PHP MySQL 读取数据

实例 (MySQLi - 面向对象)

$servername = " localhost " ; $username = " username " ; $password = " password " ; $dbname = " myDB " ; // 创建连接 $conn = new mysqli ( $servername , $username , $password , $dbname ) ; // Check connection if ( $conn -> connect_error ) { die ( " 连接失败: " . $conn -> connect_error ) ; $sql = " SELECT id, firstname, lastname FROM MyGuests " ; $result = $conn -> query ( $sql ) ; if ( $result -> num_rows > 0 ) { // 输出数据 while ( $row = $result -> fetch_assoc ( ) ) { echo " id: " . $row [ " id " ] . " - Name: " . $row [ " firstname " ] . " " . $row [ " lastname " ] . " <br> " ; } else { echo " 0 结果 " ; $conn -> close ( ) ;

以上代码解析如下:

首先，我们设置了 SQL 语句从 MyGuests数据表中读取 id, firstname 和 lastname 三个字段。之后我们使用该 SQL 语句从数据库中取出结果集并赋给复制给变量 $result。

函数 num_rows() 判断返回的数据。

如果返回的是多条数据，函数 fetch_assoc() 将结合集放入到关联数组并循环输出。 while() 循环出结果集，并输出 id, firstname 和 lastname 三个字段值。

以下实例使用 MySQLi 面向过程的方式，效果类似以上代码:

实例 (MySQLi - 面向过程)

$servername = " localhost " ; $username = " username " ; $password = " password " ; $dbname = " myDB " ; // 创建连接 $conn = mysqli_connect ( $servername , $username , $password , $dbname ) ; // Check connection if ( ! $conn ) { die ( " 连接失败: " . mysqli_connect_error ( ) ) ; $sql = " SELECT id, firstname, lastname FROM MyGuests " ; $result = mysqli_query ( $conn , $sql ) ; if ( mysqli_num_rows ( $result ) > 0 ) { // 输出数据 while ( $row = mysqli_fetch_assoc ( $result ) ) { echo " id: " . $row [ " id " ] . " - Name: " . $row [ " firstname " ] . " " . $row [ " lastname " ] . " <br> " ; } else { echo " 0 结果 " ; mysqli_close ( $conn ) ; echo " <table style='border: solid 1px black;'> " ; echo " <tr><th>Id</th><th>Firstname</th><th>Lastname</th></tr> " ; class TableRows extends RecursiveIteratorIterator { function __construct ( $it ) { parent :: __construct ( $it , self :: LEAVES_ONLY ) ; function current ( ) { return " <td style='width:150px;border:1px solid black;'> " . parent :: current ( ) . " </td> " ; function beginChildren ( ) { echo " <tr> " ; function endChildren ( ) { echo " </tr> " . " \n " ; $servername = " localhost " ; $username = " username " ; $password = " password " ; $dbname = " myDBPDO " ; try { $conn = new PDO ( " mysql:host= $servername ;dbname= $dbname " , $username , $password ) ; $conn -> setAttribute ( PDO :: ATTR_ERRMODE , PDO :: ERRMODE_EXCEPTION ) ; $stmt = $conn -> prepare ( " SELECT id, firstname, lastname FROM MyGuests " ) ; $stmt -> execute ( ) ; // 设置结果集为关联数组 $result = $stmt -> setFetchMode ( PDO :: FETCH_ASSOC ) ; foreach ( new TableRows ( new RecursiveArrayIterator ( $stmt -> fetchAll ( ) ) ) as $k => $v ) { echo $v ; catch ( PDOException $e ) { echo " Error: " . $e -> getMessage ( ) ; $conn = null ; echo " </table> " ;