Trouble calling function

Question

I am having trouble calling simple functions and/or procedures for my database. First of all, here is the DDL to create a single table with a single entry:
CREATE TABLE Security (SSN char(9) NOT NULL, PASSWORD char(10) NOT NULL);
INSERT INTO Security ('123456789', 'mypass');
Now, I want to create a function that takes an SSN and password and returns true if they are associated, and false otherwise. I was able to successfully create the function with no errors using the following:
CREATE OR REPLACE FUNCTION CheckPassword(inSSN VARCHAR2, inPASS VARCHAR2)
RETURN BOOLEAN
IS
valid_pass BOOLEAN;
selected_pass char(10);
BEGIN
SELECT password INTO selected_pass FROM security WHERE ssn=inSSN;
RETURN selected_pass = inPASS;
END CheckPassword;
show errors
However, now I cannot call the function. I have been looking online and the references say to use "call" or "execute", and I have tried both with no luck.
When I try to use "call CheckPassword ('123456789', 'mypass');"
call CheckPassword ('123456789', 'mypass')
ERROR at line 1:
ORA-06576: not a valid function or procedure name
When I try to use "execute CheckPassword ('123456789', 'mypass');"
BEGIN CheckPassword ('123456789', 'mypass'); END;
ERROR at line 1:
ORA-06550: line 1, column 7:
PLS-00221: 'CHECKPASSWORD' is not a procedure or is undefined
ORA-06550: line 1, column 7:
PL/SQL: Statement ignored
It keeps saying undefined or not a valid function or procedure, but it is. I've created it and can see that it is exists and is valid by using "select * from user_objects". I have also tried "call function CheckPassword..." and "execute function CheckPassword..." but neither work. What am I doing wrong?
Thanks
Blake

Answer 1

You've created a function which returns a boolean type. You can't just ignore the return value of a function.
Oh, and another thing...the table you created uses CHAR types, but your function uses VARCHAR2. This can lead to some bugs.
Are you sure you need CHAR types in your table?