php连数据库

@1 php连接PDO

1.1 pdo类详解

PDO->beginTransaction()          表明回滚起点 ，一批批执行sql语句，成功的话commit，出错的话rollback，而且把之前成功执行的sql语句干掉；

try{
 $dbh = new PDO('mysql:host=localhost;dbname=test','root','password');   //连接PDO，test为数据库名称，root表示mysql用户名称，password表示数据库连接密码;
 $dbh->query('set names utf8');
 $dbh->setAttribute(PDO::ATTR_ERRMODE, PDO::ERRORMODE_EXCEPTION);         //产生致命错误
 $dbh->beginTransaction();                                                //开启事物
 $dbh->exec("insert into `tablename`(`name`,`age`) values ('cj', '22')");   //插入数据
 $dbh->exec("insert into `tablename`(`name`,`age`) values ('fendor', `24`)");  
 $dbh->exec("insert into tablename(`name`,`age`) values ('wang','25')");
 $dbh->commit();                                                          //批执行sql语句
 }
catch(Exception $e){
$dbh->rollBack();                                                     //抛出异常，错误回滚，之前的sql语句全部不执行
echo "Failed:" . $e->getMessage();
}

PDO->commit();        标明回滚结束点，并执行SQL
PDO->__construct()         建立一个PDO连接数据库的实例
PDO->errorCode()         获取错误代码
PDO->errorInfo()          获取错误的信息
PDO->exec()             处理一条SQL语句，并返回所影响的条目数
PDO->getAttribute()         获取一个“数据库连接对象”的属性
PDO->getAvailableDrivers()         获取有效的PDO驱动名称
PDO->lastInsertId()             获取写入的最后一条数据的主键值
PDO->prepare()                  生成一个“查询对象”

 使用prepare，bindParam,execute(建议用于增删改)
1 $dbh->prepare($sql);       //产生一个PDOStatement对象
PDOStatement->bindParam();
PDOStatement->execute();

PDO->query()                 处理一条sql语句，并返回一个“PDOStatement”

$result = $dbh->query("select * from tablename");  //查询所有数据
foreach($result as $k=>$value)    3 {
  echo $value['username'].$value['password']."</br>";  //遍历所有数据
}

PDO->quote()                    为某个SQL中的字符串添加引号
PDO->rollback()            执行回滚
PDO->setAttribute()        为一个数据库连接对象“设定属性”

1.2 PDOStatement

PDOStatement->bindColumn() — Bind a column to a PHP variable
PDOStatement->bindParam() — Binds a parameter to the specified variable name
PDOStatement->bindValue() — Binds a value to a parameter
PDOStatement->closeCursor() — Closes the cursor, enabling the statement to be executed again.
PDOStatement->columnCount() — Returns the number of columns in the result set
PDOStatement->errorCode() — Fetch the SQLSTATE associated with the last operation on the statement handle
PDOStatement->errorInfo() — Fetch extended error information associated with the last operation on the statement handle
PDOStatement->execute() — Executes a prepared statement
PDOStatement->fetch() — Fetches the next row from a result set
PDOStatement->fetchAll() — Returns an array containing all of the result set rows
PDOStatement->fetchColumn() — Returns a single column from the next row of a result set
PDOStatement->fetchObject() — Fetches the next row and returns it as an object.
PDOStatement->getAttribute() — Retrieve a statement attribute
PDOStatement->getColumnMeta() — Returns metadata for a column in a result set
PDOStatement->nextRowset() — Advances to the next rowset in a multi-rowset statement handle
PDOStatement->rowCount() — Returns the number of rows affected by the last SQL statement
PDOStatement->setAttribute() — Set a statement attribute
PDOStatement->setFetchMode() — Set the default fetch mode for this statement

PDO::query()主要用于有记录结果返回的操作（PDOStatement）,特别是select操作；

PDO::exec()主要针对没有结果集合返回的操作，如insert，update等操作；

PDOStatement::fetch()是用来获取一条记录，配合while来遍历；

PDOStatement::fetchall()是获取所有记录到一个中