SQL>
SQL> CREATE TABLE Recipe
(Quantity_used DECIMAL (2,1)
FOREIGN KEY "ICECREAM_ID"
REFERENCES icecreamGT(Icecream_id),
FOREIGN KEY (ingredient_id) REFERENCES ingredient (Ingredient_name),
);
2 3 4 5 6 FOREIGN KEY "ICECREAM_ID"
*
ERROR at line 3:
ORA-00907: missing right parenthesis
UPDATED: new code with adjusted commas and parenthesis
CREATE TABLE Recipe
(
Quantity_used DECIMAL (2,1),
FOREIGN KEY (ID_icecream)
REFERENCES icecreamGT(Icecream_id)
FOREIGN KEY (ID_ingredient)
REFERENCES ingredient(Ingredient_name)
);
Your statement does not have:
An icecream_id column in the recipe table;
An ingredient_id column in the recipe table;
Commas in the correct places;
() Brackets around the "ICECREAM_ID" identifier in the column list of the foreign key.
I.e.:
CREATE TABLE Recipe(
Quantity_used DECIMAL (2,1),
icecream_id NUMBER,
ingredient_id NUMBER,
FOREIGN KEY (ICECREAM_ID) REFERENCES icecreamGT(Icecream_id),
FOREIGN KEY (ingredient_id) REFERENCES ingredient (Ingredient_name)
);
db<>fiddle here
Related
Given this schema:
create table Review2 (
RID varchar(3),
YID varchar(3),
BID varchar(3),
-- other columns
primary key(RID,YID,BID)
);
create table textualContent2(
TID varchar(3),
RID varchar(3) NOT NULL,
-- other columns
primary key (TID),
foreign key (RID) references Review2 on delete cascade
);
I get this error:
ORA-02256: number of referencing columns must match referenced columns
Why is that and how do I fix it?
Review2 has PK:
primary key(RID,YID,BID),
but your FK definition
foreign key (RID) references Review2
uses the shorthand version, which implies referenced columns as being the PK columns (RID,YID,BID), so it's the same as coding:
foreign key (RID) references Review2(RID,YID,BID)
As suggested by the error message:
number of referencing columns must match referenced columns
the number of columns referenced (RID,YID,BID) disagrees those referencing (RID).
To fix the problem, either change your FK to:
foreign key (RID) references Review2(RID)
and define a unique constraint on RID in Review2, or add columns YID and BID to textualContent2 and add them to the FK:
foreign key (RID,YID,BID) references Review2(RID,YID,BID)
I have a very basic question regarding the Keys in SQL. I am trying to write an SQL statement so I can add the foreign key to my tables, however, it would always "table not found or missing". And the reason why I can't create that table is that the next table also has foreign keys from another table that I need to reference. Is there a way around it?
create table table_name (id char (3) primary key, name varchar (8));
SQL > table created.
create table table_name_2 (table2ID char (3) primary key, CID char (3),
name varchar (8), title varchar (8), foreign key (CID) references table_name_3);
SQL > missing table (table_name_3);
create table table_name_3 (CID char (3) primary key, tTitle varchar (8),
foreign key (phone) references table_name_4);
So I was only able to create table 3. What do I need to do so that I can create the table and add the foreign keys referencing while I write the SQL statements?
I am not ALLOWED to use ALTER table.
Create foreign keys separately, using the ALTER TABLE statement. Like this:
SQL> CREATE TABLE table_name(
2 id CHAR(3)PRIMARY KEY,
3 name VARCHAR(8)
4 );
Table created.
SQL> CREATE TABLE table_name_2(
2 table2id CHAR(3)PRIMARY KEY,
3 cid CHAR(3),
4 name VARCHAR(8),
5 title VARCHAR(8)
6 );
Table created.
SQL> CREATE TABLE table_name_3(
2 cid CHAR(3)PRIMARY KEY,
3 ttitle VARCHAR(8)
4 );
Table created.
Now the foreign key:
SQL> ALTER TABLE table_name_2 ADD CONSTRAINT fk_2_3 FOREIGN KEY(cid)
2 REFERENCES table_name_3;
Table altered.
SQL>
one approach you can od is to create the table with the Primary key and then do
and add the foreign key.
ALTER TABLE child_table
ADD CONSTRAINT fk_name
FOREIGN KEY (col1) REFERENCES parent_table(col1);
How can I inherit from two(or more) parent classes in ORACLE SQL? I've tried something like this:
ID(13),
OTHER_ID(9),
CONSTRAINT FK_ID FOREIGN
KEY(ID) REFERENCES TABLE_ONE(ID),
CONSTRAINT FK_OTHER_GROUP FOREIGN
KEY(OTHER_ID) REFERENCES TABLE_TWO(OTHER_ID)
I've read the documentation and the code I've found is this one:
INDEX (product_category, product_id),
INDEX (customer_id),
FOREIGN KEY (product_category, product_id)
REFERENCES product(category, id)
ON UPDATE CASCADE ON DELETE RESTRICT,
FOREIGN KEY (customer_id)
REFERENCES customer(id)
It doesn't quite work for me. Is there any special way to define these indexes? I haven't met them before. The first example had a problem that data types weren't specified. But I'd like someone to explain me how could I do it the second(oracle documentation) way.
