Trying to find a way to write an Oracle trigger that would check before an insert to see if a match was found in the primary column and if so update the row information instead of inserting a new row.
I've looked at before insert. Is there a way to cancel the insert based on criteria inside that block?
I've also looked at using the instead of clause but it requires working on a view.
What is the best way to go about this?
Use a MERGE statement instead of an INSERT.
Use a merge statement.
MERGE INTO <<your table>> t
USING (<<your list of records - can be the result of a SELECT >>)
ON ( <<join between table and list of records >>)
WHEN MATCHED THEN
UPDATE SET << the rows you want to set>>
WHEN NOT MATCHED THEN
INSERT (<<columns of table>>)
VALUES (<<value>>)
https://oracle-base.com/articles/9i/merge-statement
Related
I want to insert a one or more records in table A.
But same record already existing in records with status Active
CREATE PROCEDURE Test
AS
BEGIN
INSERT INTO A (x,y,z,status)
SELECT data FROM A WHERE some condtion;
... Here i want to update table A status column into 'N', if the inserted data already existing in table A Compared with x,y,z column.
EXCETION
---Handled
END;
You can try this:
MERGE INTO target_table t
USING source_table s
ON (t.id = s.id)
WHEN MATCHED THEN
UPDATE SET t.col1 = s.col1
WHEN NOT MATCHED THEN
INSERT (col1, col2) VALUES (s.col1, s.col2);
Documentation Link: https://docs.oracle.com/cd/B28359_01/server.111/b28286/statements_9016.htm#SQLRF01606
What you probably want to do is a merge-statement. The merge statement checks if the dataset already exists. In this case you can formulate an update statement. For example, you could update the status. If not, the new dataset will be inserted.
For further information you should hava a look here.
The merge is the way to go. Another approach is first updating all the rows that match the criteria and after do the insert.
However, if your problem is how to differentiate the 2 rows, use the pseudo-column ROWID.
Is there a way to obtain the value of the primary key in a materialized view that after I update it? I'm using VB to update a table and I'd like to return the key of the row I updated so I can use it in subsequent operations. The view will always contain a single record.
I found the answer. It looks like I just need to execute the "Output Inserted.ID" after my update statement.
For example:
UPDATE MyDB..MyView Set record_locked=1 OUTPUT INSERTED.Id
I have a insert statement on table "test". PK on column x in the table "test".
Now while inserting if duplicate row comes then the same row should get updated instead insert.
How can i achieve this.
Is it possible by dup_val_on_index?
Please help.
First create a copy of the above table without any KEY Columns and follow
Step 1: truncate the table first whenever you encounter a bunch of insert statement comes
Step 2: INSERT the above truncated tables
Step 3: Execute the MERGE statement like below
MERGE INTO TABLE_MAIN M
USING TABLE_MAIN_COPY C
ON (m.id = c.id)
WHEN MATCHED THEN UPDATE SET M.somecol = c.somecol
WHEN NOT MATCHED THEN INSERT (m.id, m.somecol)
VALUES (c.id, c.somecol);
You may incur error while on merger ORA-30926: unable to get a stable set of rows in the source tables when there is two or more rows while on update.
you may avoid that using the GROUP function related to id or like ORA-30926: unable to get a stable set of rows in the source tables
I am using an AFTER INSERT row trigger in Oracle 11g to copy specific columns from one table to another on insert. I have the trigger and insert working ok. The problem I have is that I need to insert the new data from one column to a different column when copying it.
The trigger info reads:
BEGIN
insert into BALES_STORAGE
(CROP,
CUTTING,
DESTINATION,
BALES_MOVED,
DATE_MOVED,
PASTURE,
TARGET_LB_PER_DAY)
values
(:new.CROP,
:new.CUTTING,
:new.MOVING_LOCATION,
:new.BALES_MOVED,
:new.DATE_MOVED,
:new.PASTURE,
:new.TARGET_LB_PER_DAY);
END;
The first table is called "BALES_HARVESTED" and the 2nd table the trigger inserts the selected columns into is called "BALES_STORAGE". I need to insert the :new.MOVING_LOCATION data into the column called DESTINATION on the second table.
So my question is: when using an after insert row trigger, how to I change the column that the data is inserted into?
Thanks for any help.
Matthew
Your trigger code worked just fine for me. Not sure what the problem is. The 3rd column in your INSERT statement does the column mapping correctly.
http://sqlfiddle.com/#!4/2d2fd5/1/1
Maybe you have different structures or foreign key constraints. Could you elaborate on what error you get? Does it produce an ORA- error? or does it simply not produce the desired result, but no error?
I need to create insert and update triggers for view. I also need that sql%rowcount after executing insert/update on one row return 1. In SQL Server I can set nocount to on, then make some operations and then set nocount to off and select one row. How can I do something similar in Oracle.
I need this for mapping that view in NHibernate which expect Affected rows equal 1.
One way to ensure that an update will only affect one row is to create a primary key or a unique constraint on the table. Then use the columns that make up the constraint in the where clause of your update statement.