274 lines
9.5 KiB
PHP
274 lines
9.5 KiB
PHP
<?php
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/**
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* 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
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* with the matching entry in the $cfg global variable.
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*
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* --> First create an object of dblayer --> $db = new DBLayer('short database name used in config')
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*
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* --> Insert --> $db->insert( $tb_name, $data )
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* $tb_name = table name in which we want to insert data
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* $data = array of data that needs to be inserted in format('fieldname' => $value) where fieldname must be a field in that table.
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*
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* --> select --> $db->select( $tb_name, $data, $where )
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* $tb_name = table name which we want to select
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* $data = array of data which is then required in WHERE clause in format array('fieldname'=>$value) fieldname must be a field in that table.
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* $where = string in format ('fieldname=:fieldname') where :fieldname takes it's value from $data array.
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*
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* --> update --> $db->update( $tb_name, $data, $where )
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* $tb_name = table name which we want to update
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* $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.
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* $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.
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*
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* --> delete --> $db->delete( $tb_name, $data, $where )
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* $tb_name = table name where we want to delete.
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* $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.
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* $where = string in format ('fieldname=:fieldname') where :fieldname takes it's value from $data array.
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*
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*
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* @author Daan Janssens, mentored by Matthew Lagoe
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*
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*/
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$PDOCache = array();
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class DBLayer {
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private $PDO;
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private $host;
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private $dbname;
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/**
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* The PDO object, instantiated by the constructor
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*/
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/**
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* The constructor.
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* Instantiates the PDO object attribute by connecting to the arguments matching database(the db info is stored in the $cfg global var)
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*
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* @param $db String, the name of the databases entry in the $cfg global var.
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* @param $dbn String, the name of the databases entry in the $cfg global var if $db referenced to an action(install etc).
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*/
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function __construct($db, $dbn = null)
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{
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global $cfg;
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$this->host = $cfg['db'][$db]['host'];
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$this->dbname = $cfg['db'][$db]['name'];
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global $PDOCache;
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if (isset($PDOCache[$this->host])) {
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$this->PDO = $PDOCache[$this->host]['pdo'];
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} else {
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$dsn = "mysql:";
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$dsn .= "host=" . $cfg['db'][$db]['host'] . ";";
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// $dsn .= "dbname=" . $cfg['db'][$db]['name'] . ";";
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$dsn .= "port=" . $cfg['db'][$db]['port'] . ";";
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$opt = array(
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PDO::ATTR_ERRMODE => PDO::ERRMODE_EXCEPTION,
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PDO::ATTR_DEFAULT_FETCH_MODE => PDO::FETCH_ASSOC,
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PDO::ATTR_PERSISTENT => true
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);
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$this->PDO = new PDO($dsn, $cfg['db'][$db]['user'], $cfg['db'][$db]['pass'], $opt);
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$PDOCache[$this->host] = array();
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$PDOCache[$this->host]['pdo'] = $this->PDO;
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$PDOCache[$this->host]['use'] = $this->dbname;
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$this->PDO->query('USE ' . $this->dbname . ';'); // FIXME safety
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}
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}
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function __destruct() {
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$this->PDO = NULL;
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}
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function useDb() {
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global $PDOCache;
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if ($PDOCache[$this->host]['use'] != $this->dbname) {
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$PDOCache[$this->host]['use'] = $this->dbname;
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$this->PDO->query('USE ' . $this->dbname . ';'); // FIXME safety
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}
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}
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/**
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* Execute a query that doesn't have any parameters.
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*
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* @param $query the mysql query.
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* @return returns a PDOStatement object.
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*/
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public function executeWithoutParams($query) {
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$this->useDb();
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$statement = $this->PDO->prepare($query);
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$statement->execute();
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return $statement;
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}
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/**
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* Execute a query that has parameters.
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*
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* @param $query the mysql query.
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* @param $params the parameters that are being used by the query.
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* @return returns a PDOStatement object.
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*/
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public function execute( $query, $params ) {
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$this->useDb();
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$statement = $this -> PDO -> prepare( $query );
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$statement -> execute( $params );
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return $statement;
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}
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/**
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* Insert function which returns id of the inserting field.
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*
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* @param $tb_name table name where we want to insert data.
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* @param $data the parameters that are being inserted into table.
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* @return returns the id of the last inserted element.
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*/
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public function executeReturnId( $tb_name, $data, $datafunc = array() ) {
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$this->useDb();
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$field_options = implode(',', array_merge(array_keys($data), array_keys($datafunc)));
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$field_values = implode(',', array_merge(array(':' . implode(',:', array_keys($data))), array_values($datafunc)));
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try {
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$sth = $this -> PDO -> prepare( "INSERT INTO $tb_name ($field_options) VALUE ($field_values)" );
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foreach ( $data as $key => $value )
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{
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$sth -> bindValue( ":$key", $value );
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}
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$this -> PDO -> beginTransaction();
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$sth -> execute();
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$lastId = $this -> PDO -> lastInsertId();
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$this -> PDO -> commit();
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}
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catch ( Exception $e ) {
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// for rolling back the changes during transaction
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// $this -> PDO -> rollBack();
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throw $e; // new Exception( "error in inseting" );
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}
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return $lastId;
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}
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/**
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* Select function using prepared statement.
