
        <?php 
        $prod_Cat = explode(", ", $product_Category);
        if($cat_name == $prod_Cat[0]){
            continue;
        }else{
            $catname = $prod_Cat[0];
        }
        echo $catname;
        ?>
        </a>
    </li>
<?php 
        }
    }
?>
</ul>

Answer 2

您可以稍微更改查询以 return 个独特的结果。

使用SUBSTRING_INDEX提取第一个值，

SUBSTRING_INDEX('Electronics, PC Gaming, Gaming Computers', ',', 1)

将 return Electronics.

然后对您的查询进行区分，

SELECT DISTINCT(SUBSTRING_INDEX(`Category`, ',', 1)) AS Cat
FROM `laptops`
ORDER BY `Id`
DESC LIMIT 100

现在查询将 return 唯一的结果，只有一个值。因此，您可以消除在循环中分解结果的需要。优化了下面的代码段，

<?php
while($row = mysqli_fetch_array($run_query_category)) {
?>
<li class="p-b-9">
    <a href="#" class="s-text7"><?php echo $row["Cat"]; ?></a>
</li>
<?php 
}

Answer 3

最简单的方法可能是创建一个空数组（例如 $uniqueElements），在 for 循环中迭代每个元素并通过使用 [=12 检查内容将每个唯一项推入空数组=]($元素，$uniqueElements)。

Answer 4

你应该把所有的第一个单词保存在一个数组中，在开始时实例化，比如

$first_categories = [];

然后，为了简单起见，在每次迭代中，您可以将值附加到数组中，例如

$first_categories[] = $prod_Cat[0];

并得到一个只有唯一值的新数组

$unique_first_categories = array_unique($first_categories);

Answer 5

您可以尝试将其保存为数组并检查是否存在

<ul class="p-b-54">
    <li class="p-t-4">
        <a href="#" class="s-text13 active1">
        All
        </a>
    </li>
    <?php 
        $cat_name = "";
        $allCat = array();
        $category_query_sql = "SELECT DISTINCT `Category` FROM `laptops`  ORDER BY `Id` DESC LIMIT 100 ";
        $run_query_category = mysqli_query($con,$category_query_sql) or die(mysqli_error($con));
        if(mysqli_num_rows($run_query_category) > 0){
            while($row = mysqli_fetch_array($run_query_category)){
                $product_Category = $row["Category"];
                $prod_Cat = explode(", ", $product_Category);

                if(!in_array($prod_Cat[0], $allCats) { // if not yet exist in array
                     // push to allCats (unique)
                     array_push($allCats, $prodCat[0]);
                    // display
                    ?>

                    <li class="p-b-9">
                        <a href="#" class="s-text7">
                        <?php 
                            echo end($allCats); // last item pushed
                        ?>
                        </a>
                    </li>
                    <?php 
                }
            }
        }
    ?>
</ul>

Answer 6

我的回答更新了

<li class="p-b-9">
    <a href="#" class="s-text7">
    <?
        echo end($allCats); // last item 
    ?>
    </a>
</li>

显示存储在 MYSQL 数据库中的逗号分隔字符串中唯一的第一项

Displaying Unique First Item From Comma Separated Strings Stored In MYSQL Database

php

unique

categories