How to return the query value in HTML form in php

In the process of website development, we often need to query some information from the database and then display this information to the user. In some cases, we need to return the query results in HTML form. In this case, we need to use PHP to implement it.

In PHP, we can use the mysqli library to connect to the database and query the required data. First, we need to connect to the database through the mysqli_connect() function, as shown below:

$servername = "localhost";     // 数据库地址
$username = "username";        // 数据库用户名
$password = "password";        // 数据库密码
$dbname = "myDB";              // 数据库名称

// 创建连接
$conn = mysqli_connect($servername, $username, $password, $dbname);

// 检测连接
if (!$conn) {
    die("Connection failed: " . mysqli_connect_error());
}

Next, we can use the mysqli_query() function to execute the query statement and return the result to a variable, as shown below Display:

$sql = "SELECT * FROM myTable";
$result = mysqli_query($conn, $sql);

After getting the query results, we need to output them in HTML. At this time, you can use the echo statement to output HTML code. In the process of outputting HTML code, we can use loop statements to traverse each row of data and wrap it in HTML tags, as shown below:

echo "<table>";
while($row = mysqli_fetch_assoc($result)) {
    echo "<tr>";
    echo "<td>" . $row["id"]. "</td>";
    echo "<td>" . $row["name"]. "</td>";
    echo "<td>" . $row["email"]. "</td>";
    echo "</tr>";
}
echo "</table>";

This code is used to output a query result HTML table. In the loop, we use the mysqli_fetch_assoc() function to get a row of data and then output it to the corresponding cell of the HTML table.

In addition to using loop statements, we can also use conditional statements to output different HTML codes based on query results. For example, we can output different prompt information based on the number of query results, as shown below:

if (mysqli_num_rows($result) == 0) {
    echo "没有记录";
} else {
    echo "查询结果如下：";
    echo "<table>";
    while($row = mysqli_fetch_assoc($result)) {
        echo "<tr>";
        echo "<td>" . $row["id"]. "</td>";
        echo "<td>" . $row["name"]. "</td>";
        echo "<td>" . $row["email"]. "</td>";
        echo "</tr>";
    }
    echo "</table>";
}

In this code, we use the mysqli_num_rows() function to get the number of query results, and then based on the number of results Make different outputs.

When using PHP to output HTML code, we need to pay attention to the following points:

1. When outputting HTML tags, you need to use double quotes instead of single quotes.
2. When outputting complex HTML structures such as tables, you can use indentation and line breaks to make the code clearer and easier to read.
3. When outputting HTML code, you need to avoid outputting duplicate code snippets. You can extract the same code snippets as functions or variables.

In short, in website development, it is a common operation to use PHP to query the database and return the results in HTML form. Mastering this skill will not only help develop richer and more flexible websites, but also help improve our programming capabilities and efficiency.

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