This is how I understood the problem:
there are two tables, each having primary key constraint
in my example, those are t_emp and t_dept
there's also the third table whose columns are supposed to reference primary keys from previous two tables
those are fk_th_emp and fk_th_dep foreign key constraints
If that's so, here's how to do that:
SQL> create table t_emp
2 (empno number constraint pk_temp primary key,
3 ename varchar2(20)
4 );
Table created.
SQL> create table t_dept
2 (deptno number constraint pk_dept primary key,
3 dname varchar2(20)
4 );
Table created.
SQL> create table third
2 (id number constraint pk_third primary key,
3 other_id number,
4 --
5 constraint fk_th_emp foreign key (id) references t_emp (empno),
6 constraint fk_th_dep foreign key (other_id) references t_dept (deptno)
7 );
Table created.
SQL>
I use oracle and I try to have a recursive relation
CREATE TABLE "EVENT"
(
"EVENT_ID" NUMBER(18) NOT NULL, //primary key
"NAME" VARCHAR(20) NULL,
"RELATED_EVENT_ID" NUMBER(18) NULL //foreign key
);
Event 1 parent is Event 2....
When I try to create this table, I get this error.
ALTER TABLE "EVENT"
ADD CONSTRAINT "FK_RELATED_EVENT_ID"
FOREIGN KEY ("RELATED_EVENT_ID") REFERENCES "EVENT" ("RELATED_EVENT_ID")
Error report -
SQL Error: ORA-02270: no matching unique or primary key for this column-list
02270. 00000 - "no matching unique or primary key for this column-list"
*Cause: A REFERENCES clause in a CREATE/ALTER TABLE statement
gives a column-list for which there is no matching unique or primary
key constraint in the referenced table.
*Action: Find the correct column names using the ALL_CONS_COLUMNS
catalog view
You have two problems:
There is no primary key constraint on this table.
The foreign key constraint you defined has RELATED_EVENT_ID referencing RELATED_EVENT_ID. I suspect that was just a typo.
Change your table definition to:
CREATE TABLE EVENT
(EVENT_ID NUMBER
NOT NULL
CONSTRAINT PK_EVENT
PRIMARY KEY
USING INDEX,
NAME VARCHAR2(20),
RELATED_EVENT_ID NUMBER);
Then add the foreign key constraint as
ALTER TABLE EVENT
ADD CONSTRAINT EVENT_FK1
FOREIGN KEY (RELATED_EVENT_ID) REFERENCES EVENT(EVENT_ID);
db<>fiddle here
EDIT
Note that the better way to handle this is to use a junction table, such as:
CREATE TABLE EVENT_EVENT
(EVENT_ID1 NUMBER
CONSTRAINT EVENT_EVENT_FK1
REFERENCES EVENT(EVENT_ID),
EVENT_ID2 NUMBER
CONSTRAINT EVENT_EVENT_FK2
REFERENCES EVENT(EVENT_ID),
CONSTRAINT PK_EVENT_EVENT
PRIMARY KEY (EVENT_ID1, EVENT_ID2)
USING INDEX);
Then you can drop the RELATED_EVENT_ID column from EVENT as you no longer need it.
According to oracle document :
Foreign key specifies that the values in the column must correspond to values in a
referenced primary key or unique key column or that they are NULL.
In your case, create primary key on column (EVENT_ID) and use it in reference clause as following:
ALTER TABLE "EVENT"
ADD CONSTRAINT "FK_RELATED_EVENT_ID"
FOREIGN KEY ("RELATED_EVENT_ID")
REFERENCES "EVENT" ("EVENT_ID") -- this
Now, use EVENT2's EVENT_ID as RELATED_EVENT_ID in EVENT1 record to make EVENT2 as parent of EVENT1.
Cheers!!
currently i am facing an oracle constraints issue.
After submiting an insert my foreign key constraint(s) won't fire. What it should do is giving two tables the same ID, but unfortunately only the one table with the primary Key is giving an ID. The column with the foreign key in the second table remains null.
For Instance: Insert into table t1 (t1_id,name, dpt) values (value1 (trigger with autoincrement for id), value2, value3); The same procedure is behind table 2, table 3 ... All constraints are written correctly
Table 1 (Emp)
ID Name Department
1 Joe HR
Table 2 (Projects)
ID Project EmpID
1 new (null) -> must be 1
Thank you in advanced.
Constraint: ALTER TABLE "PROJECTS" ADD CONSTRAINT "EMP_FK" FOREIGN KEY ("EMP_ID")
REFERENCES "EMP" ("EMP_ID") ON DELETE CASCADE ENABLE
Trigger: create or replace TRIGGER Projects_TRG BEFORE
INSERT ON Projects FOR EACH ROW BEGIN :NEW.Project_ID := Projects_SEQ.NEXTVAL;
END;
How do i manage to populate the parent id from the parent table into the child table?
Please note that I used different names in my application.
It appears that you've misunderstood the purpose of a foreign key constraint. A foreign key constraint does NOT automatically propagate constraint values from the parent table to the child table. The purpose of the constraint is to ensure that the values of the key column in the child table, when populated, have matching values in the key column of the parent table. Your application is responsible for ensuring that the key column on the child table is populated with the appropriate value. The constraint doesn't do that for you. It's also perfectly legitimate to have a NULL in the key column of the child table, assuming the the column on the child table doesn't have a NOT NULL constraint on it.