pdo_mysql extension is not installed

#0 /home/ddrm/public_html/lib/Zend/Db/Adapter/Abstract.php(441): Varien_Db_Adapter_Pdo_Mysql->_connect()
#1 /home/ddrm/public_html/lib/Zend/Db/Adapter/Pdo/Abstract.php(230): Zend_Db_Adapter_Abstract->query('SET NAMES utf8', Array)
#2 /home/ddrm/public_html/lib/Varien/Db/Adapter/Pdo/Mysql.php(259): Zend_Db_Adapter_Pdo_Abstract->query('SET NAMES utf8', Array)
#3 /home/ddrm/public_html/app/code/core/Mage/Core/Model/Resource/Type/Db/Pdo/Mysql.php(45): Varien_Db_Adapter_Pdo_Mysql->query('SET NAMES utf8')
#4 /home/ddrm/public_html/app/code/core/Mage/Core/Model/Resource.php(85): Mage_Core_Model_Resource_Type_Db_Pdo_Mysql->getConnection(Object(Mage_Core_Model_Config_Element))
#5 /home/ddrm/public_html/app/code/core/Mage/Core/Model/Resource/Setup.php(62): Mage_Core_Model_Resource->getConnection('core_setup')
#6 /home/ddrm/public_html/app/code/core/Mage/Core/Model/Resource/Setup.php(120): Mage_Core_Model_Resource_Setup->__construct('core_setup')
#7 /home/ddrm/public_html/app/code/core/Mage/Core/Model/Config.php(207): Mage_Core_Model_Resource_Setup::applyAllUpdates()
#8 /home/ddrm/public_html/app/code/core/Mage/Core/Model/App.php(242): Mage_Core_Model_Config->init(Array)
#9 /home/ddrm/public_html/app/Mage.php(432): Mage_Core_Model_App->init('', 'store', Array)
#10 /home/ddrm/public_html/app/Mage.php(453): Mage::app('', 'store', Array)
#11 /home/ddrm/public_html/index.php(53): Mage::run()
#12 {main}