I am using Oracle and I'm trying to create foreign key constraints.
Say I have a user table like this:
CREATE TABLE USER (
USER_ID INTEGER GENERATED BY DEFAULT AS IDENTITY,
USERNAME VARCHAR2(30) NOT NULL,
CONSTRAINT USER_PK PRIMARY KEY (USER_ID)
Then I am trying to create table that contains lead_user, delivery_user, and support_user.
I tried both but were not working
1.
CREATE TABLE EXAMPLE (
EXAMPLE_ID INTEGER GENERATED BY DEFAULT AS IDENTITY,
LEAD_USER INTEGER NOT NULL,
DELIVERY_USER INTEGER NOT NULL,
SUPPORT_USER INTEGER NOT NULL,
CONSTRAINT USER_PK PRIMARY KEY (EXAMPLE_ID)
CONSTRAINT FK_USER FOREIGN KEY (LEAD_USER, DELIVERY_USER, SUPPORT_USER) REFERENCES USER(USER_ID)
CREATE TABLE EXAMPLE (
EXAMPLE_ID INTEGER GENERATED BY DEFAULT AS IDENTITY,
LEAD_USER INTEGER NOT NULL,
DELIVERY_USER INTEGER NOT NULL,
SUPPORT_USER INTEGER NOT NULL,
CONSTRAINT USER_PK PRIMARY KEY (EXAMPLE_ID)
CONSTRAINT FK_USER FOREIGN KEY (LEAD_USER, DELIVERY_USER, SUPPORT_USER) REFERENCES USER(USER_ID, USER_ID, USER_ID)
I saw from here
SQLite - Multiple Foreign Keys Referencing the Same Column
that for SQLite, it cannot be done the above way and have to create separate foreign keys such as
CONSTRAINT FK_LEAD_USER FOREIGN KEY (LEAD_USER) REFERENCES USER(USER_ID)
CONSTRAINT FK_DELIVERY_USER FOREIGN KEY (DELIVERY_USER) REFERENCES USER(USER_ID)
CONSTRAINT FK_SUPPORT_USER FOREIGN KEY (SUPPORT_USER) REFERENCES USER(USER_ID)
Does the same applies to Oracle as well?
Related
This question already has an answer here:
ORA-02256: referencing foreign key
(1 answer)
Closed last year.
CREATE TABLE Goft_ForeEver_cus(
customer_Id VARCHAR(10),
first_Name VARCHAR2(20) CONSTRAINT sys_cus_fName_nn NOT NULL,
last_Name VARCHAR2(20) CONSTRAINT sys_cus_lName_nn NOT NULL,
girt_Card_Amount NUMBER(5,2) CONSTRAINT sys_cus_gca_nn NOT NULL,
email VARCHAR2(30) CONSTRAINT sys_cus_email_ck CHECK (email ='%[^a-z,0-9,#,.,_,-]%' ) CONSTRAINT sys_cus_email_nn NOT NULL,
CONSTRAINT sys_cus_pk PRIMARY KEY(customer_Id)
);
ALTER TABLE Goft_ForeEver_cus
ADD CONSTRAINT sys_cus_email_UK UNIQUE (email);
CREATE TABLE Goft_ForeEver_Course_Info(
course_Name VARCHAR2(20),
city VARCHAR2(30) CONSTRAINT sys_courtInf_city_nn NOT NULL,
prov VARCHAR2(20) CONSTRAINT sys_courtInf_prov_nn NOT NULL,
postal_Code VARCHAR2(10) CONSTRAINT sys_courtInf_posC_nn NOT NULL,
star_rating NUMBER(1,1),
discript VARCHAR2(200) CONSTRAINT sys_courtInf_descript_uk UNIQUE,
year_Build DATE CONSTRAINT sys_courtInf_date_nn NOT NULL,
court_length Number(5,2)
CONSTRAINT sys_courtInf_courtL_ck CHECK( court_length = 'YARD')
CONSTRAINT sys_courtInf_courtL_nn NOT NULL,
CONSTRAINT sys_courtInf_pk PRIMARY KEY (course_Name, star_rating )
);
CREATE TABLE Goft_ForeEver_favorite_courses(
course_Name VARCHAR2(20),
customer_Id VARCHAR2(10),
CONSTRAINT sys_favCourt_PK PRIMARY KEY(course_Name,customer_Id),
CONSTRAINT sys_favCourt_FK1 FOREIGN KEY (customer_Id) REFERENCES Goft_ForeEver_cus(customer_Id),
CONSTRAINT sys_favCourt_FK2 FOREIGN KEY (course_Name) REFERENCES Goft_ForeEver_Course_Info(course_Name)
);
);
Error
Error report - ORA-02256: number of referencing columns must match referenced columns 02256. 00000 - "number of referencing columns must match referenced columns" *Cause: The number of columns in the foreign-key referencing list is not equal to the number of columns in the referenced list. *Action: Make sure that the referencing columns match the referenced columns.
