I have a inventory table with the following row data.
Row One -> Barcode : SH9025H36SP23,
Row Two -> Barcode : SH9025H36SP23N1
Both are referred as foreign key in other tables.
Row One is old barcode whereas Row Two is the new barcode.
How do i change Row One to Row Two without loosing any references ?
Thank you for taking your time to answer my question.
Simplified Table Structure for Inventory table
barcode varchar not null
name varchar not null
PRIMARY KEY (barcode)
Referenced by:
TABLE "act" CONSTRAINT "actkey" FOREIGN KEY (fkbarcode) REFERENCES inventory(barcode) ON UPDATE CASCADE ON DELETE RESTRICT
TABLE "do" CONSTRAINT "dokey" FOREIGN KEY (fkbarcode) REFERENCES inventory(barcode) ON UPDATE CASCADE ON DELETE RESTRICT
so on..
Related
Hi all,
Can any understand what's going on here?
The case is:
There are 2 tables, called "matricula" and "pagament" with a 1:1 relationship cardinality.
Table matricula primary key composed by 3 fields "edicio","curs" and "estudiant".
Table pagament primary key, the same as above. Furthermore, it references matricula.
As shown, trying to insert a row in pagament table is rejected because it does not exists a row in table matricula. However, asking for this row returns one result.
What am I missing?
Thanks you all
Carles
The problem is that the order of the fields in both tables is not the same, and, moreover, the restriction of the foreign key in table pagament, said that
foreign key (estudiant,curs,edicio) references matricula
without specifying the matricula fields.
It's been solved by setting this restriction as
foreign key (estudiant,curs,edicio) references matricula(estudiant,curs,edicio)
I have a requirement of deleting records from the Postgres database tables.
We have a Customer table which is the main table, this table contains a primary key which is used in so many other tables as a FOREIGN KEY, I want to delete one of the customers as well as its reference used in other tables. Is there any way to delete the customer from main table as well as from other tables which contains foreign key.
Thanks in Advance.
In the other tables, you want a cascading delete foreign key reference. You can create one in the database using:
alter table othertable add constraint fk_othertable_customerid
foreign key (customerid) references customers(customerid)
on delete cascade;
Note: This assumes that customerid is the name of the column in both tables and that it is already defined in the other tables.
A cascading foreign key constraint does exactly what you specify. When a row is deleted in the reference table, then all related rows are deleted.
If you already have foreign key constraints on customerid, then drop the existing constraint and add the cascading version.
PostgreSQL 11.1
How can "Editing" of a record be transmitted to dependent records?
Summary of my issue:
The master table, disease, needs a unique constraint on the description column. This unique constraint is needed for foreign key ON UPDATE CASCADE to its children tables.
To allow for a temporary violation of the unique constraint, it must be made deferrable. BUT A DEFERABLE CONSTRAINT CAN NOT BE USED IN A FOREIGN KEY.
Here is the situation.
The database has 100+ tables (and keeps on growing).
Most all information has been normalized in that repeating groups of information have been delegated to their own table.
Following normalization, most tables are lists without duplication of records. Duplication of records within a table is not allowed.
All tables have a unique ID assigned to each record (in addition to a unique constraint placed on the record information).
Most tables are dependent on another table. The foreign keys reference the primary key of the table they are dependent on.
Most unique constraints involve a foreign key (which in turn references the primary key of the parent table).
