I am implementing a form on table that allows the end-user to create a new project. This form contains a shuttle that allows the user to select the disposal site(s)(1+) that the project pertains to. I would like to use the output of the shuttle values to populate an association table between projects and disposal sites which is a many to many relationship.
This is my approach so far:
Created an additional VARCHAR2(4000)in the projects table to store the shuttle output (called 'Shuttle'). The shuttle output in this column looks something like 'CA-AT-D109Z2:CA-AT-D115:CA-AT-D174Z2'.
Created a process to take separate based on ':' and then add the values to the association table using the PL/SQL code:
Declare
Cursor c_values
is
Select
t.column_value As disposal_sites
From
Table ( apex_string.split(:P28_SHUTTLE, ':') ) t
Where
t.column_value Is Not Null;
Begin
for c in c_values loop
insert into MP_MDB_PROJECT_2_DSITE (PROJECTIDFK,DISPOSALSITEIDFK)
values (:P28_PROJECTNUMBER,c.disposal_sites);
end loop;
End;
The process/code enters the values from the shuttle into the association table in a loop as expected for the the disposal site but remains blank for projectidfk (the key that is '1' in the 1:m relationship). The code doesn't throw an error so I am having trouble debugging.
I think perhaps the problem I am having is that project number is computed after submission based on the users selections.Therefore, when the process run it finds :P28_PROJECTNUMBER to be null. Is there a way to ensure the computation to determine :P28_PROJECTNUMBER takes places first and is then followed by the PL/SQL process?
All help appreciated
If the form you're implementing is a native apex form, then you can use the attribute "Return Primary Key(s) after Insert" in the "Automatic Row Processing - DML" process to ensure that the primary key page item contains inserted value for any processes execute after this process.
Just make sure the process that handles the shuttle data is executed after the DML process.
Related
I have 2 Tables :
T_Customer
T_Address
In T_Customer Table have T_Address Foreign Key.
on Web Page Created form Where Customer can add there Details like First Name, Last Name, Address etc.
When Customer Submit form then Adddress details should insert in T_Address table And T_Address ID goes To T_Customer Table is it possible to Create 2 insert operations on one button click?
Is Joins is possible in this?
A single INSERT statement can only affect one table, albeit that you might have some triggers that in turn affect other tables. However, your question was specifically about an action on one button click. This is very possible, and indeed highly advisable. Simply create yourself a single stored procedure and pass it as parameters all the fields required for both Customer and Address tables.
Then within your Stored procedure you can have two inserts, one to Customers and one to Address. If you have a referential integrity constraint, then you must insert customers before address.
The advantage of this approach, is that all commands within a stored procedure are covered by the same transaction: it all succeeds or all fails, and requires only one round trip to the database, in turn being quicker and using less resources.
I need to parameterize a view, and I am doing so by creating a TEMP TABLE which has the parameters for the view.
CREATE TEMP TABLE parms (parm1 INTEGER, parm2 INTEGER);
CREATE VIEW tableview AS ...
The VIEW is rather complex, but it basically uses these two parameters to kick start a recursive CTE, and there isn't any other way that I have found to express the view without these parameters.
The parameters must be stored in a temporary table because each connection should be able to have its own view with different parameters.
In any case, this works fine for creating the view itself, so long as I create the same TEMP TABLE at the start of any queries that use the view, e.g.:
CREATE TEMP TABLE parms (parm1 INTEGER, parm2 INTEGER);
INSERT INTO parms (parm1,parm2) VALUES (5,66);
SELECT * FROM tableview;
I am able to do the same thing to create a trigger to allow inserts on the view:
CREATE TEMP TABLE parms (parm1 INTEGER, parm2 INTEGER);
CREATE TRIGGER tableinsert INSTEAD OF INSERT ON tableview ...
However, when I try to do an actual INSERT (re-creating the TEMP TABLE first as before) I get an error:
no such table: main.parms
If I create a non-temporary table, I do not get this error, but then I have the problem that different connections can't have their own separate views.
