php 连接mysql（查询 增删改）

Posted 2020-09-15 zjone391

1、连接数据库方法：

<?php
//方法1
$mysqli = new mysqli("localhost", "root", "root", "easyadmin");
if (!$mysqli) {
    echo "database error";
} else {
    echo "php env successful";
}
$mysqli->close();

//方法2
try {
    $dbh = new PDO(\'mysql:host=localhost;dbname=easyadmin\', \'root\', \'root\', array(PDO::ATTR_PERSISTENT => true)); //持久性连接
    $dbh->setAttribute(PDO::ATTR_ERRMODE, PDO::ERRMODE_EXCEPTION);
    $dbh->exec(\'SET CHARACTER SET utf8\');
    echo "连接成功";
    echo "<br/>";
    /* 1.断开连接*/
    //$dbh = null;
    $name = \'kevin2%\';
    /* 2.查询：sql语句中user与name不能是单引号‘’,是左上角的波浪线~,sql语句以外的可以是单引号，否则查询语句会报错*/
    $sql = "select * from `user` where `name` like :name";
    $stmt = $dbh->prepare($sql);
    $stmt->execute(array(\':name\' => $name));
    while ($row = $stmt->fetch(PDO::FETCH_ASSOC)) {
        print_r($row);
        echo("<br/>");
    }
//    /*3.添加*/
//    $sql = "INSERT INTO `user` (`name` ,`password`)VALUES (:name, :password)";
//    $stmt = $dbh->prepare($sql);
//    $stmt->execute(array(\':name\' => \'kevin2\', \':password\' => \'123459\'));
//    echo $dbh->lastInsertId();

    /*4.删除*/
    $name = "zj";
    $sql = "delete from `user` where `name` like :name";
    $stmt = $dbh->prepare($sql);
    $stmt->execute(array(\':name\' => $name));
    echo $stmt->rowCount();

    /*5.修改*/
    $id = 3;
    $sql = "update `user` set `password`=:password where `id`=:id ";
    $stmt = $dbh->prepare($sql);
    $stmt->execute(array(\':id\' => $id, \':password\' => \'testabc\'));
    echo "Update：" . $stmt->rowCount();


} catch (PDOException $ex) {
    print"Error!:" . $ex->getMessage() . "<br/>";
    die();
}


?>

2.参数绑定
举例：
 $stmt = $dbh->prepare($sql);    
 $stmt->bindParam(\':country\', $country, PDO::PARAM_STR);    
 $stmt->execute();   

 

3.事务

  try {  
  　　$dbh = new PDO(\'mysql:host=localhost;dbname=test\', \'root\', \'root\');  
  　　$dbh->query(\'set names utf8;\');  
  　　$dbh->setAttribute(PDO::ATTR_ERRMODE, PDO::ERRMODE_EXCEPTION);  
  　　$dbh->beginTransaction();  
  　　$dbh->exec("Insert INTO `test`.`table` (`name` ,`age`)VALUES (\'mick\', 22);");  
 　　 $dbh->exec("Insert INTO `test`.`table` (`name` ,`age`)VALUES (\'lily\', 29);"); 
 　　 $dbh->exec("Insert INTO `test`.`table` (`name` ,`age`)VALUES (\'susan\', 21);");  
 　　 $dbh->commit(); 
 } catch (Exception $e) {  
 　　 $dbh->rollBack();  
 　　 echo "Failed: " . $e->getMessage();  
 } 

 

4.foreach语句

<?php
$dbh->query($sql); 当$sql 中变量可以用$dbh->quote($params); //转义字符串的数据
$sql = \'Select * from city where CountryCode =\'.$dbh->quote($country);  //引用
foreach ($dbh->query($sql) as $row)   {    
 print $row[\'Name\'] . "/t";    
 print $row[\'CountryCode\'] . "/t";    
 print $row[\'Population\'] . "/n"; 
} 
?>