php mysql PDO use, phpmysqlpdo use_PHP tutorial-PHP Tutorial-php.cn

php mysql PDO is used, phpmysqlpdo is used

<span> 1</span> <?<span>php
</span><span> 2</span> <span>$dbh</span> = <span>new</span> PDO('mysql:host=localhost;dbname=access_control', 'root', ''<span>);  
</span><span> 3</span> <span>$dbh</span>->setAttribute(PDO::ATTR_ERRMODE, PDO::<span>ERRMODE_EXCEPTION);  
</span><span> 4</span> <span>$dbh</span>-><span>exec</span>('set names utf8'<span>); 
</span><span> 5</span> <span>/*</span><span>添加</span><span>*/</span>
<span> 6</span> <span>//</span><span>$sql = "INSERT INTO `user` SET `login`=:login AND `password`=:password"; </span>
<span> 7</span> <span>$sql</span> = "INSERT INTO `user` (`login` ,`password`)VALUES (:login, :password)";  <span>$stmt</span> = <span>$dbh</span>->prepare(<span>$sql</span>);  <span>$stmt</span>->execute(<span>array</span>(':login'=>'kevin2',':password'=>''<span>));  
</span><span> 8</span> <span>echo</span> <span>$dbh</span>-><span>lastinsertid();  
</span><span> 9</span> <span>/*</span><span>修改</span><span>*/</span>
<span>10</span> <span>$sql</span> = "UPDATE `user` SET `password`=:password WHERE `user_id`=:userId"<span>;  
</span><span>11</span> <span>$stmt</span> = <span>$dbh</span>->prepare(<span>$sql</span><span>);  
</span><span>12</span> <span>$stmt</span>->execute(<span>array</span>(':userId'=>'7', ':password'=>'4607e782c4d86fd5364d7e4508bb10d9'<span>));  
</span><span>13</span> <span>echo</span> <span>$stmt</span>-><span>rowCount(); 
</span><span>14</span> <span>/*</span><span>删除</span><span>*/</span>
<span>15</span> <span>$sql</span> = "DELETE FROM `user` WHERE `login` LIKE 'kevin_'"; <span>//</span><span>kevin%  </span>
<span>16</span> <span>$stmt</span> = <span>$dbh</span>->prepare(<span>$sql</span><span>);  
</span><span>17</span> <span>$stmt</span>-><span>execute();  
</span><span>18</span> <span>echo</span> <span>$stmt</span>-><span>rowCount();  
</span><span>19</span> <span>/*</span><span>查询</span><span>*/</span>
<span>20</span> <span>$login</span> = 'kevin%'<span>;  
</span><span>21</span> <span>$sql</span> = "SELECT * FROM `user` WHERE `login` LIKE :login"<span>;  
</span><span>22</span> <span>$stmt</span> = <span>$dbh</span>->prepare(<span>$sql</span><span>);  
</span><span>23</span> <span>$stmt</span>->execute(<span>array</span>(':login'=><span>$login</span><span>));  
</span><span>24</span> <span>while</span>(<span>$row</span> = <span>$stmt</span>->fetch(PDO::<span>FETCH_ASSOC)){     
</span><span>25</span>  <span>print_r</span>(<span>$row</span><span>);  
</span><span>26</span> <span>}  
</span><span>27</span> <span>print_r</span>( <span>$stmt</span>->fetchAll(PDO::<span>FETCH_ASSOC)); 
</span><span>28</span> ?>

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1 Establish connection

<span>1</span> <?<span>php
</span><span>2</span> <span>$dbh</span>=newPDO('mysql:host=localhost;port=3306; dbname=test',<span>$user</span>,<span>$pass</span>,<span>array</span><span>(
</span><span>3</span> PDO::ATTR_PERSISTENT=><span>true</span>
<span>4</span> <span>));
</span><span>5</span> ?>

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Persistence link PDO::ATTR_PERSISTENT=>true

