I am fairly new to triggers and PL/SQL, so my question is mainly one of design.
I am creating a set of tables to represent ticket purchases. There are three types of tickets:
Ticket #1: Price, Quantity, Time
Ticket #2: Price, Quantity, Time, Seating, Refundable
Ticket #3: Price, Quantity, Time, Food , Drink
So I have created three tables: (I believe this is called, normalizing):
Table1 has columns Price, Quantity and Time
Table2 has Seating and Refundable
Table3 has Food and Drink
I have inserted a primary key column into Table1 and am using foreign keys in Table2 and Table3 which point to Table1's PK.
The Plan: When a user purchases a ticket, I insert a record into the appropriate table(s). For instance, if the user purchases:
Ticket #1, I insert a record into Table1
Ticket #2, I insert a record into Table1 and Table2
Ticket #3, I insert a record into Table1 and Table3
The Problem: How can I receive all the data for a ticket not of type 1, and then split the parameters to insert into the separate tables. For instance, when I try to create a trigger for Table2, that trigger can only receive the parameters that match what Table2 columns has. How can I receive the data for Table1?
An example of a complete purchase of ticket type 2.
User purchases ticket online -> web form stuff happends... -> dao sends ONE insert command to the database -> trigger for Table2 kicks off and validates info for Table1 and Table2.
Thanks!
You can design this in any way you want, but given that there's not much difference between the ticket types I'd have a single table:
CREATE TABLE TICKET
(ID_TICKET NUMBER
CONSTRAINT PK_TICKET
PRIMARY KEY
USING INDEX,
TICKET_TYPE NUMBER
NOT NULL
CONSTRAINT TICKET_CK1
CHECK(TICKET_TYPE IN (1, 2, 3)),
PRICE NUMBER
NOT NULL,
QUANTITY NUMBER
NOT NULL,
DEPARTURE_TIME DATE
NOT NULL,
SEATING NUMBER
CONSTRAINT TICKET_CK2
CHECK(1 = CASE TICKET_TYPE
WHEN 1 THEN CASE
WHEN SEATING IS NULL
THEN 1
ELSE 0
END
WHEN 2 THEN CASE
WHEN SEATING IS NULL
THEN 0
ELSE 1
END
WHEN 3 THEN CASE
WHEN SEATING IS NULL
THEN 1
ELSE 0
END
END),
REFUNDABLE_INDC CHAR(1)
NOT NULL
CONSTRAINT TICKET_CK3
CHECK(REFUNDABLE_INDC = CASE TICKET_TYPE
WHEN 1 THEN 'N'
WHEN 2 THEN 'Y'
WHEN 3 THEN 'N'
END),
FOOD CHAR(1)
NOT NULL
CONSTRAINT TICKET_CK4
CHECK(FOOD = CASE TICKET_TYPE
WHEN 1 THEN 'N'
WHEN 2 THEN 'N'
WHEN 3 THEN 'Y'
END),
DRINK CHAR(1)
NOT NULL
CONSTRAINT TICKET_CK5
CHECK(DRINK = CASE TICKET_TYPE
WHEN 1 THEN 'N'
WHEN 2 THEN 'N'
WHEN 3 THEN 'Y'
END));
Here CHECK constraints are used to ensure that only the appropriate fields are filled in, based on the ticket type.
Best of luck.
Related
Brief model overview:
I have a student and a course tables. As it's many to many relation there is also a junction table student_course (id_student, id_course), with unique constraint on both columns (composite).
The problem I want to solve:
On account of a mistake, there is no a unique constraint on the code column of the course table. It should as code column should uniquely identify a course. As a result there are two rows in the course table with the same value in the code column. I want to remove that duplicate, check that there is no other duplicates and add a unique constraint on the code column. Without loosing relations with student table.
My approach to solve the issue:
I have create a procedure that should do what I want.