It is because Goft_ForeEver_Course_Info has primary key as
CONSTRAINT sys_courtInf_pk PRIMARY KEY (course_Name, star_rating )
while Goft_ForeEver_favorite_courses that references it has foreign key as
CONSTRAINT sys_favCourt_FK2 FOREIGN KEY (course_Name) REFERENCES Goft_ForeEver_Course_Info(course_Name)
See? You're referencing COURSE_NAME, STAR_RATING composite key by COURSE_NAME only - that won't work.
Therefore, either remove STAR_RATING from the primary key in Goft_ForeEver_Course_Info, add STAR_RATING to Goft_ForeEver_favorite_courses, or redesign everything alltogether.
Illustration (SQL*Plus, which points to the error):
SQL> CREATE TABLE Goft_ForeEver_favorite_courses(
2 course_Name VARCHAR2(20),
3 customer_Id VARCHAR2(10),
4 CONSTRAINT sys_favCourt_PK PRIMARY KEY(course_Name,customer_Id),
5 CONSTRAINT sys_favCourt_FK1 FOREIGN KEY (customer_Id) REFERENCES Goft_ForeEver_cus(customer_Id),
6 CONSTRAINT sys_favCourt_FK2 FOREIGN KEY (course_Name) REFERENCES Goft_ForeEver_Course_Info(course_Name)
7 );
CONSTRAINT sys_favCourt_FK2 FOREIGN KEY (course_Name) REFERENCES Goft_ForeEver_Course_Info(course_Name)
*
ERROR at line 6:
ORA-02270: no matching unique or primary key for this column-list
SQL>
The problem here is you have declared the "course_Name" along with "star_rating" column as composite primary key in Goft_ForeEver_Course_Info table whereas you are referencing only one column "course_Name" in sys_favCourt_FK2 foreign key declaration in Goft_ForeEver_favorite_courses table.
I have a DB2 (for IBMi) table created as below. I would like to drop the forign key constraint while running in an SQLRPGLE program. Is this possible?
create table grid_action_details(id integer not null
generated always as identity
(start with 1 increment by 1)
PRIMARY KEY,grid_details_id integer,foreign key(grid_details_id)
references grid_details(id),action_code_details_id integer,
foreign key(action_code_details_id)
references action_code_details(id),action_code_status varchar(2),
created_date date default
current_date,created_by varchar(30),
last_updated_date date default current_date,updated_by
varchar(30),required_parameter clob);
I tried the below syntax but it just doesn't seem to work for me:
ALTER TABLE table-name
DROP FOREIGN KEY foreign_key_name
alter table iesqafile.grid_action_details
drop foreign key action_code_details_id
ACTION_CODE_DETAILS_ID in IESQAFILE type *N not found.
You drop the FK constraint via name, not via column.
Since you didn't specify one during create, you'll need to look to see what name the system generated.
Always a best practice to name things yourself.
CONSTAINT <name> FOREIGN KEY (<columns>)
create table grid_action_details (
id integer not null generated always as identity (
start with 1 increment by 1
)
,constraint grid_action_details_pk
primary key
,grid_details_id integer
,constraint grid_details_fk
foreign key (grid_details_id)
references grid_details (id)
,action_code_details_id integer
,constraint action_code_details_fk
foreign key (action_code_details_id)
references action_code_details (id)
,action_code_status varchar(2)
,created_date date default current_date
,created_by varchar(30)
,last_updated_date date default current_date
,updated_by varchar(30)
,required_parameter clob
);
Now you can drop by the known name
alter table iesqafile.grid_action_details
drop foreign key action_code_details_fk
EDIT
To find the generated name use:
the ACS Schema component
DSPFD
SQL against one of the catalog views (QSYS2.SYSCST, SYSIBM.SQLFOREIGNKEYS, SYSIBM.REFERENTIAL_CONSTRAINTS )
For the Epms table, I want to have only 3 columns (departure_City_Id, arrival_City_Id, Emp_number). However, when I come to insert value, it says that I have 4 columns. The extra one for City_Id. All I want is to avoid having City_Id column in this table. I declare it because I need it just as FK.
CREATE TABLE City (
City_Id char(3),
state varchar(30),
Primary key (City_Id)
);
create table Emps (
Emp_number varchar(30) primary key,
City_Id char(3),
departure_City_Id char(3),
arrival_City_Id char(3),
FOREIGN KEY (City_Id)
REFERENCES City(City_Id),
FOREIGN KEY (City_Id)
REFERENCES City(City_Id)
);
This is pretty straightforward, just specify e.g. , FOREIGN KEY (arrival_city_id) REFERENCES city(city_id) and you'll get an index.