I have review the documentation for triggers, and it mentions caveats of using temporary triggers on a non-temporary table, but I don't see anything regarding the reverse.
I did find a reference elsewhere that indicated that "the table... must exist in the same database as the table or view to which the trigger is attached". I thought a temporary table was part of the current database, is this not true? Is there some way to make this true?
I also tried accessing the parms table as temp.parms in the TRIGGER, but got the error:
qualified table names are not allowed on INSERT, UPDATE, and DELETE
statements within triggers
If I can't use a temporary table, is there some way to work around it to accomplish the same thing?
Update: Ok, so it seems to be an SQLite limitation. After digging around a bit in the SQLite source code, it seems to be pretty trivial to allow SELECT access to a temporary table in a trigger. However, allowing UPDATE access appears to be a lot harder.
Temporary objects are created in a separate database named temp, so they are not accessible from triggers in other databases.
The remaining mechanism to get a connection-specific value into a trigger is to use a user-defined function.
I am unsure on how to do this 'best practice' wise.
I have a web application (asp.net VB) that connects to an MS SQL server 2012. Currently when the page loads the app connects to a DB table and gets the last ID and adds 1 to it and displays this to the user. When the user submits the form the new ID is saved to the DB.
The problem being the app may be opened by 2 users at the same time and therefore they will get assigned the same ref number which will cause problems when the data is saved.
How can I assign different numbers to different users if the app is opened at the same time without saving unnecessary data?
You have multiple solutions for this, I'll try to outline a few approaches. (I'll assume that you need to insert things into a DB that I'll call "orders".)
First of all, you can move the ID-generation to the moment when the order is actually inserted, and not at the moment when the user start to enter the data. That way, you do not generate an ID for a user that never completes the form. Also this scenario is easy to accomplish using autoincrementing values in sql server. You can, for example do:
-- create a table with an identity column
create table Orders (
ID int identity(1,1) not null,
Description nvarchar(max) not null
);
-- insert values, without specifying the ID column
insert into Orders (Description) values ()
-- select the row back
-- returns 1, 'My First Order'
select * from Orders;
Another way to do this is to use SQL Server Sequences. These are things that do nothing except generate numbers in a row. They guarantee that the numbers won't be repeated, and always keep count of the current value, i.e.
-- create a sequence
create sequence OrderIdSequence
start with 1
increment by 1;
-- get the next sequence value
select next value for OrderIdSequence
I'd like to use flyway for a DB update with the situation that an DB already exists with productive data in it. The problem I'm looking at now (and I did not find a nice solution yet), is the following:
There is an existing DB table with numeric IDs, e.g.
create table objects ( obj_id number, ...)
There is a sequence "obj_seq" to allocate new obj_ids
During my DB migration I need to introduce a few new objects, hence I need new
object IDs. However I do not know at development time, what ID
numbers these will be
There is a DB trigger which later references these IDs. To improve performance I'd like to avoid determine the actual IDs every time the trigger runs but rather put the IDs directly into the trigger
Example (very simplified) of what I have in mind:
insert into objects (obj_id, ...) values (obj_seq.nextval, ...)
select obj_seq.currval from dual
-> store this in variable "newID"
create trigger on some_other_table
when new.id = newID
...
Now, is it possible to dynamically determine/use such variables? I have seen the flyway placeholders but my understanding is that I cannot set them dynamically as in the example above.
I could use a Java-based migration script and do whatever string magic I like - so, that would be a way of doing it, but maybe there is a more elegant way using SQL?
Many thx!!
tge
If the table you are updating contains only reference data, get rid of the sequence and assign the IDs manually.
If it contains a mix of reference and user data, you need to select the id based on values in other columns.
I am using a global application user account to access database A. This user account does not have permissions to modify database A's schema (ie, create tables, modify tables, etc). This user also has access to database B, but only views. I need to run SQL to feed data from a view in database B into a table in database A.