CREATE OR REPLACE PROCEDURE REMOVE_COURSES
(
v_course_code IN VARCHAR2,
v_course_price IN VARCHAR2
)
AS
new_course_id NUMBER;
BEGIN
INSERT INTO course (CODE, PRICE) VALUES (v_course_code, v_course_price)
RETURNING ID INTO new_course_id;
FOR c_course_to_overwrite IN (SELECT *
FROM course
WHERE code = v_course_code AND id != new_course_id) LOOP
UPDATE student_course SET id_course = new_course_id WHERE id_course = c_course_to_overwrite.id;
DELETE FROM course WHERE id = c_course_to_overwrite.id;
END LOOP;
END REMOVE_COURSES;
/
Main problem I want to solve:
The procedure keeps giving me an error about unique constraint violation on student_course table. But I am really not sure how it's possible as I am using new_course_id, so there is no chance that in the junction table there are two rows with the same id_student, id_course. What do I need to fix ?
Miscellaneous:
I want to solve that issue using procedure only for learning purposes
EDITED:
CREATE TABLE student (
id NUMBER GENERATED BY DEFAULT ON NULL AS IDENTITY,
name VARCHAR2(150) NOT NULL,
PRIMARY KEY (id)
);
ALTER TABLE student MODIFY ID
GENERATED BY DEFAULT ON NULL AS IDENTITY (START WITH LIMIT VALUE);
CREATE TABLE course (
id NUMBER GENERATED BY DEFAULT ON NULL AS IDENTITY,
code VARCHAR2(255) NOT NULL,
PRIMARY KEY (id)
);
ALTER TABLE course MODIFY ID
GENERATED BY DEFAULT ON NULL AS IDENTITY (START WITH LIMIT VALUE);
CREATE TABLE student_course (
id_student NUMBER NOT NULL,
id_course NUMBER NOT NULL,
PRIMARY KEY (id_student, id_course),
CONSTRAINT student_fk FOREIGN KEY (id_student) REFERENCES student (id),
CONSTRAINT course_fk FOREIGN KEY (id_course) REFERENCES course (id)
);
insert into student (name) values ('John');
INSERT INTO course (ID, CODE) VALUES (1, 'C_13');
INSERT INTO course (ID, CODE) VALUES (2, 'C_13');
commit;
INSERT INTO STUDENT_COURSE (ID_STUDENT, ID_COURSE) VALUES (1, 1);
INSERT INTO STUDENT_COURSE (ID_STUDENT, ID_COURSE) VALUES (1, 2);
commit;
CALL REMOVE_COURSES('C_13');
[23000][1] ORA-00001: unique constraint (SYS_C0014983) violated ORA-06512: near "REMOVE_COURSES", line 8
Rather than removing one of the duplicate codes, you're creating a third course with the same code, and trying to move all students on either of the old courses onto the new one. The error suggests you have students who are already enrolled on both of the old courses.
Your cursor loop query is:
SELECT *
FROM course
WHERE code = v_course_code AND id != new_course_id
That will find all junction records for both old versions of the code, and the update then sets all of those junction records to the same new ID.
If there are any students listed against both old IDs for the code - which would be allowed by your composite unique key - then they will both be updated to the same new ID.
So say the courses you're looking at are [updated for your example code]:
ID CODE
-- ----
1 C_13
2 C_13
and you have junction records for a student for both courses, like:
ID_STUDENT ID_COURSE
---------- ---------
1 1
1 2
You are creating a new course:
ID CODE
-- ----
3 C_13
Your cursor loop looks for code = 'ABC' and ID != 3, which finds IDs 1 and 2. So in the first iteration of the loop up update the rows with ID 1, so now you have:
ID_STUDENT ID_COURSE
---------- ---------
1 3
1 2
Then in the second iteration you try to update the rows with ID 2, which would attempt to produce:
ID_STUDENT ID_COURSE
---------- ---------
1 3
1 3
which would break the unique constraint - hence the error.
