I am trying to update a table using JPA if I find that record using the primary key.During which I have a restriction should not update the record with null values.If I have a table
Employee with columns emp_id,emp_name
emp_name has a value and the new record does not have the value for emp_name in that case the old name should be retained.Is it possible?
When you find() the original employee it will have the old values. Where does your new record come from? Say it is some detached employee, then simply only overwrite the attributes that are not null into the managed employee.
JPA merge() will always merge everything. In EclipseLink you can set a FetchGroup on an entity being merged, and only the fetched attributes will be merged.
Related
I have two instances of the same database, but data is only committed to the "original" one. I need to copy inserted data from certain tables and commit them to the same tables in the second DB automatically. How can I do it?
I've already created synonyms for the tables in the second DB on original and within a specially prepared trigger I tried to use INSERT INTO ... statement with :new. but it is causing the data to not be committed anywhere and I receive Oracle Errors like:
ORA-02291: integrity constraint (PRDBSHADOW.FK_ED_PHY_ENT) violated.
Here is my trigger code
create or replace TRIGGER INS_COPY_DATA
AFTER INSERT ON ORIGDB.TABLE_A
REFERENCING NEW AS NEW OLD AS OLD
FOR EACH ROW
BEGIN
insert into COPY_TABLE_A(val1,val2,val3,val4) values (:new.val1, :new.val2, :new.val3, :new.val4);
END;
I think the entry in parent table is missing here. At least the FK ending of constraint is telling me so.
It means you need to insert first all the data into a "parent" table in order to be able to insert records in a "child".
For example the table auto_maker is having 3 rows only: Audi, Peugeot, and Honda.
Another table named "model" has 2 columns "maker" and "model". "maker" is a foreign key referencing to the "auto_maker" table.
It means in the models table are only the records allowed whose "maker" column value exists in "auto_maker" table.
In other words only these are available:
maker model
Audi A4
Peugeot 308
Honda Accord
Of course you can enter every model you wish, but "maker" value has to exist in the auto_maker table.
This is what probably happen - the trigger tries to insert a data in a column which is referencing to a "parent" table and the :new value just doesn't exist.
The following script will let you know what table you need to fill first.
select aic.index_owner, aic.table_name, aic.column_name
from all_constraints uc,
all_ind_columns aic
where aic.INDEX_NAME = uc.r_constraint_name
and uc.table_name = 'TABLE_A'
and uc.constraint_type = 'R';
If the query returns something just create similar triggers on those tables with similar logic you already have
I am inserting a record successfully in the database table. The primary key (member_id) is set to auto_increment. I want when I insert a member record and a new member_id is created, to retrieve that same record id immediately from the same query. Is that possible?
Regards,
$this->db->insert_id() will get the latest id from the database.
See: http://ellislab.com/codeigniter/user-guide/database/helpers.html
$this->db->insert('...');
$member_id = mysql_insert_id();
This would work also, its the standart PHP function.
http://www.w3schools.com/php/func_mysql_insert_id.asp
I have two tables employee, department with a one to many relationship such that a column name 'depRefID' in employee references the primary key of the 'department' table.
I have a dojogrid that fetched data from employee table via a Service variable and a select menu that lists the department names.
I've setup an onchange function on the select menu that, would ideally loop each selected row in the employee table and change its foreign key to the one selected via the select widget.
I'm trying to use a separate service variable to update "employee" table using and update query.
How can I reference or access the foreign key 'depRefID' in HQl as directly referencing it throws an exception.
Say there are two tables, Company and Employee. Employee has a foreign key to Company and Company has a foreign key to Employee. How should I insert and delete data into these tables without getting referential integrity errors?
COMPANIES
ID
NAME
CONTACT_EMPLOYEE_ID --FK
EMPLOYEES
ID
NAME
COMPANY_ID --FK
I imagine this is a fairly common problem. I have researched it but have been unable to find much information. Perhaps the problem comes under a more common name I am not aware of.
There are several methods available:
Is the CONTACT_EMPLOYEE_ID column nullable? If it is, just insert company, insert employee and then update the company record.
You could also set one of the constraints as deferrable. You could then set the constraint as deferred, insert both records and then commit.
There are generally 2 strategies:
Leave one of the FKs NULL-able (and then insert NULL into that table, insert row into other table and finally update the NULL).
Defer one of the FKs.
You could even leave both FKs NULL-able or deferrable (or even a combination of the two), so you can perform the insertion in both directions.
You could also consider placing all the EMPLOYEES fields into COMPANIES.
Apart from the other suggestions already made, which are good (make one of the FK columns NULLable, or make the FK constraint deferrable), another one is to make the NOT NULL constraint deferrable, e.g.:
create table COMPANIES (
ID number not null,
NAME varchar2(100) not null,
CONTACT_EMPLOYEE_ID number,
constraint contact_not_null
check (CONTACT_EMPLOYEE_ID not null)
deferrable
initially deferred
);
Now, you can insert a row with NULL for the employee id, insert the employee, then update companies.contact_employee_id with the new employee ID, then COMMIT.
I've Table uses Trigger and sequence to set its PK column.
The Hibernate mapping strategy for its Pk is assigned..
This yields in session.save(obj) returns object with id=0
How to make it returns the correct assigned PK value.
session.getIdentifier() doesn't work!
assigned means: Nobody generates the ID, the ID is set explicitely in the entity before persisting it.
What you want to do is impossible. Hibernate would have to insert an entity without knowing its ID, then the database would generate the ID, and Hibernate would have to reload the entity from the database to know its ID. But how would it reload the entity without knowing its ID?
The native generator does the same thing, and it works because the database provides a getLastGeneratedId() method which allows getting the IOD that the database has generated. But you can't do that with Oracle and a trigger.
Remove the trigger from the database, use the sequence generator, and everything will be fine.