A brief introduction to the definition method and usage of the pdo public class in php

This article mainly introduces the definition and usage of the pdo public class implemented by PHP. It analyzes the PDO operation class definition and query, insertion and other usage techniques implemented by PHP based on specific examples. Friends in need can refer to it

The example in this article describes the definition and usage of the pdo public class implemented by PHP. Share it with everyone for your reference, the details are as follows:

db.class.php:

<?php
class db extends \PDO {
  private static $_instance = null;
  protected $dbName = &#39;&#39;;
  protected $dsn;
  protected $dbh;
  public function __construct($dbHost, $dbUser, $dbPasswd, $dbName, $dbCharset=&#39;utf8&#39;) {
    try {
      $this->dsn = &#39;mysql:host=&#39; . $dbHost . &#39;;dbname=&#39; . $dbName;
      $this->dbh = new \PDO($this->dsn, $dbUser, $dbPasswd);
      $this->dbh->setAttribute(\PDO::ATTR_EMULATE_PREPARES, false);
      $this->dbh->setAttribute(\PDO::ATTR_ERRMODE, \PDO::ERRMODE_EXCEPTION);
      $this->dbh->exec(&#39;SET character_set_connection=&#39;.$dbCharset.&#39;;SET character_set_client=&#39;.$dbCharset.&#39;;SET character_set_results=&#39;.$dbCharset);
    } catch (Exception $e) {
      $this->outputError($e->getMessage()); 
    }
  }
  public static function getInstance($dbHost, $dbUser, $dbPasswd, $dbName, $dbCharset=&#39;utf8&#39;) {
    if (self::$_instance === null) {
      self::$_instance = new self($dbHost, $dbUser, $dbPasswd, $dbName, $dbCharset);
    }
    return self::$_instance;
  }
  public function fetchAll($sql, $params = array()) {
    try {
      $stm = $this->dbh->prepare($sql);
      if ($stm && $stm->execute($params)) {
        return $stm->fetchAll(\PDO::FETCH_ASSOC);
      }
    } catch (Exception $e) {
      $this->outputError($e->getMessage());
    }
  }
  public function fetchOne($sql, $params = array()) {
    try {
      $result = false;
      $stm = $this->dbh->prepare($sql);
      if ($stm && $stm->execute($params)) {
        $result = $stm->fetch(\PDO::FETCH_ASSOC);
      }
      return $result;
    } catch (Exception $e) {
      $this->outputError($e->getMessage());
    }
  }
  public function fetchColumn($sql, $params = array()) {
    $result = &#39;&#39;;
    try {
      $stm = $this->dbh->prepare($sql);
      if ($stm && $stm->execute($params)) {
        $result = $stm->fetchColumn();
      }
      return $result;
    } catch (Exception $e) {
      $this->outputError($e->getMessage());
    }
  }
  public function insert($table, $params = array(), $returnLastId = true) {
    $_implode_field = &#39;&#39;;
    $fields = array_keys($params);
    $_implode_field = implode(&#39;,&#39;, $fields);
    $_implode_value = &#39;&#39;;
    foreach ($fields as $value) {
      $_implode_value .= &#39;:&#39;. $value.&#39;,&#39;;
    }
    $_implode_value = trim($_implode_value, &#39;,&#39;);
    $sql = &#39;INSERT INTO &#39; . $table . &#39;(&#39; . $_implode_field . &#39;) VALUES (&#39;.$_implode_value.&#39;)&#39;;
    try {
      $stm = $this->dbh->prepare($sql);
      $result = $stm->execute($params);
      if ( $returnLastId ) {
        $result = $this->dbh->lastInsertId();
      }
      return $result;
    } catch (Exception $e) {
      $this->outputError($e->getMessage());
    }
  }
  public function update($table, $params = array(), $where = null) {
    $_implode_field = &#39;&#39;;
    $_implode_field_arr = array();
    if ( empty($where) ) {
      return false;
    }
    $fields = array_keys($params);
    foreach ($fields as $key) {
      $_implode_field_arr[] = $key . &#39;=&#39; . &#39;:&#39;.$key;
    }
    $_implode_field = implode(&#39;,&#39;, $_implode_field_arr);
    $sql = &#39;UPDATE &#39; . $table . &#39; SET &#39; . $_implode_field . &#39; WHERE &#39; . $where;
    try {
      $stm = $this->dbh->prepare($sql);
      $result = $stm->execute($params);
      return $result;
    } catch (Exception $e) {
      $this->outputError($e->getMessage());
    }
  }
  public function delete($sql, $params = array()) {
    try {
      $stm = $this->dbh->prepare($sql);
      $result = $stm->execute($params);
      return $result;
    } catch (Exception $e) {
      $this->outputError($e->getMessage());
    }
  }
  public function exec($sql, $params = array()) {
    try {
      $stm = $this->dbh->prepare($sql);
      $result = $stm->execute($params);
      return $result;
    } catch (Exception $e) {
      $this->outputError($e->getMessage());
    }
  }
  private function outputError($strErrMsg) {
    throw new Exception("MySQL Error: " . $strErrMsg);
  }
  public function __destruct() {
    $this->dbh = null;
  }
}

Example:

<?php
require_once &#39;./db.class.php&#39;;
$pdo = db::getInstance(&#39;127.0.0.1&#39;, &#39;root&#39;, &#39;111111&#39;, &#39;php_cms&#39;);
$sql = "select id, title1 from cms_wz where id = :id limit 1";
$parame = array(&#39;id&#39; => 12,);
$res = $pdo->fetchOne($sql, $parame);
var_dump($res);
$sql = &#39;SELECT * FROM cms_link&#39;;
$result = $db->fetchAll($sql);
print_r($result);
//查询记录数量
$sql = &#39;SELECT COUNT(*) FROM cms_link&#39;;
$count = $db->fetchColumn($sql);
echo $count;
$data = array(
  &#39;siteid&#39; => 1,
  &#39;linktype&#39; => 1,
  &#39;name&#39; => &#39;google&#39;,
  &#39;url&#39; => &#39;http://www.google.com&#39;,
  &#39;listorder&#39; => 0,
  &#39;elite&#39; => 0,
  &#39;passed&#39; => 1,
  &#39;addtime&#39; => time()
  );
$lastInsertId = $db->insert(&#39;cms_link&#39;, $data);
echo $lastInsertId;
//用 try
 try {
     $result = $pdo->insert(&#39;news&#39;, $essay);
   } catch (Exception $e) {
     error_log($e->getMessage());
     error_log($e->getMessage() . &#39; in &#39; . __FILE__ . &#39; on line &#39; . __LINE__);
     saveLog(&#39;url文章 : &#39; . $essay[&#39;link&#39;] . &#39;  数据插入失败<br>&#39;);
     continue;
   }
$data = array(
  &#39;siteid&#39; => 1,
  &#39;linktype&#39; => 1,
  &#39;name&#39; => &#39;google&#39;,
  &#39;url&#39; => &#39;http://www.google.com&#39;,
  &#39;listorder&#39; => 0,
  &#39;elite&#39; => 0,
  &#39;passed&#39; => 1,
  &#39;addtime&#39; => time()
  );
$db->insert(&#39;cms_link&#39;, $data);
$sql = &#39;DELETE FROM cms_link WHERE linkid=4&#39;;
$result = $db->delete($sql);
var_dump($result);

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