double post entry into db while using function?

double post entry into db while using function?

References

Reference NO 1

http://stackoverflow.com/questions/15165243/double-post-entry-into-db-while-using-function

Reference NO 2

http://stackoverflow.com/questions/14334063/duplicate-entry-insert-in-database-when-using-json-encode-method-in-php

Reference NO 3

http://www.sitepoint.com/forums/showthread.php?933890-prevent-duplicate-entries

Reference NO 4

http://forums.eukhost.com/f19/avoiding-duplicate-database-entries-4711/

Reference NO 5

http://forum.kohanaframework.org/discussion/7174/dbinsert-values-execute-inserting-duplicate-entry/p1

Reference NO 6

http://bytes.com/topic/php/answers/833623-how-can-i-avoid-adding-duplicate-entries-into-database-table

Reference NO 7

http://www.inmotionhosting.com/support/edu/website-design/using-php-and-mysql/php-insert-database

Reference NO 8

http://www.html.net/tutorials/php/lesson19.php