In a perfect world, I would be able to use this SQL:
create database_a.mytable as (select * from database_b) with no data
However, the user can't create tables in database A. If I could get the DDL of the select statement then I could log in under my personal account (which doesn't have any access to database B) and run the DDL in database A to create the table.
The only other option is to manually write the SQL, but I don't want to do that, especially since this view I am wanting to copy has many columns of varying data types and sizes.
Edit: I may be getting closer. I just experimented with this:
show (select * from database_b.myview)
However, it generated the DLL of every single table that is used in the view itself, as well as the definition for the view. This doesn't really help me since I just want the schema of the select statement itself. In other words, I need what would be generated if I were to use the create table as statement mentioned above.
Edit for Rob: Perhaps "DDL" was the wrong term to use. Using show view db.myview just shows the definition of the view, not the schema it represents. In my above example of create table as, I show how you can create a table that mimics the schema of a result set returned in a select. It generates a DDL on the back end for creating a table and then executes that DDL to actually create the table. You can then say show table db.newtable and see the new table's DDL. I want to get that DDL directly from a select statement so that I can copy it, log out of the app account, into my personal account, and then execute the DDL to create the table.
This is only to save me the headache of having to type out the DDL manually by hand to save time and reduce typing errors, especially since the source view has so many columns. That said, I think hitting up the DBA or writing some snazzy stored procedure to do dynamic stuff would be a bit over the top for my needs. I think there has to be a way to get the DDL for creating a table schema directly from a select statement.
Generate DDL Statements for objects:
SHOW TABLE {DatabaseB}.{Table1};
SHOW VIEW {DatabaseB}.{View1};
Breakdown of columns in a view:
HELP VIEW {DatabaseB}.{View1};
However, without the ability to create the object in the target database DatabaseA your don't have much leverage. Obviously, if the object already existed INSERT INTO SELECT ... FROM DatabaseB.Table1 or MERGE INTO would be options that you already explored.
Alternative Solution
Would it be possible to have a stored procedure created that dynamically created the table based on the view name that is provided? The global application account would simply need privilege to execute the procedure. Generally the user creating the stored procedure would need the permissions to perform the actions contained within the stored procedure. (You have some additional flexibility with this in Teradata 13.10.)
There are some caveats with this approach. You are attempting to materialize views that could reference anywhere from hundreds to billions of records. These aren't simple 1:1 views that are put on top of the target tables. Trying to determine the required space in the target database to materialize the view will be difficult. Performance can and will vary depending on the complexity of the view and the data volumes. This will not be a fast-path or data block optimized operation.
As a DBA, I would be concerned with this approach being taken on by a global application account without fully understanding the intent. I trust you have an open line of communication with the DBA(s) involved for supporting this system. I'm sure there are reasons for your madness that can't be disclosed here.
Possible Solution - VOLATILE TABLE
Unless the implicit privilege for CREATE TABLE has been revoked from the global application account this solution should work.
Volatile tables do not require perm space. There table definitions persist for the duration of the session and any data inserted into them relies on the spool space of the user who instantiated it.
CREATE VOLATILE TABLE {Global Application UserID}.{TableA_Copy} AS
(
SELECT *
FROM {DatabaseB}.{TableA}
)
WITH NO DATA
NO PRIMARY INDEX
ON COMMIT PRESERVE ROWS;
SHOW TABLE {Global Application UserID}.{TableA_Copy};
I opted to use a Teradata 13.10 feature called NO PRIMARY INDEX. By default, CREATE TABLE AS will take the first column of the SELECT statement and make it the PRIMARY INDEX of the table. This could lead to skewing and perm space issues in your testing depending on the data demographics. You can specify an explicit PRIMARY INDEX on your own as you understand the underlying data. (See the DDL manuals for details on the syntax if you're uncertain.)
The use of ON COMMIT PRESERVE ROWS for the intent of this example is probably extraneous. But in reality if you popped any data into that table for testing this clause would be beneficial in Teradata mode as the data would otherwise be lost immediately after the CREATE TABLE or any other data manipulation was performed against the volatile table.