So, assume the following schema:
CREATE TABLE phoenix.disease
(
recid integer NOT NULL DEFAULT nextval('disease_recid_seq'::regclass),
code text COLLATE pg_catalog."default",
description text COLLATE pg_catalog."default" NOT NULL,
CONSTRAINT disease_pkey PRIMARY KEY (recid),
CONSTRAINT disease_code_unique UNIQUE (code)
DEFERRABLE,
CONSTRAINT disease_description_unique UNIQUE (description)
,
CONSTRAINT disease_description_check CHECK (description <> ''::text)
)
CREATE TABLE phoenix.dx
(
recid integer NOT NULL DEFAULT nextval('dx_recid_seq'::regclass),
disease_recid integer NOT NULL,
patient_recid integer NOT NULL,
CONSTRAINT pk_dx_recid PRIMARY KEY (recid),
CONSTRAINT dx_unique UNIQUE (tposted, patient_recid, disease_recid)
,
CONSTRAINT dx_disease_recid_fkey FOREIGN KEY (disease_recid)
REFERENCES phoenix.disease (recid) MATCH SIMPLE
ON UPDATE CASCADE
ON DELETE RESTRICT,
CONSTRAINT dx_patients FOREIGN KEY (patient_recid)
REFERENCES phoenix.patients (recid) MATCH SIMPLE
ON UPDATE CASCADE
ON DELETE RESTRICT
)
(Columns not involved in this question have been removed. :) )
There are many other children tables of disease with the same basic dependency on the disease table. Note that the primary key of the disease table is a foreign key to the dx table and that the dx table uses this foreign key in a unique constraint. Also note that the dx table is just one table of a long chain of table references. (That is the dx table also has its primary key referenced by other tables).
The problem: I wish to "edit" the contents of the parent disease record. By "edit", I mean:
change the data in the description column.
if the result of the change causes a duplication in the disease table, then one of the "duplicated" records will need to be deleted.
Herein lies my problem. There are many different tables that use the primary key of the disease table in their own unique constraint. If those tables ALSO have a foreign key reference to the duplicated record (in disease), then cascading the delete to those tables would be appropriate -- i.e., no duplication of records will occur.
However, if the child table does NOT have a reference to the "correct" record in the parent disease table, then simply deleting the record (by cascade) will result in loss of information.
Example:
Disease Table:
record 1: ID = 1 description = "ABC"
record 2: ID = 2 description = "DEF"
Dx Table:
record 5: ID = 5 refers to ID=1 of Disease Table.
Editing of record 1 in Disease table results in description becoming "DEF"
Disease Table:
record 1: ID = 1 "ABC" --> "DEF"
I have tried deferring the primary key of the disease table so as to allow the "correct" ID to be "cascaded" to the child tables. This causes the following errors:
A foreign key can not be dependent on a deferred column. "cannot use a deferrable unique constraint for referenced table "disease"
additionally, the parent table (disease) has no way of knowing ahead of time if its children already have a reference to the "correct" record so allowing deletion, or if the child needs to change its own column data to reflect the new "correct" id.
So, how can I allow a change in the parent table (disease) and notify the child tables to change their column values -- and delete within them selves should a duplicate record arise?
Lastly, I do not know today what future tables I will need. So I cannot "precode" into the parent table who its children are or will be.
Thank you for any help with this.
I have one table manual_errors_archive. I need to add foreign key to this table keeping reference to values table, values table having 800,000 records and manual_errors_archive table does not have any records.
ALTER TABLE manual_errors_archive
ADD CONSTRAINT fk_manua_reference_value
FOREIGN KEY (value_id)
REFERENCES values;
Postgres version i am using 9.1
But this is running for more than 1 hr after that I canceled the process. Any idea how to optimize this process?
I have two tables like Samp1(Parent Table) and Samp2 (Child table)
Parent Table :Samp1
column Datatype Constraint
----------------------------------------
Id Number(6) Primary Key
Child table :Samp2
column Datatype Constraint
----------------------------------------------
Id Number(6) Foriegn Key
Then how to modify column data type Number to Varchar2(10) both parent and child table at a time, can I?
You can't do this in one step. Assuming the tables have data, you'd probably need to do something like
Add a new column (e.g. id_varchar) to your parent table
Populate the data in this new column from the data in the existing column
Add that new column to the child table
Populate the data in this new column from the data in the existing column
Create a new foreign key constraint for the new column
Drop the existing foreign key constraint
Drop the existing primary key constraint
Drop the existing id columns from both tables
Rename the id_varchar column to id in each table
Create a new primary key constraint on the parent table
Normally, this would require some downtime since you generally don't want sessions modifying data while you're doing this. If you need to do this online, you could potentially use the dbms_redefinition package which would involve creating new copies of both tables.