I have simultaneous request to a particular row in a table and PL/SQL statement is used to update the table by reading the data from master row in the same table and update the current range row and master row it read.
Algorithm is like this:-
Declare
variable declaration
BEGIN
Select (Values) into (values1) from table where <condition1> for update;
select count(*) into tempval from table where <condition2>;
if (tempval == 0) then
insert into table values(values);
else
select (values) into (values2) from table where <condition2> for update;
update table set (values1) where <condition2>;
end if
update table set (values1+incrval) where <condition1>
END;
Unfortunately the master row is updated properly with the correct sequence but the current range picks up the old value of the master range. It does the dirty read. Even though the transaction isolation level for the table is serialized.
Please could some tell me what is happening here?
This is working as designed. Oracle default, and only, read isolation lets the session see all of their own updates. If you perform:
INSERT INTO TABLE1 (col1) values (1);
COMMIT;
UPDATE TABLE1 SET col1 = 2 where col1 = 1;
SELECT col1 FROM TABLE1;
you will see 2 returned from the last query. Please read the Merge Explanation for how to use a MERGE statement to perform the insert or update based upon a single criteria.
Related
I need a help in getting the PLSQL procedure to : Insert/Delete the rows of a table , because as I used Update functionality getting duplicates for that particular Sequence ID field.
So for a particular sequence ID row, whenever I insert the data, it should be the latest in that table.
The last sentence you wrote suggests that you have to
delete row(s) whose ID equals that particular "sequence ID" value
then insert a new row
If you expected some code to be written, you should have posted some more info (CREATE TABLE and INSERT INTO sample data, as well as the way you manipulate it by inserting new row, showing what you expect to happen with old one(s)). It is difficult to write code based on unknown data model.
A guess...
INSERT INTO schema_name.table_name(
primary_key_column
, other_column
)
VALUES(
(SELECT max(primary_key_column)+1 FROM schema_name.table_name),
, 'other_value'
);
COMMIT;
This is the procedure I am using:
https://drive.google.com/file/d/1eGbxSppjexpICKh6pzuW0ZzckVxA6BB0/view?usp=sharing
My requirement when we need to insert the new data , the previous data should be deleted for the corresponding ID.
In the above procedure I am updating the data.
I have two tables TRIP and DRIVER. When a new set of values in inserted into TRIP (to indicate a new trip being made), the values in the column TOTALTRIPMADE (which is currently empty) in the table DRIVER will increase by one. The trigger should recognise which row to update with the select statement I've made.
This is the trigger I've made:
CREATE OR REPLACE TRIGGER updatetotaltripmade
AFTER INSERT ON trip
FOR EACH ROW
ENABLE
BEGIN
UPDATE DRIVER
SET TOTALTRIPMADE := OLD.TOTALTRIPMADE+1
WHERE (SELECT L#
FROM TRIP
INNER JOIN DRIVER
ON TRIP.L# = DRIVER.L#;)
END;
/
However I get this error:
ORA-04098: trigger 'CSCI235.UPDATETOTALTRIPMADE' is invalid and failed re-validation
What should I edit in my code so that my trigger works? Thanks!
One error you made is in trying to reference OLD.TOTALTRIPMADE in your SET clause since no alias OLD exists, and unless the table TRIP contains a TOTALTRIPMADE column then the :OLD record won't contain a TOTALTRIPMADE column either (note that since this is an insert trigger the :OLD record either won't exist or won't contain any meaningful data anyway). Another error is in your WHERE clause where you are selecting L# from TRIP joined to DRIVER, but you aren't linking it back to the DRIVER table that you are attempting to update. Instead just update DRIVER where L# is equal the :NEW value of L# from the trip table. The final error I noticed is your use of , the := assignment operator which is for PLSQL code, however you are using it within SQL so just use = without the colon:
CREATE OR REPLACE TRIGGER updatetotaltripmade
AFTER INSERT ON trip
FOR EACH ROW
ENABLE
BEGIN
UPDATE DRIVER
SET TOTALTRIPMADE = nvl(TOTALTRIPMADE,0)+1
WHERE L# = :NEW.L#;
END;
/
Your code has syntax error due to which the trigger is not compiling,I have modified the trigger and it should get compiled successfully with desired results.Please check and feedback.