2. Catching errors

<span> 1</span> <?<span>php
</span><span> 2</span> <span>try</span><span>{
</span><span> 3</span> <span>$dbh</span>=newPDO('mysql:host=localhost;dbname=test',<span>$user</span>,<span>$pass</span><span>);
</span><span> 4</span> 
<span> 5</span> <span>$dbh</span>->setAttribute(PDO::ATTR_ERRMODE,PDO::<span>ERRMODE_EXCEPTION);
</span><span> 6</span> 
<span> 7</span> <span>$dbh</span>-><span>exec</span>("SET CHARACTER SET utf8"<span>);
</span><span> 8</span> <span>$dbh</span>=<span>null</span>; <span>//</span><span>断开连接</span>
<span> 9</span> }<span>catch</span>(PDOException<span>$e</span><span>){
</span><span>10</span> <span>print</span>"Error!:".<span>$e</span>->getMessage()."<br/>"<span>;
</span><span>11</span> <span>die</span><span>();
</span><span>12</span> <span>}
</span><span>13</span> ?>

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3. Business

<span> 1</span> <?<span>php
</span><span> 2</span> <span>try</span><span>{
</span><span> 3</span> <span>$dbh</span>->setAttribute(PDO::ATTR_ERRMODE,PDO::<span>ERRMODE_EXCEPTION);
</span><span> 4</span> 
<span> 5</span> <span>$dbh</span>->beginTransaction();<span>//</span><span>开启事务</span>
<span> 6</span> <span>$dbh</span>-><span>exec</span>("insertintostaff(id,first,last)values(23,'Joe','Bloggs')"<span>);
</span><span> 7</span> <span>$dbh</span>-><span>exec</span>("<span>insertintosalarychange(id,amount,changedate)
</span><span> 8</span> values(23,50000,NOW())"<span>);
</span><span> 9</span> <span>$dbh</span>->commit();<span>//</span><span>提交事务</span>
<span>10</span> 
<span>11</span> }<span>catch</span>(<span>Exception</span><span>$e</span><span>){
</span><span>12</span> <span>$dbh</span>->rollBack();<span>//</span><span>错误回滚</span>
<span>13</span> <span>echo</span>"Failed:".<span>$e</span>-><span>getMessage();
</span><span>14</span> <span>}
</span><span>15</span> ?>

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4. Error handling

a. Silent mode (default mode)

$dbh->setAttribute(PDO::ATTR_ERRMODE,PDO::ERRMODE_SILENT); //Do not display errors

$dbh->setAttribute(PDO::ATTR_ERRMODE, PDO::ERRMODE_WARNING);//Display warning errors and continue execution

$dbh->setAttribute(PDO::ATTR_ERRMODE,PDO::ERRMODE_EXCEPTION);//A fatal error occurs, PDOException

<span> 1</span> <?<span>php
</span><span> 2</span> <span>try</span><span>{    
</span><span> 3</span>  <span>$dbh</span> = <span>new</span> PDO(<span>$dsn</span>, <span>$user</span>, <span>$password</span><span>);    
</span><span> 4</span>  <span>$sql</span> = 'Select * from city where CountryCode =:country'<span>;    
</span><span> 5</span>  <span>$dbh</span>->setAttribute(PDO::ATTR_ERRMODE, PDO::<span>ERRMODE_WARNING);    
</span><span> 6</span>  <span>$stmt</span> = <span>$dbh</span>->prepare(<span>$sql</span><span>);    
</span><span> 7</span>  <span>$stmt</span>->bindParam(':country', <span>$country</span>, PDO::<span>PARAM_STR);    
</span><span> 8</span>  <span>$stmt</span>-><span>execute();    
</span><span> 9</span>  <span>while</span> (<span>$row</span> = <span>$stmt</span>->fetch(PDO::<span>FETCH_ASSOC)) {      
</span><span>10</span>   <span>print</span> <span>$row</span>['Name'] . "/t"<span>;    
</span><span>11</span> <span> }  
</span><span>12</span> }   <span>//</span><span> if there is a problem we can handle it here  </span>
<span>13</span> <span>catch</span> (PDOException <span>$e</span><span>)  {    
</span><span>14</span>  <span>echo</span> 'PDO Exception Caught.  '<span>;    
</span><span>15</span>  <span>echo</span> 'Error with the database: <br />'<span>;    
</span><span>16</span>  <span>echo</span> 'SQL Query: ', <span>$sql</span><span>;   
</span><span>17</span>  <span>echo</span> 'Error: ' . <span>$e</span>-><span>getMessage();  
</span><span>18</span> <span>} 
</span><span>19</span> ?>

