This question already has an answer here:
Closed 11 years ago.
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adding primary key to sql view
I'm working with a software that requires a primary key in a Oracle view. There is possible to add a Primary key in a Oracle view? If yes, how? I can't google information about this.
The SQL standard unfortunately only permits UNIQUE and PRIMARY KEY constraints on base tables, not views. Oracle permits unique indexes on materialized views but not on views generally.
The only thing that comes in my mind is using a materialized view and then create a unique index on it:
drop materialized view tq84_mat_view;
drop table tq84_table;
create table tq84_table (
a number,
b number
);
create materialized view tq84_mat_view
refresh on commit as
select
a,
sum(b) sum_b
from
tq84_table
group by
a;
create unique index tq84_mat_view_uix on tq84_mat_view (sum_b);
insert into tq84_table values (1, 1);
insert into tq84_table values (2, 2);
insert into tq84_table values (1, 4);
commit;
insert into tq84_table values (2, 3);
commit;
--> ORA-12008: error in materialized view refresh path
--> ORA-00001: unique constraint (SPEZMDBA.TQ84_MAT_VIEW_UIX) violated
While this might be useful, it must be kept in mind that the materialized view, as opposed to a "normal" view occupies space in a tablespace. And of course, the index needs space, too.
This is the way by which you can add a primary key in your view.
CREATE OR REPLACE FORCE VIEW VU_NAME
(
PRIMARY_KEY, NAME_ID, ADDRESS_ID
)
AS
SELECT DISTINCT ROWNUM AS PRIMARY_KEY,
NAME.ID UNIT_ID,
ADDRESS_ID
from table1;
Related
I read a lot about it but didn't found any help on that.
My Situation:
I've two database tables which belongs together. This tables I want to query with EntityFramework. Because Table B contains for EntityFramework the discriminator (for choosing the correct class for Table A) I've created a View which Joins Table A and Table B.
This join is quite simple. But: I want also to store data with that View. The issue is, that EntityFramework also wants to store the discriminator. But this isn't possible because it would update/insert into two tables.
So I've tried to create an "Instead of" trigger to just update/insert Table A (because Table B doesn't matter and will never be updated).
When I created the trigger - everything fine. If I insert something with an SQL Statement - everything is fine. But: If I'm inserting directly in the View (using Oracle SQL Developer) it throws the Exception as below:
ORA-22816 (unsupported feature with RETURNING clause).
If I do the same with EntityFramework I get the same error. Can someone help me?
Below my Code:
Table A and Table B:
CREATE Table "TableA"
(
"ID" Number NOT NULL,
"OTHER_VALUESA" varchar2(255),
"TableB_ID" number not null,
CONSTRAINT PK_TableA PRIMARY KEY (ID)
);
CREATE Table "TableB"
(
"ID" Number NOT NULL,
"NAME" varchar2(255),
"DISCRIMINATOR" varchar2(255),
CONSTRAINT PK_TableB PRIMARY KEY (ID)
);
The Joined View:
Create or Replace View "JoinTableAandB"
(
"ID",
"OTHER_VALUESA",
"TableB_ID",
"DISCRIMINATOR"
) AS
select tableA.ID, tableA.OTHER_VALUESA, tableA.TableB_ID, tableB.DISCRIMINATOR
from TABLEA tableA
inner join TABLEB tableB on tableA.TableB_ID = tableB.ID;
And finally the Trigger:
create or replace TRIGGER "JoinTableAandB_TRG"
INSTEAD OF INSERT ON "JoinTableAandB"
FOR EACH ROW
BEGIN
insert into TABLEA(OTHER_VALUESA, TABLEB_ID)
values (:NEW.OTHER_VALUESA, :NEW.TABLEB_ID);
END;
I've also tried it (to verify if the insert is correct just to enter "NULL" into the trigger instead of insert. But got the same error message.
Does anybody know how to solve this? Or does anybody have a good alternative (better Idea)?
Thanks!
Note: I've also defined a sequence for TableA's ID so that it will be generated automatically.
// Edit:
I found a possible Solution for MS SQL:
https://stackoverflow.com/a/26897952/3598980
But I don't know how to translate this to Oracle... How can I return something from a trigger?
Note: I've also defined a sequence for TableA's ID so that it will be generated automatically.
In EF StoreGenerated keys in Oracle are incompatible with INSTEAD OF triggers. EF uses a RETURNING clause to output the store generated keys, which doesn't work with INSTEAD OF triggers.
I have an Oracle table in a live production environment and the table is over half a gig in size. Is it possible to change this normal Oracle table from being heap organised to index organised or is this only achievable by moving the data from this table to another new table which is index organised? Either way, I would be grateful if you could you please list the steps involved in this procedure.
