Oracle null and unique constraint - database

Question

Does a unique constraint include a not null constraint?
I have a case that one attribute cellPhone can be NULL but cannot be repeated, so I give it 2 constraints: "not null" and "unique", in a case of updating the record, if user didn't enter a value I put 0 in the field, so it makes this exception:
SEVERE: java.sql.SQLIntegrityConstraintViolationException: ORA-00001: unique constraint (TEST1.OSQS_PARENTS_CELLPHONE_UK) violated
What should I do in the UPDATE case?
EDIT
here's the definition of table ddl
CREATE TABLE "TEST1"."OSQS_PARENTS"
( "PARENT_NO" NUMBER(38,0),
"PARENT_NAME" VARCHAR2(4000 BYTE),
"PARENT_ID" NUMBER(38,0),
"PARENT_EMAIL" VARCHAR2(30 BYTE),
"PARENT_CELLPHONE" NUMBER(38,0)
)
and here's an image of the constraints
and here is the update statement
Parent aParent; //is an object I pass through a function
String SQlUpdate = "UPDATE OSQS_PARENTS P SET P.PARENT_ID=?,P.PARENT_EMAIL=?,P.PARENT_CELLPHONE=?"
+ " where P.PARENT_NO=?";
PreparedStatement pstmt = null;
try {
pstmt = con.prepareStatement(SQlUpdate);
pstmt.setLong(1, aParent.getId());
pstmt.setString(2, aParent.getEmail());
pstmt.setLong(3, aParent.getCellPhoneNo());
pstmt.setLong(4, parentNo);
pstmt.executeUpdate();
}

Answer 1

it sounds like this:
cellPhone must be unique. When user does not input value, you mark it as a 0. Thus it fails when you try to insert multiple 0 values into a 'UNIQUE' column.
I believe you need to drop the NOT NULL constraint on the column (allow it to be UNIQUE yes, but allow NULLS).
Then when user inputs no value, use it as a NO value (unknown = null <> 0 -- 0 is a known value )
throw an IF into your statement, if value then what you have, otherwise SET IT TO NULL!\
pstmt.setNull(3, java.sql.Types.INTEGER);