He guys I have the following the tables for ORACLE 10g and the problem is i am trying to enforce entity integrity on ALL tables. I have completed the first 4 but the last one is throwing an error. I have used the following code to alter the tables:
ALTER TABLE name ADD CONSTRAINT name PRIMARY KEY (name);
Actor (actorID, lastName, firstName, middleName, suffix, gender, birthDate, deathDate)
Movie (movieID, title, year, company, totalNoms, awardsWon, DVDPrice, discountPrice)
Quote (quoteID, quote)
Role (roleID ,roleName ,gender ,actorID* ,movieID*)
RoleQuote (roleID*, quoteID*)
for the last table (RoleQuote) i have tried
ALTER TABLE name ADD CONSTRAINT name, name PRIMARY KEY (name, name);
but it is throwing this error:
invalid identifier
Can anyone help me thanks the tables have been created without error and they work flawless but the constraint on the last table (RoleQuote)is not working.
ALTER TABLE table_name ADD CONSTRAINT Constraint_name PRIMARY KEY (Field1_name, Field2_name);
Related
CREATE TABLE Flight (
FlightNo int NOT NULL PRIMARY KEY,
FlightDate Date,
PlaneSerialNo int,
EmployeeID int,
RouteNo int,
CONSTRAINT FK_PlaneSerialNo FOREIGN KEY(PlaneSerialNo)
REFERENCES Plane(PlaneSerialNo),
CONSTRAINT FK_EmployeeID FOREIGN KEY(EmployeeID)
REFERENCES Employee(EmployeeID),
CONSTRAINT FK_RouteNo FOREIGN KEY(RouteNo)
REFERENCES Route(RouteNo)
);
trying to create a sort of database system using oracle where it tracks flights but it just says the name is already used but havent seen any similarities in constraints other than identifying FKs
Oracle doesn't rely much on similarities - it has found object with exactly the same name in its dictionary and - as you can't have two objects with the same name - it raised the error.
Query user_constraints (and then user_objects, if previous search didn't find anything).
If you want to find out which table it is, you might try
select owner, table_name from dba_constraints where constraint_name = '<some value from your create table command>';
Is it possible to specify which is the primary key on creating table as select statement? My aim is to include the declaration of primary key on the create table not modifying the table after the creation.
CREATE TABLE suppliers
AS (SELECT company_id, address, city, state, zip
FROM companies
WHERE company_id < 5000);
Yes, it's possible. You would need to specify columns explicitly:
CREATE TABLE suppliers (
company_id primary key,
address,
city,
state,
zip
)
AS
SELECT company_id, address, city, state, zip
FROM companies
WHERE company_id < 5000;
Here is a demo
Note: in this case primary key constraint will be given a system-generated name. If you want it to have a custom name you'd have to execute alter table suppliers add constraint <<custom constraint name>> primary key(<<primary_key_column_name>>) after executing(without primary key specified) CREATE TABLE suppliers.. DDL statement.
Yes, it's possible.You can try referring below example.
create table student (rollno ,student_name,score , constraint pk_student primary key(rollno,student_name))
as
select empno,ename,sal
from emp;
You can create Suppliers table explicitly and if any column have primary key in companies table, then copy that structure from companies table.
Or
Create a same column defining primary key that you want and copy that column from companies table!
ORDERS table in the Oracle Database:
ORDERS
ORDER_ID NOT NULL NUMBER(4)
ORDATE_DATE DATE
CUSTOMER_ID NUMBER(3)
ORDER_TOTAL NUMBER(7,2)
The ORDERS table contains data and all orders have been assigned a customer ID. I'm trying to add a NOT NULL constraint to the CUSTOMER_ID column. Would I use MODIFY CONSTRAINT or ADD CONSTRAINT? I was told you have to drop the constraint and ADD the new one, but if there is no existing constraint to Customer ID number, would it be MODIFY?
alter table orders modify customer_id not null;
Just MODIFY the column:
alter table orders modify customer_id not null;
Alternatively, you could add an [overkill] constraint in the form:
alter table orders add constraint nn1 check (customer_id is not null);
Just use the first form.