You probably don't want to create a new course at all, but either way, you need to remove duplicate records from student_course - that is, rows which will become duplicates when updated. Basically you need to find students with entries for both existing course IDs, and delete either of them. If you don't care which this would do it:
delete from student_course sc1
where id_course in (
select id
from course
where code = 'C_13'
)
and exists (
select null
from student_course sc2
join course c on c.id = sc.id_course
where sc2.id_student = sc1.id_student
and sc2.id_course > sc1.id_course
and c.code = 'C_13'
);
but there are other (probably better) ways.
You then have the choice of updating all remaining junction records for both old IDs to your new ID; or to consolidate on one of the old IDs and remove the other.
(Your question implies you want to solve the overall task yourself, so I'll refrain from trying to provide a complete solution - this just hopefully helps you understand and resolve your main problem...)
I'm trying to update data in 2 distinct tables in the same query with the following code:
UPDATE (SELECT s.passNumb, a.hour, a.minute, p.number, s.situation
FROM passwords s
JOIN atend a ON s.passNumb = a.passNumb
JOIN points p ON a.number = p.number
WHERE s.passNumb = 1 AND
p.number = 1)
SET a.hour = TO_CHAR(SYSDATE, 'HH24'),
a.minute = TO_CHAR(SYSDATE, 'MI'),
s.situation = 'F';
But I'm getting this error: Cannot modify a column which maps to a non key-preserved table. What am I doing wrong?
A view with a join (or an inline view containing a join in your case) must meet the following conditions to be updatable:
https://docs.oracle.com/cd/B28359_01/server.111/b28286/statements_8004.htm
If you want a join view to be updatable, then all of the following
conditions must be true:
The DML statement must affect only one table underlying the join.
For an INSERT statement, the view must not be created WITH CHECK
OPTION, and all columns into which values are inserted must come from
a key-preserved table. A key-preserved table is one for which every
primary key or unique key value in the base table is also unique in
the join view.
For an UPDATE statement, the view must not be created WITH CHECK
OPTION, and all columns updated must be extracted from a key-preserved
table.
The first condition is rather obvious: The DML statement must affect only one table underlying the join.
But what does it mean: "key preserved table" ?
A key-preserved table is one for which every primary key or unique
key value in the base table is also unique in the join view.
The key preserved table means that each row from this table will appear at most once in the result of a view.
Consider a simple example:
CREATE TABLE users(
user_id int primary key,
user_name varchar(100),
age int
);
insert into users values(1,'Tom', 22);
CREATE TABLE emails(
user_id int,
email varchar(100)
);
Insert into emails values( 1, 'tom#somedomain.com' );
Insert into emails values( 1, 'tom#www.example.org' );
commit;
And a join:
SELECT *
FROM users u
JOIN emails e ON u.user_id = e.user_id;
USER_ID USER_NAME AGE USER_ID EMAIL
---------- --------------- ---------- ---------- --------------------
1 Tom 22 1 tom#somedomain.com
1 Tom 22 1 tom#www.example.org
If you look at a result of this join, it is apparent that:
user_id, user_name and age come from non-key preserved table
email comes from key-preserved table
And now: this update is acceptable, because it updates a key preserved column (table) in this join:
UPDATE (
SELECT * FROM users u
JOIN emails e ON u.user_id = e.user_id
)
SET email = email || '.it' ;
USER_ID USER_NAME AGE USER_ID EMAIL
---------- --------------- ---------- ---------- -------------------------
1 Tom 22 1 tom#somedomain.com.it
1 Tom 22 1 tom#www.example.org.it
But this update cannot be done, since it touches a column from non-key preserved table:
UPDATE (
SELECT * FROM users u
JOIN emails e ON u.user_id = e.user_id
)
SET age = age + 2;
SQL Error: ORA-01779: cannot modify a column which maps to a non key-preserved table
01779. 00000 - "cannot modify a column which maps to a non key-preserved table"
*Cause: An attempt was made to insert or update columns of a join view which
map to a non-key-preserved table.
*Action: Modify the underlying base tables directly.
If you think a while .... Tom appears 2 times in the result of the join (but there is only one Tom in the users table).
When we are trying to update age = age + 2 in this join, then what should be a result of this update ?