There is no way to alter a table to make it index-organized table. Instead you can redefine the table(using DBMS_REDEFINITION)or can create new table using CTAS.
Example:
create table t2 (
id number, first_name varchar2(20),
constraint pk_id primary key (id)
)
organization index
as select * from t1;
I never used DBMS_REDEFINITION but with CTAS it is not only step to create table if it is production.
List all indexes, constraints, foreign keys and so on based on system views
Prepare create index, constraints and alter foreign keys statements. prepare list of triggers, procedures that depend on table.
Create table as select (consider lock before that step if you can)
Create all indexes, constraints with prepared statements from step 2
Swap table names and swap foreign keys (this step may cause some errors if you hit insert on foreign keys (if you expect it on that time you should lock the table and tables referencing by foreign key).
Compile dependent objects from 2 (if you locked tables unlock here)
(if you haven't locked on step 3) Insert into table select * from new minus select * from old; or if you have timstamp of inserting row just insert new rows.
I hope the list is complete.
This question already has answers here:
How to create id with AUTO_INCREMENT on Oracle?
(18 answers)
Closed 7 years ago.
I want to add a new auto increment primary column to a existing table which has data. How do I do that?
I first added a column and then try to add a sequence after that, I lost how to insert and make that column as primary key.
Say your table is called t1 and your primary-key is called id
First, create the sequence:
create sequence t1_seq start with 1 increment by 1 nomaxvalue;
Then create a trigger that increments upon insert:
create trigger t1_trigger
before insert on t1
for each row
begin
select t1_seq.nextval into :new.id from dual;
end;
If you have the column and the sequence, you first need to populate a new key for all the existing rows. Assuming you don't care which key is assigned to which row
UPDATE table_name
SET new_pk_column = sequence_name.nextval;
Once that's done, you can create the primary key constraint (this assumes that either there is no existing primary key constraint or that you have already dropped the existing primary key constraint)
ALTER TABLE table_name
ADD CONSTRAINT pk_table_name PRIMARY KEY( new_pk_column )
If you want to generate the key automatically, you'd need to add a trigger
CREATE TRIGGER trigger_name
BEFORE INSERT ON table_name
FOR EACH ROW
BEGIN
:new.new_pk_column := sequence_name.nextval;
END;
If you are on an older version of Oracle, the syntax is a bit more cumbersome
CREATE TRIGGER trigger_name
BEFORE INSERT ON table_name
FOR EACH ROW
BEGIN
SELECT sequence_name.nextval
INTO :new.new_pk_column
FROM dual;
END;
Snagged from Oracle OTN forums
Use alter table to add column, for example:
alter table tableName add(columnName NUMBER);
Then create a sequence:
CREATE SEQUENCE SEQ_ID
START WITH 1
INCREMENT BY 1
MAXVALUE 99999999
MINVALUE 1
NOCYCLE;
and, the use update to insert values in column like this
UPDATE tableName SET columnName = seq_test_id.NEXTVAL
You can use the Oracle Data Modeler to create auto incrementing surrogate keys.
Step 1. - Create a Relational Diagram
You can first create a Logical Diagram and Engineer to create the Relational Diagram or you can straightaway create the Relational Diagram.
Add the entity (table) that required to have auto incremented PK, select the type of the PK as Integer.
Step 2. - Edit PK Column Property
Get the properties of the PK column.
You can double click the name of the column or click on the 'Properties' button.
Column Properties dialog box appears.
Select the General Tab (Default Selection for the first time).
Then select both the 'Auto Increment' and 'Identity Column' check boxes.
Step 3. - Additional Information
Additional information relating to the auto increment can be specified by selecting the 'Auto Increment' tab.
Start With
Increment By
Min Value
Max Value
Cycle
Disable Cache
Order
Sequence Name
Trigger Name
Generate Trigger
It is usually a good idea to mention the sequence name, so that it will be useful in PL/SQL.
Click OK (Apply) to the Column Properties dialog box.
Click OK (Apply) to the Table Properties dialog box.
Table appears in the Relational Diagram.
I'd like to use materialized view on prebuilt table to keep a table in sync before a migration. The data is changing constantly, so the changes between export start and import finish need to be tracked. It goes without saying the table is huge so a complete refresh is too slow.
Steps id like to perform:
Create table on new db.
Create mv log on old db table.
Import data from old db to new db.
Create materialized view on the new db on the prebuild table and keep refresh it from the point when the mv log was created.
The problem is that the moment the materialized view is created the mv log on the old table is purged.
