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Changing Class From Mysqli To PDO

Discussion in 'Web Design & Development' started by CilVine, Mar 22, 2015.

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  1. CilVine

    CilVine Thread Starter

    Joined:
    Apr 7, 2013
    Messages:
    48
    I was just taking a look at the class written below, and wondered what is the best way to rewrite this to work with PDO, rather than MySQLi?

    Here is the entire code:

    <?php

    class MysqlDB {

    protected $_mysql;
    protected $_where = array();
    protected $_query;
    protected $_paramTypeList;

    public function __construct($host, $username, $password, $db) {
    $this->_mysql = new mysqli($host, $username, $password, $db) or die('There was a problem connecting to the database');
    }

    /**
    *
    * @param string $query Contains a user-provided select query.
    * @param int $numRows The number of rows total to return.
    * @return array Contains the returned rows from the query.
    */
    public function query($query)
    {
    $this->_query = filter_var($query, FILTER_SANITIZE_STRING);

    $stmt = $this->_prepareQuery();
    $stmt->execute();
    $results = $this->_dynamicBindResults($stmt);
    return $results;
    }

    /**
    * A convenient SELECT * function.
    *
    * @param string $tableName The name of the database table to work with.
    * @param int $numRows The number of rows total to return.
    * @return array Contains the returned rows from the select query.
    */
    public function get($tableName, $numRows = NULL)
    {

    $this->_query = "SELECT * FROM $tableName";
    $stmt = $this->_buildQuery($numRows);
    $stmt->execute();

    $results = $this->_dynamicBindResults($stmt);
    return $results;
    }

    /**
    *
    * @param <string $tableName The name of the table.
    * @param array $insertData Data containing information for inserting into the DB.
    * @return boolean Boolean indicating whether the insert query was completed succesfully.
    */
    public function insert($tableName, $insertData)
    {
    $this->_query = "INSERT into $tableName";
    $stmt = $this->_buildQuery(NULL, $insertData);
    $stmt->execute();

    if ($stmt->affected_rows)
    return true;
    }

    /**
    * Update query. Be sure to first call the "where" method.
    *
    * @param string $tableName The name of the database table to work with.
    * @param array $tableData Array of data to update the desired row.
    * @return boolean
    */
    public function update($tableName, $tableData)
    {
    $this->_query = "UPDATE $tableName SET ";

    $stmt = $this->_buildQuery(NULL, $tableData);
    $stmt->execute();

    if ($stmt->affected_rows)
    return true;
    }

    /**
    * Delete query. Call the "where" method first.
    *
    * @param string $tableName The name of the database table to work with.
    * @return boolean Indicates success. 0 or 1.
    */
    public function delete($tableName) {
    $this->_query = "DELETE FROM $tableName";

    $stmt = $this->_buildQuery();
    $stmt->execute();

    if ($stmt->affected_rows)
    return true;
    }

    /**
    * This method allows you to specify a WHERE statement for SQL queries.
    *
    * @param string $whereProp A string for the name of the database field to update
    * @param mixed $whereValue The value for the field.
    */
    public function where($whereProp, $whereValue)
    {
    $this->_where[$whereProp] = $whereValue;
    }

    /**
    * This method is needed for prepared statements. They require
    * the data type of the field to be bound with "i" s", etc.
    * This function takes the input, determines what type it is,
    * and then updates the param_type.
    *
    * @param mixed $item Input to determine the type.
    * @return string The joined parameter types.
    */
    protected function _determineType($item)
    {
    switch (gettype($item)) {
    case 'string':
    return 's';
    break;

    case 'integer':
    return 'i';
    break;

    case 'blob':
    return 'b';
    break;

    case 'double':
    return 'd';
    break;
    }
    }

    /**
    * Abstraction method that will compile the WHERE statement,
    * any passed update data, and the desired rows.
    * It then builds the SQL query.
    *
    * @param int $numRows The number of rows total to return.
    * @param array $tableData Should contain an array of data for updating the database.
    * @return object Returns the $stmt object.
    */
    protected function _buildQuery($numRows = NULL, $tableData = false)
    {
    $hasTableData = null;
    if (gettype($tableData) === 'array') {
    $hasTableData = true;
    }