Should Tom be updated only once ?
Should Tom be 22+2 = 24 years old after this update ?
Or maybe Tom should be updated twice (since it appears twice in the result of the join) so it should be 22 + 2 + 2 = 26 years old.
Another example - please tell me what should be an outcome of this update?:
UPDATE ( ....our join ... ) SET age = length( email );
There are very difficult questions :)
And because of this Oracle prevents from updating non-key preserved tables.
The error message gives this hint:
*Action: Modify the underlying base tables directly.
This means that we must update this table directly, using a separate UPDATE command:
UPDATE users SET age = age + 2
I've two table in the database, the first one is Person and the second is Pilot. as following:
Person Table:
CREATE TABLE person(
person_id NUMBER PRIMARY KEY,
last_name VARCHAR2(30) NOT NULL,
first_name VARCHAR2(30) NOT NULL,
hire_date VARCHAR2(30) NOT NULL,
job_type CHAR NOT NULL,
job_status CHAR NOT NULL
);
/
INSERT INTO person VALUES (1000, 'Smith', 'Ryan', '04-MAY-90','F', 'I');
INSERT INTO person VALUES (1170, 'Brown', 'Dean', '01-DEC-92','P', 'A');
INSERT INTO person VALUES (2010, 'Fisher', 'Jane', '12-FEB-95','F', 'I');
INSERT INTO person VALUES (2080, 'Brewster', 'Andre', '28-JUL-98', 'F', 'A');
INSERT INTO person VALUES (3190, 'Clark', 'Dan', '04-APR-01','P', 'A');
INSERT INTO person VALUES (3500, 'Jackson', 'Tyler', '01-NOV-05', 'F', 'A');
INSERT INTO person VALUES (4000, 'Miller', 'Mary', '11-JAN-08', 'F', 'A');
INSERT INTO person VALUES (4100, 'Jackson', 'Peter', '08-AUG-11', 'P','I');
INSERT INTO person VALUES (4200, 'Smith', 'Ryan', '08-DEC-12', 'F','A');
COMMIT;
/
Pilot Table:
CREATE TABLE pilot(
person_id NUMBER PRIMARY KEY,
pilot_type VARCHAR2(100) NOT NULL,
CONSTRAINT fk_person_pilot FOREIGN KEY (person_id)
REFERENCES person(person_id)
);
/
INSERT INTO pilot VALUES (1170, 'Commercial pilot');
INSERT INTO pilot VALUES (2010, 'Airline transport pilot');
INSERT INTO pilot VALUES (3500, 'Airline transport pilot');
COMMIT;
/
I'm asked to write a pl/sql block of code that accepts the last name from the user and return the result as following:
1) if the last name is not in the table, it returns all the rows in the table.
2) if the last name is in the table, it shows all of the employee's information.
So far I'm doing well with the code, but I got stuck in the case that there are two employees with the last name. here is the cursor that I wrote:
cursor person_info is
select last_name, first_name, hire_date, job_type, job_status, nvl(pilot_type, '-----------')
from person
full outer join pilot
on person.person_id = pilot.person_id
where upper(last_name) = upper(v_last_name)
group by last_name, first_name, hire_date, job_type, job_status, pilot_type
order by last_name, first_name, hire_date asc;
Logically, there are three cases to be covered:
the first case, when the entered last name is in the table, I return all the rows in the table and that's done.
The second case when there is only one employee with the entered last name, and this case is done as well. The last case when there are more than one employee having the same last name like for example 'Jackson' or 'Smith' in this case, my program crashes and give me the error that my select into statement returns more than one row.
select person_id
into v_n
from person
where upper(last_name) = upper(v_last_name);
if v_n = 1 then
open person_info;
fetch person_info into v_last_name, v_first_name, v_hire_date, v_job_type, v_job_status, v_pilot_type;
Can someone help me in guiding me how to fetch the data correctly? I'm not allowed to create any temporary tables or views.