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1. Use query()

<?<span>php
</span><span>$dbh</span>->query(<span>$sql</span>); 当<span>$sql</span> 中变量可以用<span>$dbh</span>->quote(<span>$params</span>); <span>//</span><span>转义字符串的数据</span>

<span>$sql</span> = 'Select * from city where CountryCode ='.<span>$dbh</span>->quote(<span>$country</span><span>);  
</span><span>foreach</span> (<span>$dbh</span>->query(<span>$sql</span>) <span>as</span> <span>$row</span><span>)   {    
 </span><span>print</span> <span>$row</span>['Name'] . "/t"<span>;    
 </span><span>print</span> <span>$row</span>['CountryCode'] . "/t"<span>;    
 </span><span>print</span> <span>$row</span>['Population'] . "/n"<span>; 
} 
</span>?>

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2. Use prepare, bindParam and execute [recommended, you can also add, modify, delete]

<?<span>php
</span><span>$dbh</span>->prepare(<span>$sql</span><span>); 产生了个PDOStatement对象

PDOStatement</span>-><span>bindParam()

PDOStatement</span>->execute();<span>//</span><span>可以在这里放绑定的相应变量</span>
?>

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3. Things

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

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Commonly used methods of PDO:
PDO::query() is mainly used for operations (PDOStatement) with recorded results returned, especially select operations.

PDO::exec() is mainly for operations that do not return a result set. Such as insert, update and other operations. Returns the number of affected rows.
PDO::lastInsertId() returns the last ID of the last insertion operation, but please note: if you insert into tb(col1,col2) values(v1,v2),(v11,v22).. For multiple records, lastinsertid() returns only the ID when the first record (v1, v2) was inserted, not the record ID of the last record inserted.
PDOStatement::fetch() is used to obtain a record. Use while to traverse.
PDOStatement::fetchAll() fetches all records into one.
PDOStatement::fetchcolumn([int column_indexnum]) is used to directly access the column. The parameter column_indexnum is the index value of the column in the row starting from 0. However, this method can only obtain one column of the same row at a time and only needs to be executed once. , jump to the next line. Therefore, it is easier to use when directly accessing a certain column, but it is not useful when traversing multiple columns.
PDOStatement::rowcount() is suitable for obtaining the number of records when using the query("select...") method. It can also be used in preprocessing. $stmt->rowcount();
PDOStatement::columncount() is suitable for obtaining the number of columns in a record when using the query("select...") method.

Notes:
1. Choose fetch or fetchall?
When the record set is small, using fetchall is more efficient and reduces the number of retrieval times from the database. However, for large result sets, using fetchall will bring a lot of burden to the system. The amount of data the database needs to transmit to the WEB front-end is too large and inefficient.
2. fetch() or fetchall() has several parameters:
mixed pdostatement::fetch([int fetch_style [,int cursor_orientation [,int cursor_offset]]])
array pdostatement::fetchAll( int fetch_style)

fetch_style parameters:
■$row=$rs->fetchAll(PDO::FETCH_BOTH); FETCH_BOTH is the default, can be omitted, and returns the association and index.
■$row=$rs->fetchAll(PDO::FETCH_ASSOC); The FETCH_ASSOC parameter determines that only associative arrays are returned.
■$row=$rs->fetchAll(PDO::FETCH_NUM); Returns the index array
■$row=$rs->fetchAll(PDO::FETCH_OBJ); If fetch() returns the object , if it is fetchall(), returns a two-dimensional array composed of objects