    // Did the user call the "where" method?
    if (!empty($this->_where)) {
    $keys = array_keys($this->_where);
    $where_prop = $keys[0];
    $where_value = $this->_where[$where_prop];

    // if update data was passed, filter through
    // and create the SQL query, accordingly.
    if ($hasTableData) {
    $i = 1;
    $pos = strpos($this->_query, 'UPDATE');
    if ( $pos !== false) {
    foreach ($tableData as $prop => $value) {
    // determines what data type the item is, for binding purposes.
    $this->_paramTypeList .= $this->_determineType($value);

    // prepares the reset of the SQL query.
    if ($i === count($tableData)) {
    $this->_query .= $prop . " = ? WHERE " . $where_prop . "= " . $where_value;
    } else {
    $this->_query .= $prop . ' = ?, ';
    }

    $i++;
    }
    }
    } else {
    // no table data was passed. Might be SELECT statement.
    $this->_paramTypeList = $this->_determineType($where_value);
    $this->_query .= " WHERE " . $where_prop . "= ?";
    }
    }

    // Determine if is INSERT query
    if ($hasTableData) {
    $pos = strpos($this->_query, 'INSERT');

    if ($pos !== false) {
    //is insert statement
    $keys = array_keys($tableData);
    $values = array_values($tableData);
    $num = count($keys);

    // wrap values in quotes
    foreach ($values as $key => $val) {
    $values[$key] = "'{$val}'";
    $this->_paramTypeList .= $this->_determineType($val);
    }

    $this->_query .= '(' . implode($keys, ', ') . ')';
    $this->_query .= ' VALUES(';
    while ($num !== 0) {
    ($num !== 1) ? $this->_query .= '?, ' : $this->_query .= '?)';
    $num--;
    }
    }
    }

    // Did the user set a limit
    if (isset($numRows)) {
    $this->_query .= " LIMIT " . (int) $numRows;
    }

    // Prepare query
    $stmt = $this->_prepareQuery();

    // Bind parameters
    if ($hasTableData) {
    $args = array();
    $args[] = $this->_paramTypeList;
    foreach ($tableData as $prop => $val) {
    $args[] = &$tableData[$prop];
    }
    call_user_func_array(array($stmt, 'bind_param'), $args);
    } else {
    if ($this->_where)
    $stmt->bind_param($this->_paramTypeList, $where_value);
    }

    return $stmt;
    }

    /**
    * This helper method takes care of prepared statements' "bind_result method
    * , when the number of variables to pass is unknown.
    *
    * @param object $stmt Equal to the prepared statement object.
    * @return array The results of the SQL fetch.
    */
    protected function _dynamicBindResults($stmt)
    {
    $parameters = array();
    $results = array();

    $meta = $stmt->result_metadata();

    while ($field = $meta->fetch_field()) {
    $parameters[] = &$row[$field->name];
    }

    call_user_func_array(array($stmt, 'bind_result'), $parameters);

    while ($stmt->fetch()) {
    $x = array();
    foreach ($row as $key => $val) {
    $x[$key] = $val;
    }
    $results[] = $x;
    }
    return $results;
    }


    /**
    * Method attempts to prepare the SQL query
    * and throws an error if there was a problem.
    */
    protected function _prepareQuery()
    {
    if (!$stmt = $this->_mysql->prepare($this->_query)) {
    trigger_error("Problem preparing query", E_USER_ERROR);
    }
    return $stmt;
    }


    public function __destruct()
    {
    $this->_mysql->close();
    }

    }
     
  2. colinsp

    colinsp

    Joined:
    Sep 5, 2007
    Messages:
    2,290
    First Name:
    Colin
  3. CilVine

    CilVine Thread Starter

    Joined:
    Apr 7, 2013
    Messages:
    48
    Yep. I agree with you. But, Like you have just said, PDO is probably the way to go right now. I will check out the link you have attached.
     
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