CREATE TABLE emps (
emp_number varchar(30) NOT NULL,
city_id char(3) NOT NULL,
departure_city_id char(3) NOT NULL,
arrival_city_id char(3) NOT NULL,
PRIMARY KEY (emp_number),
KEY city_id (city_id),
KEY departure_city_id (departure_city_id),
KEY arrival_city_id (arrival_city_id),
CONSTRAINT emps_ibfk_1 FOREIGN KEY (city_id) REFERENCES city (city_id),
CONSTRAINT emps_ibfk_2 FOREIGN KEY (departure_city_id) REFERENCES city (city_id),
CONSTRAINT emps_ibfk_3 FOREIGN KEY (arrival_city_id) REFERENCES city (city_id)
) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4;
" I want is to avoid having City_Id column in this table. I declare it because I need it just as FK."
But you don't need it. The foreign key columns are the arrival and departure columns, and those are the ones you must reference in the constraint declarations:
create table Emps (
Emp_number varchar(30) primary key,
departure_City_Id char(3),
arrival_City_Id char(3),
FOREIGN KEY (departure_City_Id)
REFERENCES City(City_Id),
FOREIGN KEY (City_Id)
REFERENCES City(arrival_City_Id)
);
Naming constraints is optional but you may find it helpful when debugging foreign key failures, especially when a table has multiple constraints referencing the same parent key.
while making foreign key in player table it shows following error
ORA-02270: no matching unique or primary key for this column-list
create table person
(
per_ssn number(10) not null,
per_name varchar2(30) not null,
CONSTRAINT pk_PersonID PRIMARY KEY (per_ssn,per_name)
);
create table Player
(
player_ssn number(10) not null,
player_name varchar2(30) not null,
football_club_name varchar2(30) not null,
p_age number(2) not null,
p_weight number(3) not null,
p_height number(10) not null,
country varchar2(20) not null,
p_starting_date date not null,
p_ending_date date not null
);
alter table Player
add constraint player_ssn
FOREIGN KEY (player_ssn)
REFERENCING person (per_ssn)on delete cascade
I want to make two primary keys in person table and then want to refer these
primary keys in player table.
If I make one primary key and then refer it in player table, then it does not show error but I want to make two primary keys.
You should be referencing per_ssn,per_name because that is your PK on person.
Anyway, think about making per_ssn your PK in person table
alter table Player
add constraint player_ssn
FOREIGN KEY (player_ssn,player_name)
REFERENCING person (per_ssn,per_name)on delete cascade
I followed the previous instruction of placing commas after each of the CONSTRAINTS. However, on this table, it's giving me the following error message:
ORA-02264: name already used by an existing constraint
All the foreign key tables that are associated with this table are created successfully. What is missing here?
CREATE TABLE FIELD (
ENCT_ID VARCHAR2(25) NOT NULL,
FLD_NUM NUMBER NOT NULL,
FLD_DESC VARCHAR2(50) NOT NULL,
SYMPT_CODE VARCHAR2(25),
DIAG_CODE VARCHAR2(25),
TEST_ID VARCHAR2(25),
RM_ID VARCHAR2(10) NOT NULL,
AX_CODE VARCHAR2(25) NOT NULL,
PROV_ID VARCHAR2(25) NOT NULL,
MED_NDC VARCHAR2(25),
PRIMARY KEY (ENCT_ID, FLD_NUM),
CONSTRAINT FK_ENCOUNTER FOREIGN KEY (ENCT_ID) REFERENCES ENCOUNTER(ENCT_ID),
CONSTRAINT FK_SYMPTOM FOREIGN KEY (SYMPT_CODE) REFERENCES SYMPTOM(SYMPT_CODE),
CONSTRAINT FK_DIAGNOSIS FOREIGN KEY (DIAG_CODE) REFERENCES DIAGNOSIS(DIAG_CODE),
CONSTRAINT FK_TEST FOREIGN KEY (TEST_ID) REFERENCES TEST(TEST_ID),
CONSTRAINT FK_ROOM FOREIGN KEY (RM_ID) REFERENCES ROOM(RM_ID),
CONSTRAINT FK_ASSESSMENT FOREIGN KEY (AX_CODE) REFERENCES ASSESSMENT(AX_CODE),
CONSTRAINT FK_PROVIDER FOREIGN KEY (PROV_ID) REFERENCES PROVIDER(PROV_ID),
CONSTRAINT FK_MEDICATION FOREIGN KEY (MED_NDC) REFERENCES MEDICATION(MED_NDC));
CREATE TABLE FIELD (
ENCT_ID VARCHAR2(25) PRIMARY KEY,
FLD_NUM NUMBER PRIMARY KEY,
FLD_DESC VARCHAR2(50) NOT NULL,...
Remove any one primary key. It will be the index for the table. Like a School text books have only one index, same way, every table will have only one primary key.