I'm so sorry for making the problem longer than it should, but I was trying to be as clear as possible in explaining the problem.
Thank you in advance.
if the error is
"ORA-01422 exact fetch returns more than requested number of rows" then I think your answer is here https://asktom.oracle.com/pls/asktom/f?p=100:11:0::::P11_QUESTION_ID:981494932508
If you EXPECT the query to return more than one row, you would code:
for x in ( select * from t where ... )
loop
-- process the X record here
end loop;
Your immediate issue is that you're selecting the matching person_id into a variable, and then seeing if that specific ID is 1. You don't have an actual ID 1 anyway so that check would never match; but it is that querying matching multiple rows that gets the error, as you can't put two matching IDs into a single scalar variable.
The way you've structured it looks like you are trying to count how many matching rows there are, rather than looking for a specific ID:
select count(person_id)
into v_n
from person
where upper(last_name) = upper(v_last_name);
if v_n = 1 then
....
When you do have multiple matches then you will need to use the same mechanism to return all of those as you do when there are no matches and you return all employees. You may find the logic should be in the cursor query rather then in PL/SQL logic. It depends on the details of the assignment though, and how it expects you to return the data in both (or all three) scenarios.
It's also possible you just aren't expected to hit this problem - it isn't clear if the assignment is finding all employees, or only those that are pilots. The issue still exists in general, but with the data you show there aren't any duplicate pilot last names. If you haven't learned about this kind of error yet perhaps you're getting a bit ahead of what your tutor expects.
have two tables A and B both same structure except B has one addition extra column inserting as "null". I need to Retain all data from A in B when I insert like below query it is inserting duplicate values because of that getting "primary Key violation error" when I try to create the "CONSTRAINT PK_Details_A PRIMARY KEY" Please help on this to avoid duplicate values while inserting the records.
Thanks in advance.
Insert into tableB(
id, effectiveDate, endDate
,startDate, Type, salary
,baseSalary, Amount, Amount1
,currency, Percentage, Salary
,Notional
)
select id, effectiveDate, endDate
,startDate, Type, salary
,baseSalary, Amount, Amount1
,currency, Percentage, Salary,null
from tableA;
EDIT
Primary key definition for B copied from comment below:
ALTER TABLE B
ADD CONSTRAINT PK_B
PRIMARY KEY ( oid)
USING INDEX ( CREATE UNIQUE INDEX PK_B ON B ( oid )
I have three tables
TABLE 1
PLANS -> Has all the plans information
COLUMNS:
PLAN_ID
PLAN_NAME
OTHER_DETAILS
(PLAN_ID is the PRIMARY KEY)
TABLE 2
REGISTER ->
COLUMNS:
RUN_ID
PLAN_ID
REGISTER_DETAILS
(RUN_ID AND PLAN_ID) is the primary key
TABLE 3
ELECTION ->
Columns
RUN_ID
PLAN_ID
ELECTION_DETAILS
(RUN_ID AND PLAN_ID) is the primary key
PLAN_ID could be present in either REGISTER (or) ELECTION (or) BOTH tables.
For an input RUN_ID , I need to pick rows in the below format such that if a plan has only register details only REGISTER_DETAILS is picked.
If a plan has both REGISTER_DETAILS and ELECTION_DETAILS then both the details should get returned.
Report Format:
RUN_ID PLAN_ID REGISTER_DETAILS ELECTION_DETAILS
Solution
I tried by joining the tables in below format:
SELECT
..
FROM
PLANS A
LEFT JOIN REGISTER B
ON (A.PLAN_ID = B.PLAN_ID
AND B.RUN_ID = 'Input Run Id')
LEFT JOIN ELECTION C
ON (A.PLAN_ID = C.PLAN_ID
AND C.RUN_ID = 'Input Run Id')
But this is also returning plans that are not present in REGISTER and ELECTION tables.
Can someone please tell what is wrong with the query?
Add
WHERE B.PLAN_ID IS NOT NULL OR
C.PLAN_ID IS NOT NULL
to the end of your query.
Best of luck.