Deprecated: mysql_connect(): The mysql extension is deprecated and will be removed in the future: use mysqli or PDO instead in /home/accuor/public_html/complaints/include/dbconnection.php on line 9

php error happened

Technical information
Error type2
Error descriptionCannot modify header information - headers already sent by (output started at /home/accuor/public_html/complaints/include/dbconnection.php:9)
Error file/home/accuor/public_html/complaints/login.php
Error line6
SQL queryselect TableName,AccessMask from `project5_ugrights` where GroupID in (-3)

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