As a side note, some databases (such as Oracle) consider those two constraint different and somewhat separate: the former is a column constraint, while the latter is a table constraint. Oracle keeps track in case you drop one, while the other is still in effect.
I have the following tables:
create table emp_test_lucian as select employee_id,last_name,first_name,department_id from employees;
ALTER TABLE emp_test_lucian
ADD PRIMARY KEY (employee_id);
create table dept_test_lucian as select department_id,department_name from departments_copy;
ALTER TABLE dept_test_lucian
ADD PRIMARY KEY (department_id);
On this tables I want to perform different operations for example: If a department gets deleted (from dept_test_lucian) I will delete all the rows in emp_test_lucian that have that department id with a trigger. This works fine when no fk between the 2 is declared with the following code :
CREATE OR REPLACE TRIGGER triger5
BEFORE UPDATE or DELETE on dept_test_lucian
FOR EACH ROW
BEGIN
IF DELETING then
delete
from emp_test_lucian
where department_id = :OLD.department_id;
else if UPDATING('department_id') then
UPDATE emp_test_lucian
set department_id = :NEW.department_id
where department_id = :OLD.department_id;
END IF;
END IF;
END;
/
What can I add to the code above to work even if I have a fk between the 2 tables like so:
ALTER TABLE emp_test_lucian
ADD CONSTRAINT fk_dep_id FOREIGN KEY(department_id) REFERENCES dept_test_lucian(department_id);
the current code returns :
Error report:
ORA-00001: unique constraint (C##LABORATOR.SYS_C009994) violated
ORA-06512: at line 2
00001. 00000 - "unique constraint (%s.%s) violated"
*Cause: An UPDATE or INSERT statement attempted to insert a duplicate key.
For Trusted Oracle configured in DBMS MAC mode, you may see
this message if a duplicate entry exists at a different level.
*Action: Either remove the unique restriction or do not insert the key.
You need to make clear what table is the 'parent' and what table is the 'child'.
In your example:
- Parent: dept_test_lucian
- Child: emp_test_lucian
Lets call 'dept_test_lucian': TableA
Lets call 'emp_test_lucian': TableB
I come to this conclusion since there is a CONSTRAINT on TableB.department_id" that can only have a value that exists
in "TableA.department_id"
The error message tells you that there is a 'primary key being vialated'.
Primary keys on you tables are:
- "TableA.employee_id"
- "TableB.department_id"
Apparently you are trying to insert a value in one of these columns where that value already exists in.
If '1' is already existing in "TableA.employee_id" you would get such an error.
What I also see in your trigger is:
You have a BEFORE UPDATE Trigger.
So the Trigger looks if there is an UPDATE comming on "TableA" (Parent).
Then you try to UPDATE "TableB" (child) first.
This could be tricky, since "TableB.department_id" can only have values that exist in "TableA.department_id".
If the new UPDATE value doesn't exist in "TableA.department_id", you can not UPDATE that value in "TableB.department_id"
I´ve got this table:
mysql> CREATE TABLE favorite food
-> (person_id SMALLINT UNSIGNED,
->food VARCHAR(20),
->CONSTRAINT pk_favorite_food PRIMARY KEY (person_id, food),
->CONSTRAINT fk_fav_food_person_id FOREIGN KEY (person_id)
->REFERENCES person (person_id)
->);
After execution i get the error 1064. Anybod any ideas what could be wrong?
MySQL Server 6.0
Table name should not have a whitespace in it. Make it something like favorite_food
By searching some possible response on Google, I found this thread on SO... The original table (which is the same as your, but with a nicer formatting) is:
CREATE TABLE favorite_food(
person_id SMALLINT UNSIGNED,
food VARCHAR(20),
CONSTRAINT pk_favorite_food PRIMARY KEY(person_id,food),
CONSTRAINT fk_fav_food_person_id FOREIGN KEY (person_id) REFERENCES person(person_id)
);
You probably don't have the person table, so the foreign key can't be created. (see the last line)
You have remove the _ in the table name (favorite food instead of favorite_food) which is not allowed.