This function is used to convert value of column in uppercase . If value of column already in a uppercase then it doesn't covert . It convert only if value of filed is in lowercase .
Syntax :

select ucase ( column_name ) from table_name ;

Syntax for SQL :

select upper ( column_name ) from table_name ;

Example :
Table name : Employee_Info

  Id        Employee_name          Employee_Age               Employee _Salary
  1            Mukesh                  23                           100000
  2            Ayush                   24                           200000
  3            Ishan                   20                           400000
  4            Pranav                  35                           700000
  5            Abhishek                26                           800000
  6            Ravi                    25                           300000
  7            David                   40                           800000

Query to convert column value in uppercase .

select ucase ( Employee_name ) from Employee_Info ;

Output :

 Employee_name
  MUKESH
  AYUSH
  ISHAN
  PRANAV
  ABHISHEK
  RAVI
  DAVID