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.
The length and maximum length of the returned value are the same as the length and maximum length of the parameter.
To return the string aSD1#w in uppercase, use the following clause:
The value returned is ASD1#W.
SQL functions important information
SQL functions are built into Oracle Database and are available for use in various appropriate SQL statements. Do not confuse SQL functions with user-defined functions written in PL/SQL.
If you call a SQL function with an argument of a datatype other than the datatype expected by the SQL function, then Oracle attempts to convert the argument to the expected datatype before performing the SQL function. If you call a SQL function with a null argument, then the SQL function automatically returns null.
The only SQL functions that do not necessarily follow this behavior are