PDO简介，花千骨剧情简介_PHP教程
- WBOY原創
- 2016-07-13 09:44:44938瀏覽
PDO简介，花千骨剧情简介
php链接数据库 半年后需要更换mysql为集群模式或者有钱了升级oracl数据库，这时的改动相当大，成本高。如果再之前使用PDO，之后再遇见这样的问题就很轻松。
开启PDO:
打开php.ini文件，将需要打开的dll扩展件前面的“;”去掉。
;extension=php_pdo_firebird.dll
;extension=php_pdo_mysql.dll
;extension=php_pdo_oci.dll
;extension=php_pdo_odbc.dll
测试能否使用
打开php.info（）查看到：
使用语法
<span>$db</span>->setAttribute(PDO::ATTR_CASE, PDO::<span>CASE_UPPER);
</span><span>$rs</span> = <span>$db</span>->query("SELECT * FROM foo"<span>);
</span><span>$rs</span>->setFetchMode(PDO::<span>FETCH_ASSOC);
</span><span>$result_arr</span> = <span>$rs</span>-><span>fetchAll();
</span><span>print_r</span>(<span>$result_arr</span>);
setAttribute():
PDO::CASE_LOWER -- 强制列名是小写
PDO::CASE_NATURAL -- 列名按照原始的方式
PDO::CASE_UPPER -- 强制列名为大写
setFetchMode():
PDO::FETCH_ASSOC -- 关联数组形式
PDO::FETCH_NUM -- 数字索引数组形式
PDO::FETCH_BOTH -- 两者数组形式都有，这是缺省的
PDO::FETCH_OBJ -- 按照对象的形式，类似于以前的 mysql_fetch_object()
异常处理：
<span>try</span><span>{
</span><span>$db</span> = <span>new</span> PDO(<span>$dsn</span>,<span>$user</span>,<span>$passwd</span><span>);
}</span><span>catch</span>(PDOException <span>$e</span><span>){
</span><span>print</span> <span>$e</span>->getMessage(); <span>//</span><span> 返回异常信息</span>
<span>print</span> <span>$e</span>->getCode(); <span>//</span><span> 返回异常代码</span>
<span>print</span> <span>$e</span>->getFile(); <span>//</span><span> 返回发生异常的文件名</span>
<span>print</span> <span>$e</span>->getLine(); <span>//</span><span> 返回发生异常的代码行号</span>
<span>print</span> <span>$e</span>->getTrace(); <span>//</span><span> backtrace() 数组</span>
<span>print</span> <span>$e</span>->getTraceAsString(); <span>//</span><span> 已格成化成字符串的 getTrace() 信息 </span>
<span>}
</span><span>$count</span> = <span>$db</span>-><span>exec</span>("insert into info_u set name,nickname ='hefe',job=1;"<span>);
</span><span>print</span> <span>$db</span>-><span>errorCode();
</span><span>print_r</span>(<span>$db</span>-><span>errorinfo());
</span>--------------------------------------------------
[message:protected] => SQLSTATE[HY000] [1045] Access denied for user 'coffee'@'localhost' (using password: YES)
[string:Exception:private] =>
[code:protected] => 1045
[file:protected] => /alidata/www/webpage/signup.php
[line:protected] => 11
[trace:Exception:private] => Array
(
[0] => Array
(
[file] => /alidata/www/webpage/signup.php
[line] => 11
[function] => __construct
[class] => PDO
[type] => ->
[args] => Array
(
[0] => mysql:host=localhost;dbname=fengchao
[1] => coffee
[2] => coffe
)
)
)
[previous:Exception:private] =>
[errorInfo] =>
42S22
<em id="__mceDel"><span>Array</span><span>
(
[</span>0] =><span> 42S22
[</span>1] => 1054<span>
[</span>2] =><span>
Unknown column </span>'name' in 'field list'<span>
)</span></em>
在new新的链接时，异常处理用PDOException();在执行exection()时异常处理使用errorInfo()和errorCode();
errorCode()返回：
00000 //执行正常
1054 //Unknown column 'X' in 'field list' 字段X未出现在在字段中
1110 // 字段出现两次出现两次
1062 //Duplicate entry 'X' for key 'PRIMARY' 重复主键
......