PHP PDO (ii)

Definition: PDO (php Data Object) is an extension supported by PHP5, which defines a lightweight, consistent interface for PHP access to a variety of databases.

PDO is a significant feature in PHP5, and PHP6 will only use PDO to process the database by default. And we'll use PDO to unify the operations of querying and retrieving data from various databases.

PHP pdo->query () querying data records and returning query resultspdo->query ()

Pdo->query () is used to query data records and return query results.

Grammar:

pdo->query () 
Pdo->query () is used to query data records and return query results.
 
Grammar:
 
 
Example:
 
<?php//construct PDO connection $DBH = "Mysql:host=localhost;dbname=test"; $db = new PDO ($dbh, ' root ', ' root123 '); $db->query ("Set character set ' GBK '");  Query Data $sql = "SELECT * from user"; $sth = $db->query ($sql); while ($row = $sth->fetch ()) {     echo "user name:". $row [' username ']. " <br/> ";     echo "Email:". $row [' email ']. " <br/> ";     
 
In the example above, we modeled the MySQL Tutorial section of the query example, using the PDO approach to the User table query operation.
 Pdostatement->fetch () 
The fetch () method in PDO is used to get a row of results from the result set, which behaves like mysql_fetch_array (), unlike the method, which not only returns an array but also returns an object.
 
Grammar:
 
 
Mode is an optional parameter that represents the type of result set you want to return, which defaults to the array form common to associative and numeric indexes.
 
  
 

   
  

    The mode parameter has the following values: 
  
   
  
 
   
 
    
Take value
 
    
Description
 
   
 
   
 
    
Pdo::fetch_assoc
 
    
Associative index (field name) array form
 
   
 
   
 
    
Pdo::fetch_num
 
    
Numeric indexed Array Form
 
   
 
   
 
    
Pdo::fetch_both
 
    
By default, both associative and numeric indexed array forms have
 
   
 
   
 
    
Pdo::fetch_obj
 
    
In the form of an object
 
   
 
   
 
    
Pdo::fetch_bound
 
    
Assigning the value of a column to a variable by using the Bindcolumn () method
 
   
 
   
 
    
Pdo::fetch_class
 
    
Returns a result set in the form of a class that is automatically created if the specified class property does not exist
 
   
 
   
 
    
Pdo::fetch_into
 
    
Merge data into an existing class to return
 
   
 
   
 
    
Pdo::fetch_lazy
 
    
Combines Pdo::fetch_both and pdo::fetch_obj to create object variables when they are invoked
 
   
 
  
  
 
 
Pdostatement->setfetchmode ()
If you do not specify a result type that is returned in fetch (), you can also use the Setfetchmode () method setting separately, such as:
 
... $sth = $db->query ($sql); $sth->setfetchmode (PDO::FETCH_ASSOC); while ($row = $result->fetch ()) {     
 Pdostatement->fetchall ()
 
The Fetchall () method is used to remove data from the dataset once and into the array.
 
Grammar:
 
 
Mode is an optional parameter that represents the array that you want to return, Column_index represents the column index number, which is specified when mode takes the value pdo::fetch_column.
 
  
 

   
  

    The mode parameter has the following values: 
  
   
  
 
   
 
    
Take value
 
    
Description
 
   
 
   
 
    
Pdo::fetch_column
 
    
Specifies that a column in the returned result set is returned, with the specific column index specified by the Column_index parameter
 
   
 
   
 
    
Pdo::fetch_unique
 
    
Returns the result set as the first key value in the table below, followed by the following table
 
   
 
   
 
    
Pdo::fetch_group
 
    
Group by the value of the specified column
 
   
 
  
  
 
 
Example:
 
$sth = $db->query ($sql); $row = $sth->fetchall ();  Returns only username (index=1) $row = $sth->fetchall (pdo::fetch_column, 1);  
 
Pdo->query (String statement)

Example:

<?php//construct PDO connection $DBH = \ "Mysql:host=localhost;dbname=test\"; $db = new PDO ($DBH, \ ' root\ ', \ ' root123\ '); $db->query (\ "set character set \ ' Gbk\ ' \");  Query data $sql = \ "SELECT * from User\"; $sth = $db->query ($sql); while ($row = $sth->fetch ()) {     echo \ "user name: \". $row \[\ ' username\ ' \].\ "<br/>\";     echo \ "e-mail: \". $row \[\ ' email\ ' \].\ "<br/>\";     

In the example above, we modeled the MySQL Tutorial section of the query example, using the PDO approach to the User table query operation.

Pdostatement->fetch ()

The fetch () method in PDO is used to get a row of results from the result set, which behaves like mysql_fetch_array (), unlike the method, which not only returns an array but also returns an object.

Grammar:

Mode is an optional parameter that represents the type of result set you want to return, which defaults to the array form common to associative and numeric indexes.

The mode parameter has the following values:

Take value	Description
Pdo::fetch_assoc	Associative index (field name) array form
Pdo::fetch_num	Numeric indexed Array Form
Pdo::fetch_both	By default, both associative and numeric indexed array forms have
Pdo::fetch_obj	In the form of an object
Pdo::fetch_bound	Assigning the value of a column to a variable by using the Bindcolumn () method
Pdo::fetch_class	Returns a result set in the form of a class that is automatically created if the specified class property does not exist
Pdo::fetch_into	Merge data into an existing class to return
Pdo::fetch_lazy	Combines Pdo::fetch_both and pdo::fetch_obj to create object variables when they are invoked

Pdostatement->setfetchmode ()

If you do not specify a result type that is returned in fetch (), you can also use the Setfetchmode () method setting separately, such as:

... $sth = $db->query ($sql); $sth->setfetchmode (PDO::FETCH_ASSOC); while ($row = $result->fetch ()) {     

Pdostatement->fetchall ()

The Fetchall () method is used to remove data from the dataset once and into the array.

Grammar:

Mode is an optional parameter that represents the array that you want to return, Column_index represents the column index number, which is specified when mode takes the value pdo::fetch_column.

The mode parameter has the following values:

Take value	Description
Pdo::fetch_column	Specifies that a column in the returned result set is returned, with the specific column index specified by the Column_index parameter
Pdo::fetch_unique	Returns the result set as the first key value in the table below, followed by the following table
Pdo::fetch_group	Group by the value of the specified column

Example:

$sth = $db->query ($sql); $row = $sth->fetchall ();  Returns only username (index=1) $row = $sth->fetchall (pdo::fetch_column, 1);