title: Database Exception – yii\db\Exception : could not find driver
body: <p>I am working on Centos in Yii2. I have upgraded php 5.4 to php 7.1.19 but after upgrading it is showing me the error: </p>
  
  <blockquote>
    <p>Database Exception – yii\db\Exception could not find driver Caused by:
    PDOException could not find driver</p>
  </blockquote>
  
  <p>I have added config files in /etc/php.d and /usr/lib64/php/modules but it still gives me the same error.
  I have checked using php -me the extension for pgsql is not available. </p>
  
  <p>Any suggestion would be a great help. Thank you.</p>