Old DB:
create table kvrtest (id number, cat number);
alter table kvrtest add ( constraint pkkvrtest primary key (id) using index);
insert into kvrtest (id, cat) values (1, 1);
commit;
CREATE MATERIALIZED VIEW LOG ON kvrtest WITH PRIMARY KEY;
insert into kvrtest (id, cat) values (2, 1);
insert into kvrtest (id, cat) values (3, 2);
commit;
select * from MLOG$_KVRTEST; --Yields 2, these should be caught by a fast refresh.
New DB:
create table kvrtest (id number, cat number);
alter table kvrtest add ( constraint pkkvrtest primary key (id) using index);
insert into kvrtest (id, cat) values (1, 1); --Simulate import.
commit;
CREATE MATERIALIZED VIEW kvrtest
ON PREBUILT TABLE WITHOUT REDUCED PRECISION
USING INDEX
REFRESH FORCE ON DEMAND
AS
select * from kvrtest#oldDb;
At this point the mv log is purged
select * from MLOG$_KVRTEST; --Yields 0, a fast refresh from here does not catch these records.
Any suggestions?
when you create new MATERIALIZED VIEW with REFRESH tag log table is clearing, because our view is actually after creating.
CREATE MATERIALIZED VIEW kvrtest
ON PREBUILT TABLE WITHOUT REDUCED PRECISION
USING INDEX
REFRESH FORCE ON DEMAND
AS
if don't want to clear your log table use NEVER REFRESH and then change to REFRESH ON DEMAND like this:
CREATE MATERIALIZED VIEW kvrtest
ON PREBUILT TABLE WITHOUT REDUCED PRECISION
USING INDEX
NEVER REFRESH
AS
select * from kvrtest#oldDb;
let's see our log table
select * from MLOG$_KVRTEST;
we have two rows, nice! and then
ALTER MATERIALIZED VIEW kvrtest
REFRESH ON DEMAND;
then after refresh view log table will clear again.
This question already has answers here:
How to create id with AUTO_INCREMENT on Oracle?
(18 answers)
Closed 7 years ago.
I want to add a new auto increment primary column to a existing table which has data. How do I do that?
I first added a column and then try to add a sequence after that, I lost how to insert and make that column as primary key.
Say your table is called t1 and your primary-key is called id
First, create the sequence:
create sequence t1_seq start with 1 increment by 1 nomaxvalue;
Then create a trigger that increments upon insert:
create trigger t1_trigger
before insert on t1
for each row
begin
select t1_seq.nextval into :new.id from dual;
end;
If you have the column and the sequence, you first need to populate a new key for all the existing rows. Assuming you don't care which key is assigned to which row
UPDATE table_name
SET new_pk_column = sequence_name.nextval;
Once that's done, you can create the primary key constraint (this assumes that either there is no existing primary key constraint or that you have already dropped the existing primary key constraint)
ALTER TABLE table_name
ADD CONSTRAINT pk_table_name PRIMARY KEY( new_pk_column )
If you want to generate the key automatically, you'd need to add a trigger
CREATE TRIGGER trigger_name
BEFORE INSERT ON table_name
FOR EACH ROW
BEGIN
:new.new_pk_column := sequence_name.nextval;
END;
If you are on an older version of Oracle, the syntax is a bit more cumbersome
CREATE TRIGGER trigger_name
BEFORE INSERT ON table_name
FOR EACH ROW
BEGIN
SELECT sequence_name.nextval
INTO :new.new_pk_column
FROM dual;
END;
Snagged from Oracle OTN forums
Use alter table to add column, for example:
alter table tableName add(columnName NUMBER);
Then create a sequence:
CREATE SEQUENCE SEQ_ID
START WITH 1
INCREMENT BY 1
MAXVALUE 99999999
MINVALUE 1
NOCYCLE;
and, the use update to insert values in column like this
UPDATE tableName SET columnName = seq_test_id.NEXTVAL
You can use the Oracle Data Modeler to create auto incrementing surrogate keys.
Step 1. - Create a Relational Diagram
You can first create a Logical Diagram and Engineer to create the Relational Diagram or you can straightaway create the Relational Diagram.
Add the entity (table) that required to have auto incremented PK, select the type of the PK as Integer.
Step 2. - Edit PK Column Property
Get the properties of the PK column.
You can double click the name of the column or click on the 'Properties' button.
Column Properties dialog box appears.
Select the General Tab (Default Selection for the first time).
Then select both the 'Auto Increment' and 'Identity Column' check boxes.
Step 3. - Additional Information
Additional information relating to the auto increment can be specified by selecting the 'Auto Increment' tab.
Start With
Increment By
Min Value
Max Value
Cycle
Disable Cache
Order
Sequence Name
Trigger Name
Generate Trigger
It is usually a good idea to mention the sequence name, so that it will be useful in PL/SQL.
Click OK (Apply) to the Column Properties dialog box.
Click OK (Apply) to the Table Properties dialog box.
Table appears in the Relational Diagram.