Commonly used functions for obtaining SQL query results in PHP (detailed examples)

In the previous article, I brought you "Usage of mysqli_select_db and mysqli_query functions in PHP", which gave you a detailed introduction to how to use the two functions and their main functions. In this article, we continue to look at how to obtain SQL query results in PHP. I hope everyone has to help!

In the previous article, we talked about how to execute a SQL statement, which is to call the mysqli_query() function. Through this function we can already The database information has been queried, but in our daily development we still need to process the result to get the information we want. Next, let’s take a look at several functions commonly used to process results in PHP.

<strong><span style="font-size: 20px;">mysqli_fetch_row()</span></strong> function

mysqli_fetch_row() function You can get a row from the result set and return it in the form of an index array. The syntax format is as follows:

mysqli_result::fetch_row()

This is object-oriented writing, and the process-oriented writing is as follows:

mysqli_fetch_row(mysqli_result $result)

You need to pay attention to it are: mysqli_result and $result are represented as the result set obtained using the mysqli_query() function.

Next let’s take a look at the usage of the mysqli_fetch_row() function through an example. The example is as follows:

<?php
    $host     = &#39;localhost&#39;;
    $username = &#39;root&#39;;
    $password = &#39;root&#39;;
    $dbname   = &#39;test&#39;;
    $mysql    = new Mysqli($host, $username, $password, $dbname);
    if($mysql -> connect_errno){
        die(&#39;数据库连接失败：&#39;.$mysql->connect_errno);
    }else{
        $sql    = &#39;select name,sex,age from user&#39;;     // SQL 语句
        $result = $mysql -> query($sql);               // 执行上面的 SQL 语句
        $data   = $result -> fetch_row();
        $mysql -> close();
    }
    echo &#39;<pre class="brush:php;toolbar:false">&#39;;
    print_r($data);
?>

Output result:

In the above example, one row of data in the database is successfully queried through the mysqli_fetch_row() function, and is returned in the form of an index array. Then let's take a look at the different return forms.

<strong><span style="font-size: 20px;">mysqli_fetch_assoc()</span></strong> function

mysqli_fetch_assoc() function You can get a row from the result set and return it in the form of an associative array. The syntax format of this function is as follows:

mysqli_result::fetch_assoc()

This is its object-oriented syntax format, and the following is its procedural-oriented syntax format:

mysqli_fetch_assoc(mysqli_result $result)

It should be noted that: mysqli_result and $result are represented as result sets obtained using the mysqli_query() function.

Next let’s look at the use of the mysqli_fetch_assoc() function through an example. The example is as follows:

<?php
    $host     = &#39;localhost&#39;;
    $username = &#39;root&#39;;
    $password = &#39;root&#39;;
    $dbname   = &#39;test&#39;;
    $link     = @mysqli_connect($host, $username, $password, $dbname);
    if($link){
        $sql    = &#39;select name,sex,age from user&#39;;  // SQL 语句
        $result = mysqli_query($link, $sql);        // 执行 SQL 语句，并返回结果
        $data   = mysqli_fetch_assoc($result);      // 从结果集中获取一条数据
        mysqli_close($link);
    }else{
        echo &#39;数据库连接失败！&#39;;
    }
    echo &#39;<pre class="brush:php;toolbar:false">&#39;;
    print_r($data);
?>

Output result:

From the above example, we successfully obtained a row of information in the database through the mysqli_fetch_assoc() function and returned it through an associative array. We can also control the form of the returned data through a function, so that it can be an index array, an associative array, or a combination of both. In this case, we will use the mysqli_fetch_array() function.

<strong><span style="font-size: 20px;">mysqli_fetch_array()</span></strong> function

mysqli_fetch_array() function You can get a row from the result set and return it in the form of an associative array, an index array, or both according to the parameters. Its syntax format is as follows:

mysqli_result::fetch_array([int $resulttype = MYSQLI_BOTH])

This is an object-oriented syntax, and the following is process-oriented The syntax:

mysqli_fetch_array(mysqli_result $result[, int $resulttype = MYSQLI_BOTH])

It should be noted that:

• ##mysqli_result and $result are expressed as The result set obtained using the mysqli_query() function.

• $resulttype is an optional parameter. It is a constant used to set the type of return value. Its value can be MYSQLI_ASSOC, MYSQLI_NUM or MYSQLI_BOTH indicates different types of return values.

Next let’s take a look at the usage of the mysqli_fetch_array() function through an example. The example is as follows:

<?php
    $host     = &#39;localhost&#39;;
    $username = &#39;root&#39;;
    $password = &#39;root&#39;;
    $dbname   = &#39;test&#39;;
    $link     = @mysqli_connect($host, $username, $password, $dbname);
    if($link){
        $sql    = &#39;select name,sex,age from user&#39;;          // SQL 语句
        $result = mysqli_query($link, $sql);                // 执行 SQL 语句，并返回结果
        $data   = mysqli_fetch_array($result, MYSQLI_ASSOC);// 从结果集中获取所有数据
        mysqli_close($link);
    }else{
        echo &#39;数据库连接失败！&#39;;
    }
    echo &#39;<pre class="brush:php;toolbar:false">&#39;;
    print_r($data);
?>

Output result:

In the above example, we chose to return data in the form of an associative array. We can choose different types of return values ​​through the mysqli_fetch_array() function.

<strong>mysqli_fetch_all() <span style="font-size: 20px;"></span></strong>Function

mysqli_fetch_all() function You can get all the data in the result set and return it in the form of an associative array, an index array, or both according to the parameters. Its syntax format is as follows:

mysqli_result::fetch_all([int $resulttype = MYSQLI_NUM])

This is object-oriented writing, and the following is process-oriented The writing method:

mysqli_fetch_all(mysqli_result $result [, int $resulttype = MYSQLI_NUM])

It should be noted that: the syntax is the same as the mysqli_fetch_array() function

• ##mysqli_resul

  t and $result Represented as a result set obtained using the mysqli_query() function.

• $resulttype 为可选参数，它是一个常量，用来设定返回值的类型，它的取值可以是 MYSQLI_ASSOC、MYSQLI_NUM 或 MYSQLI_BOTH表示返回值的不同类型。

接下来通过示例来看一下mysqli_fetch_all() 函数的使用，示例如下：

<?php
    $host     = &#39;localhost&#39;;
    $username = &#39;root&#39;;
    $password = &#39;root&#39;;
    $dbname   = &#39;test&#39;;
    $mysql    = new Mysqli($host, $username, $password, $dbname);
    if($mysql -> connect_errno){
        die(&#39;数据库连接失败：&#39;.$mysql->connect_errno);
    }else{
        $sql    = &#39;select name,sex,age from user&#39;;     // SQL 语句
        $result = $mysql -> query($sql);               // 执行上面的 SQL 语句
        $data   = $result -> fetch_all(MYSQLI_ASSOC);
        $mysql -> close();
    }
    echo &#39;<pre class="brush:php;toolbar:false">&#39;;
    print_r($data);
?>

输出结果：

上述示例中，便是通过mysqli_fetch_all() 函数选择以关联数组的形式返回所有的数据。

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