SQL to split the string based on the space (Example -Split the first_name alone from the complete name , Name 'Pete Mahadevan Sankaran' should give result as 'Pete')

Hi, 

I would like to know the SQL function to split the string based on the space. 

Example 

Column ( Complete Name)

PETE MAHADEVAN SANKARAN 

Expect to have result as PETE

Please help with the SQL function.

Thanks!

Prakash Ms