I made a table with one of the columns being a date field. It's unbounded, but using a valuechangelistener and a bean to set the value to some rows in another table programatically. (this table shows the parent, the date is applied to its children). A checkbox in another column depends on this value, being disabled if the date field is empty, enabled when a date is filled in.
When a date is filled in, the bean applies this date to the other table rows and waits for a commit. If I don't commit however, but sort one of the columns, the filled in date disappears.
how could I keep the value in the table?
Related
I am updating a single column in a table using Linq, take fictitious table below.
MyTable (PKID, ColumnToUpdate, SomeRandomColumn)
var row = (from x in DataContext.MyTable
where b.PKID == 5
select x).FirstOrDefault();
row.ColumnToUpdate = 20;
DataContext.SubmitChanges();
This updates the column to as expected, no surprises here. However when I inspect the SQL commands which are generated, it does this:
UPDATE [dbo].[MyTable ]
SET [ColumnToUpdate ] = #p2
WHERE ([PKID] = #p0) AND ([SomeRandomColumn] = #p1)
This is performing the update, but only if all columns have matched the values of what Entity expects them to be, rather than referencing the Primary Key column on it's own.
If a database column is changed by another process, which is very feasible in this particular project; eg. There is a window between getting the row you want to manipulate, calculating the changes you would like to set the value to, and issuing the update command as a batch of rows. In this situation the query will cause an exception, causing a partial update, unless I trap, reload the data and resend individual queries. It also has a downside that the row information can be quite large (ie, containing HTML mark up for instance), and the whole thing gets passed to SQL and slows the system down when larger batches are processed.
Is there a way of making Linq / Entity to issue update commands based only on the PK column in the Where clause?
I never used LINQ-to-SQL for production projects and I never were aware of it applying optimistic concurrency1 by default.
This is the default behavior:
If a table doesn't have a Timestamp/Rowversion column2, all columns have "Update Check" set to "Always" in the DBML (except primary key columns and computed columns, i.e. all updateable columns).
If a table does have a Timestamp/Rowversion column, this column has "Time Stamp" set to "True" in the DBML and all columns have "Update Check" = "Never".
Either "Update Check" or "Time Stamp" mark a column as concurrency token. That's why in update statements you see these additional predicates on (not so) "random" columns. Apparently, the tables in your model didn't have Timestamp/Rowversion columns, hence an update checks the values of all updateable columns in the table.
1 Optimistic concurrency: no exclusive locks are set when updating records, but existing values of all or selected columns are checked while updating. If one of those column value was changed by another user between getting the data and saving them, an update exception occurs.
2 A column of data type Timestamp or Rowversion is automatically incremented when a record is updated and therefore detects all concurrent changes to this record.
I have one field on my form (field example name "completion_date"). This data is stored to table column "completion_date". When users edits the detail, data is overwritten in the backend table field as a default way of storing the data. How can I pass on the existing data in this column to a new column (completion_date_a) when the user saves a new date in the field.
One option is to create a database trigger, e.g.
create or replace trigger trg_bu_date
before update on your_table
for each row
begin
:new.completion_date_a := :old.completion_date;
end;
/
Littlefoots' answer is correct, but you could also do this in apex with very little work. Suppose your form items are P1_COMPLETION_DATE and P1_COMPLETION_DATE_A, both mapped to their respective database column. P1_COMPLETION_DATE_A is hidden. Add a computation to P1_COMPLETION_DATE_A with point "After Header" and type "Item". Pick P1_COMPLETION_DATE as item.
Now when you save the form, the value of P1_COMPLETION_DATE_A will be set to the value of P1_COMPLETION_DATE when it was selected.
In an Hbase table, the row key is like below:
(particular id)_(date with timestamp)
I want to filter the entries in the table with two scenarios:
a. With a particular id - This can be done by ROWPREFIXFILTER
b. All the rows that falls between two dates. Need to compare with the date in the rowkey(after the "_"). I am not sure how this can be achieved.
So the point is I need to have filters to the row key before and after "_".
Thanks in advance
It is just an alternative approach, check if it works.
if you have another lookup table with below mapping (Rowkey -> value),
(date with timestamp)_(particular id) -> (particular id)_(date with timestamp)
a. Use main table for ID lookup
b. for date look up, first get the value / values from lookup table, and use these values to hit main table.
I am implementing a Interactive grid to perform DML operations on a table.
it has combined primary key of two columns
One primary key column is display only and refer to master table and another primary key column I want to have a LOV to select value. LOV is dynamic lov having a display and return value picked from another table.
Inserts are fine but session state item value is set for one row and all the operations are performed on that same row irrespective of which row is selected.
you can see a sample here
https://apex.oracle.com/pls/apex/f?p=128616:2:1964277347439::NO:::
master table name: sample
detail table name: sample_child
primary key in sample child : ID and Name
pop lov is implemented in NAME
LOV values are picked from table: Sample_uncle
LOV display : ID || '-' || NAME
LOV return : ID
you can try to update blabla column of sample_child table to see the issue.
I am not sure how I can give you access to look at the implementation.
I have already tried all the options I can think of
This is to do with your primary keys, the detail table does not appear to have proper ones, thats why it always tried to update the first entry, and I think this is also why every row is marked when you load the table.
Primary keys also do the annoying thing of refusing to be empty, as you can see if you insert a new row, the middle column(which is a PK) is filled with 't1001'.
Since you are dealing with simple tables(and not a whole bunch of joined tables) I always consider it best to use ROWID as PK. So set ROWID as PK for the master table, and ROWID for the detail table. And have the detail table have a Master table be your master table, and then click on the first column in the detail table and set the master column for it. And I also personaly always hide the column that is linked.
I would advise you use ROWID whenever possible as its just so much easier to work with, it does mean you might need to set up a validation to prevent someone adding duplicated values for your actual PK, but since the PK is in the underlying table, they cant enter it anyways(but if you have a validation, the error will be much prettier), whilst if the column is a PK, APEX will prevent duplicates by default.
I hope this helps
I have a Tabular Form in my Oracle Apex application. There is a column as UPDATED_DATE. I have set Tabular Form Attributes of this column as below.
When i'm inserting data, UPDATED_DATE column in database table is filling with a value. But when i'm updating existing record, UPDATED_DATE column is not filling with a new value. old date is remaining without changing to a newer data.
How can i solve this ?
The default will only set a value if the field is empty. On your first entry the field is empty, and therefore the updated_Date is set. On updating, the field is allready set, and therefore won't be updated.
You need to create a dynamic action (assuming you use apex 4 or above) and use that to update the date field. Your dynamic action should be triggerd on change of an table row and subsequently set the date field to the current date.
Let me now if you need help on the dynamic action.