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* For selecting particular fields.
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*
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* @param string $param field to select, can be multiple fields.
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* @param string $tb_name Table Name to Select.
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* @param array $data array of data to be used in WHERE clause in format('fieldname'=>$value). 'fieldname' must be a field in that table.
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* @param string $where where to select.
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* @return statement object.
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*/
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public function selectWithParameter( $param, $tb_name, $data, $where ) {
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$this->useDb();
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try {
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$sth = $this->PDO->prepare( "SELECT $param FROM $tb_name WHERE $where" );
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$sth->execute( $data );
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}
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catch ( Exception $e ) {
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throw $e; // new Exception( "error selection" );
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return false;
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}
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return $sth;
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}
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/**
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* Select function using prepared statement.
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* For selecting all fields in a table.
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*
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* @param string $tb_name Table Name to Select.
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* @param array $data array of data to be used with WHERE part in format('fieldname'=>$value,...). 'fieldname' must be a field in that table.
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* @param string $where where to select in format('fieldname=:fieldname' AND ...).
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* @return statement object.
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*/
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public function select($tb_name, $data , $where) {
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$this->useDb();
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try {
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$sth = $this->PDO->prepare("SELECT * FROM $tb_name WHERE $where");
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$sth->execute( $data );
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}
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catch (Exception $e) {
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throw $e; // new Exception( "error selection" );
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return false;
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}
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return $sth;
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}
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/**
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* Update function with prepared statement.
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*
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* @param string $tb_name name of the table on which operation to be performed.
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* @param array $data array of data in format('fieldname' => $value,...).Here, only those fields must be stored which needs to be updated.
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* @param string $where where part in format ('fieldname'= $value AND ...). 'fieldname' must be a field in that table.
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* @throws Exception error in updating.
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*/
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public function update( $tb_name, $data, $where ) {
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$this->useDb();
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$field_option_values = null;
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foreach ( $data as $key => $value ) {
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$field_option_values .= ",$key" . '=:' . $key;
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}
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$field_option_values = ltrim( $field_option_values, ',' );
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try {
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$sth = $this -> PDO -> prepare( "UPDATE $tb_name SET $field_option_values WHERE $where " );
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foreach ( $data as $key => $value ) {
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$sth -> bindValue( ":$key", $value );
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}
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$this -> PDO -> beginTransaction();
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$sth -> execute();
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$this -> PDO -> commit();
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}
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catch ( Exception $e ) {
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$this->PDO->rollBack();
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throw $e; // new Exception( 'error in updating' );
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return false;
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}
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return true;
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}
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/**
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* insert function using prepared statements.
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*
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* @param string $tb_name Name of the table on which operation to be performed.
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* @param array $data array of data to insert in format('fieldname' => $value,....). 'fieldname' must be a field in that table.
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* @throws error in inserting.
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*/
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public function insert($tb_name, $data, $datafunc = array()) {
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$this->useDb();
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$field_options = implode(',', array_merge(array_keys($data), array_keys($datafunc)));
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$field_values = implode(',', array_merge(array(':' . implode(',:', array_keys($data))), array_values($datafunc)));
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try {
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$sth = $this->PDO->prepare("INSERT INTO $tb_name ($field_options) VALUE ($field_values)");
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foreach ($data as $key => $value) {
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$sth->bindValue(":$key", $value);
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}
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$this->PDO->beginTransaction();
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// execution
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$sth->execute();
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$this->PDO->commit();
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}
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catch (Exception $e) {
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// for rolling back the changes during transaction
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$this->PDO->rollBack();
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throw $e; // new Exception("error in inserting");
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}
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}
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/**
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* Delete database entery using prepared statement.
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*
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* @param string $tb_name table name on which operations to be performed.
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* @param $data array with values in the format('fieldname'=> $value,...). 'fieldname' must be a field in that table.
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* @param string $where condition based on $data array in the format('fieldname=:fieldname' AND ...).
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* @throws error in deleting.
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*/
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public function delete( $tb_name, $data, $where ) {
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$this->useDb();
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try {
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$sth = $this->PDO->prepare( "DELETE FROM $tb_name WHERE $where" );
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$this->PDO->beginTransaction();
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$sth->execute( $data );
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$this->PDO->commit();
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}
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catch (Exception $e) {
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$this->PDO->rollBack();
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throw $e; // new Exception( "error in deleting" );
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}
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}
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}
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