@ -3,13 +3,36 @@
* Handles the database connections. It uses PDO to connect to the different databases. It will use the argument of the constructor to setup a connection to the database
* with the matching entry in the $cfg global variable.
*
* --> First create an object of dblayer --> $db = new DBLayer('short database name used in config')
*
* --> Insert --> $db->insert( $tb_name, $data )
* $tb_name = table name in which we want to insert data
* $data = array of data that needs to be inserted in format('fieldname' => $value) where fieldname must be a field in that table.
*
* --> select --> $db->select( $tb_name, $data, $where )
* $tb_name = table name which we want to select
* $data = array of data which is then required in WHERE clause in format array('fieldname'=>$value) fieldname must be a field in that table.
* $where = string in format ('fieldname=:fieldname') where :fieldname takes it's value from $data array.
*
* --> update --> $db->update( $tb_name, $data, $where )
* $tb_name = table name which we want to update
* $data = array of data which contains the filelds that need to be updated with their values in the format('fieldname' => $value,...) where fieldname must be a field in that table.
* $where = string contains the filename with a value at that field in the format ('fieldname = $value') where fieldname must be a field in that table and $value is value respect to that field.
*
* --> delete --> $db->delete( $tb_name, $data, $where )
* $tb_name = table name where we want to delete.
* $data = array of data which is then required in WHERE clause in format array('fieldname'=> $value) where fieldname must be a field in that table.
* $where = string in format ('fieldname=:fieldname') where :fieldname takes it's value from $data array.
*
*
* @author Daan Janssens, mentored by Matthew Lagoe
*
*/
class DBLayer {
private $PDO;
/**
* *< The PDO object , instantiated by the constructor
* The PDO object, instantiated by the constructor
*/
/**
@ -17,6 +40,7 @@ class DBLayer {
* Instantiates the PDO object attribute by connecting to the arguments matching database(the db info is stored in the $cfg global var)
*
* @param $db String, the name of the databases entry in the $cfg global var.
* @param $dbn String, the name of the databases entry in the $cfg global var if $db referenced to an action(install etc).
*/
function __construct( $db, $dbn = null )
{
@ -49,10 +73,10 @@ class DBLayer {
}
/**
* e xecute a query that doesn't have any parameters
* E xecute a query that doesn't have any parameters.
*
* @param $query the mysql query
* @return returns a PDOStatement object
* @param $query the mysql query.
* @return returns a PDOStatement object.
*/
public function executeWithoutParams( $query ) {
$statement = $this -> PDO -> prepare( $query );
@ -61,11 +85,11 @@ class DBLayer {
}
/**
* execute a query that has parameters
* Execute a query that has parameters.
*
* @param $query the mysql query
* @param $params the parameters that are being used by the query
* @return returns a PDOStatement object
* @param $query the mysql query.
* @param $params the parameters that are being used by the query.
* @return returns a PDOStatement object.
*/
public function execute( $query, $params ) {
$statement = $this -> PDO -> prepare( $query );
@ -74,10 +98,10 @@ class DBLayer {
}
/**
* execute a query (an insertion query) that has parameters and return the id of it's insertion
* Insert function which returns id of the inserting field.
*
* @param $query the mysql query
* @param $params the parameters that are being used by the query
* @param $tb_name table name where we want to insert data.
* @param $data the parameters that are being inserted into table.
* @return returns the id of the last inserted element.
*/
public function executeReturnId( $tb_name, $data ) {
@ -104,12 +128,14 @@ class DBLayer {
}
/**
* Select function using prepared statement
* Select function using prepared statement.
* For selecting particular fields.
*
* @param string $tb_name Table Name to Select
* @param array $data Associative array
* @param string $where where to select
* @return statement object
* @param string $param field to select, can be multiple fields.
* @param string $tb_name Table Name to Select.
* @param array $data array of data to be used in WHERE clause in format('fieldname'=>$value). 'fieldname' must be a field in that table.
* @param string $where where to select.
* @return statement object.
*/
public function selectWithParameter( $param, $tb_name, $data, $where )
{
@ -129,12 +155,13 @@ class DBLayer {
}
/**
* Select function using prepared statement
* Select function using prepared statement.
* For selecting all fields in a table.
*
* @param string $tb_name Table Name to Select
* @param array $data Associative array
* @param string $where where to select
* @return statement object
* @param string $tb_name Table Name to Select.
* @param array $data array of data to be used with WHERE part in format('fieldname'=>$value,...). 'fieldname' must be a field in that table.
* @param string $where where to select in format('fieldname=:fieldname' AND ...).
* @return statement object.
*/
public function select( $tb_name, $data , $where )
{
@ -154,12 +181,12 @@ class DBLayer {
}
/**
* Update function with prepared statement
* Update function with prepared statement.
*
* @param string $tb_name name of the table
* @param array $data associative array with values
* @param string $where where part
* @throws Exception error in updating
* @param string $tb_name name of the table on which operation to be performed.
* @param array $data array of data in format('fieldname' => $value,...).Here, only those fields must be stored which needs to be updated.
* @param string $where where part in format ('fieldname'= $value AND ...). 'fieldname' must be a field in that table.
* @throws Exception error in updating.
*/
public function update( $tb_name, $data, $where )
{
@ -190,10 +217,11 @@ class DBLayer {
}
/**
* insert function using prepared statements
* insert function using prepared statements.
*
* @param string $tb_name Name of the table to insert in
* @param array $data Associative array of data to insert
* @param string $tb_name Name of the table on which operation to be performed.
* @param array $data array of data to insert in format('fieldname' => $value,....). 'fieldname' must be a field in that table.
* @throws error in inserting.
*/
public function insert( $tb_name, $data )
{
@ -216,16 +244,17 @@ class DBLayer {
{
// for rolling back the changes during transaction
$this -> PDO -> rollBack();
throw new Exception( "error in inseting" );
throw new Exception( "error in inser ting" );
}
}
/**
* Delete database entery using prepared statement
* Delete database entery using prepared statement.
*
* @param string $tb_name
* @param string $where
* @throws error in deleting
* @param string $tb_name table name on which operations to be performed.
* @param $data array with values in the format('fieldname'=> $value,...). 'fieldname' must be a field in that table.
* @param string $where condition based on $data array in the format('fieldname=:fieldname' AND ...).
* @throws error in deleting.
*/
public function delete( $tb_name, $data, $where )
{
kaetemi
10 years ago