Oracle 11g Release 2

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CREATE TABLE student(
   stu_firstname   VARCHAR(7) NOT NULL PRIMARY KEY
  ,stu_lastname    VARCHAR(5) NOT NULL
  ,stu_sex         VARCHAR(2) NOT NULL
  ,stu_phonenumber VARCHAR(9) NOT NULL
  ,total           INTEGER  NOT NULL
);
INSERT INTO student(stu_firstname,stu_lastname,stu_sex,stu_phonenumber,total) VALUES ('fiendis','plan','M','555 1234',100);
1 rows affected

CREATE VIEW Lubeina_view
AS
SELECT
    stu_firstname   AS First_Name
  , stu_lastname    AS Last_Name
  , stu_sex         AS "Sex"
  , stu_phonenumber AS Phone_Number
  , total           AS Count_of_Placement
FROM student
;
select
*
from Lubeina_view
where sex = 'M'
;
ORA-00904: "SEX": invalid identifier

select
*
from Lubeina_view
where "Sex" = 'M'
;


FIRST_NAME
LAST_NAME
Sex
PHONE_NUMBER
COUNT_OF_PLACEMENT


fiendis
plan
M
555 1234
100


CREATE VIEW Lubeina_view_2
AS
SELECT
    stu_firstname   AS First_Name
  , stu_lastname    AS Last_Name
  , stu_sex         AS Sex
  , stu_phonenumber AS Phone_Number
  , total           AS Count_of_Placement
FROM student
;
select
*
from Lubeina_view_2
where seX = 'M'
;


FIRST_NAME
LAST_NAME
SEX
PHONE_NUMBER
COUNT_OF_PLACEMENT


fiendis
plan
M
555 1234
100


select
*
from Lubeina_view_2
where sEx = 'M'
;


FIRST_NAME
LAST_NAME
SEX
PHONE_NUMBER
COUNT_OF_PLACEMENT


fiendis
plan
M
555 1234
100