Please find below the script to create table and compile the trigger,
drop table trip;
create table trip (trip_id number(10),L# varchar2(10));
drop table driver;
create table driver(driver_id number(10),TOTALTRIPMADE number(10),L# varchar2(10));
drop trigger updatetotaltripmade;
CREATE OR REPLACE TRIGGER updatetotaltripmade
AFTER INSERT ON trip
FOR EACH ROW
ENABLE
DECLARE
BEGIN
UPDATE DRIVER
SET TOTALTRIPMADE = nvl(TOTALTRIPMADE,0) + 1
WHERE DRIVER.L# = :new.L#;
END;
/
select * from ALL_OBJECTS where object_type ='TRIGGER';
Output is below from the tests i did on https://livesql.oracle.com/apex/
There are no issues in the code.The trigger is compiled successfully and is valid.
In my database, i have a trigger which insert the change log entries when a row in Table tblA is updated.
Now, in my code i have to update it through a plain Sql query like
int count = DBContext.ExecuteStoreCommand("<sql query to update records>");
This count variable contains the number of rows affected(no of rows updated + no of rows inserted) due to query.
So my question is, How do i can get only the number of updated rows?
Currently i'm using Entity framework 4. I have looked for solution through connected or disconnected model but couldn't help myself.
int count = DBContext.ExecuteStoreCommand("");
I think you hv to change this to return Select result set
then do this,
<sql query to update>
Select ##RowCount rowcountAffected
Or
suppose your update is
update table1 set col1='foo' where id=2
select count(*) rowcountAffected from table1 where id=2
The most efficient way to return row affected can be
i) Assuming you only update (don't refresh any record after that)
Put Set Nocount ON
Declare #Output parameter inside proc
I get ORA-04091 Error while inserting data into table A. Table A records are refferencing other records in the same table 1:N.
Father records have fk_id = null and child records have fk not null.
create or replace trigger TRBI_A
BEFORE INSERT ON A
for each row
BEGIN
IF :new.fk_id IS NOT NULL then
UPDATE A SET actualTS = CURRENT_TIMESTAMP WHERE id = :new.fk_id;
END IF;
END;
ORA-04091: table name is mutating, trigger/function may not see it
The problem could is probably caused by trigger which tried to modify or query a table that is currently being modified by the statement that fired the trigger.
Does anyone know how to modify the trigger to have it correct?
You know what the problem is, so just read your code a little: you update the same table you are putting the trigger on.
I guess in your case you just need to put :NEW.actualTS:=current_timestamp, without using the update statement.
I want to write a stored procedure (SQL server 2008r2), say I have a table:
person
Columns:
Id int (pk)
Date_of_birth date not null
Phone int allow null
Address int allow null
Name nvarchat(50) not null
Sample data:
Id=1,Date_of_birth=01/01/1987,phone=88888888,address=null,name='Steve'
Update statement in Stored procedure, assume
The parameters are already declare:
Update person set
Date_of_birth=#dob,phone=#phone,address=#address,name=#name where id=#id
The table has a trigger to log any changes.
Now I have an asp.net update page for updating the above person table
The question is, if user just want to update address='apple street' , the above update statement will update all the fields but not check if the original value = new value, then ignore this field and then check the next field. So my log table will log all the event even the columns are not going to be updated.
At this point, my solutions
Select all the value by id and store them into local variables.
Using if-else check and generate the update statement. At last,
dynamically run the generated SQL (sp_executesql)
Select all the value by id and store them into local variables.
Using if-else check and update each field seperately:
If #dob <> #ori_dob
Begin
Update person set date_of_birth=#dob where id=#id
End
May be this is a stupid question but please advice me if you have better idea, thanks!
This is an answer to a comment by the OP and does not address the original question. It would, however, be a rather ugly comment.
You can use a statement like this to find the changes to Address within an UPDATE trigger:
select i.Id, d.Address as OldAddress, i.Address as NewAddress
from inserted as i inner join
deleted as d on d.Id = i.Id
where d.Address <> i.Address
One such statement would be needed for each column that you want to log.
You could accumulate the results of the SELECTs into a single table variable, then summarize the results for each Id. Or you can use INSERT/SELECT to save the results directly to your log table.