UCASE or UPPER takes a character expression as a parameter and returns a string in which all alpha characters have been converted to uppercase. The syntax for UPPER case function as given in Oracle documents is as follows.
UCASE or UPPER ( CharacterExpression )
If the parameter type is CHAR , the return type is CHAR. Otherwise, the return type is VARCHAR.
Note: UPPER and LOWER follow the database locale. See territory=ll_CC attribute for more information about specifying locale.
The length and maximum length of the returned value are the same as the length and maximum length of the parameter.