I have written the following trigger in SQL server:
create trigger test_trigger
on invoice -- This is the invoice table
for insert
as
declare #invoiceAmount int -- This is the amount specified in the invoice
declare #custNumber int -- This is the customer's id
--use the 'inserted' keyword to access the values inserted into the invoice table
select #invoiceAmount = Inv_Amt from inserted
select #custNumber = cust_num from inserted
update customer
set amount = #invoiceAmount
where Id = #custNumber
Will this be able to run in MS Access or is the syntax different?
The Access database engine (formerly called Jet) does not have triggers and regardless has no control-of-flow syntax e.g. a PROCEDURE must consist of exactly one SQL statement.
Tell us what you really want to do and there could be an alternative syntax.
For example, you could create a new key using a UNIQUE constraint on invoice, (cust_num, Inv_Amt), a FOREIGN KEY customer (id, amount) to reference the new key, a VIEW that joins the two tables on the FOREIGN KEY columns and exposing all four columns, then INSERT into the VIEW rather than the table 'invoice'; you may want to use privileges to prevent INSERTs to the base table but user level security was removed from the new Access 2007 engine (called ACE).
But, if you don’t mind me saying, I think your trigger doesn't reflect a real life scenario. A column vaguely named 'amount' in table 'customer' to hold the most recent invoice amount? What about when the inserted logical table contains rows for more than one customer? As I say, I think you need to tell us what you are really trying to achieve.
Access doesn't have triggers
Your trigger that you show here will bomb out since it does not take into account multirow updates the moment someone updates more than one row (and don't say it won't happen because it will better to practice some defensive coding)
Triggers fire per batch not per row, please read Multirow Considerations for DML Triggers
join inserted pseudo table and the invoice table instead to update the values...that works for 1 and more than 1 row
They may be coming in Access 2010? http://blogs.msdn.com/access/archive/2009/08/13/access-2010-data-macros-similar-to-triggers.aspx
MS Access doesn't have triggers.
That is, the the Access Jet engine (which creates .mdb files). If Access is connecting to a database server, then it will use whatever triggers are in that database.
I've never come across triggers in Access unless it's dealing with ADP on SQL Server. So your answer is yes, it's the same if you're on SQL Server for the backend, and no if the table is stored in Access.
Related
I do not know how to ask this question but my client asked me like this he wants for example he has a database at xxx.xxx.xxx.206 a table named Products but he also has a database at xxx.xxx.xxx.246and also a table called Products.
When he inserts a product at xxx.xxx.xxx.206 it should also be inserted inside Products table in xxx.xxx.xxx.246 automatically.
triggers came to my mind and I know how to make a trigger but... these kind of stuff he is asking is beyond my levels of knowledge using sql server.
How can I achieve such thing? Should I use triggers for this? but even using triggers how can I make that connection to another database?
Trigger can be a solution but when the destination is on another server it cause to reduce the performance.
I suggest you to create a job which transfer new inserted record to another server. Adding a new field is required to product table in xxx.xxx.xxx.206
Alter Table Products Add IsTransfered BIT Default(0)
I describe how to use this new filed in my answer to this question:
Identify new values in Table A and insert them in Table B
I have program that takes user and updates information about him/her in five tables. The process is fairly sophisticated as it takes many steps(pages) to complete. I have logs, sysout and syserr statements that helps me to find sql queries in IDE console but it doesn't have all of them. I've already spend many days to catch other missing queries by debugging but no luck so far. The reason why I am doing this is because I want to automate user information updates so I don't have to go through every page entering user details manually.
I wonder if I could just have some technique that will show me database table changes as I already know table names, by changes I mean whether it was update or insert statements and what exactly changed(column name and value inserted/updated). Any advice is greatly appreciated. I have IBM RAD and DB2 database. Thanks.
In DB2 you can track basic auditing information.
DB2 can track what data was modified, who modified the data, and the SQL operation that modified the data.
To track when data was modified, define your table as a system-period temporal table. The row-begin and row-end columns in the associated history table contain information about when data modifications occurred.
To track who and what SQL modified the data, you can use non-deterministic generated expression columns. These columns can contain values that are helpful for auditing purposes, such as the value of the CURRENT SQLID special register at the time that the data was modified. Possible values for non-deterministic generated expression columns are defined in the syntax for the CREATE TABLE and ALTER TABLE statements.
For example
CREATE TABLE TempTable (balance INT,
userId VARCHAR(100) GENERATED ALWAYS AS ( SESSION_USER ) ,
opCode CHAR(1)
GENERATED ALWAYS AS ( DATA CHANGE OPERATION )
... SYSTEM PERIOD (SYS_START, SYS_END));
The userId column stores who modified the data. This column is defined as a non-deterministic generated expression column that contains the value of SESSION_USER special register.
The opCode column stores the SQL operation that modified the data. This column is defined as a non-deterministic generated expression column and stores a value that indicates the type of SQL operation.
Suppose that you then use the following statements to create a history table for TempTable and to associate that history table with TempTable:
CREATE TABLE TempTable_HISTORY (balance INT, user_id VARCHAR(128) , op_code CHAR(1) ... );
ALTER TABLE TempTable ADD VERSIONING
USE HISTORY TABLE TempTable_HISTORY ON DELETE ADD EXTRA ROW;
Capturing SQL statements for a limited number of tables and a limited time - as far as I understand your problem - could be solved with the DB2 Audit facility.
create audit policy tabsql categories execute status both error type normal
audit <tabname> using policy tabsql
You have to have SECADM rights in theh database and the second command will start the audit process. You can stop it with
audit <tabname> remove policy
Check out the
db2audit
command to configure paths and extract the data from the audit file to a delimited file which then could be loaded again into the database.
The necessarfy tables can be created with the provided sqllib/misc/db2audit.ddl script. You will need the query the EXECUTE table for your SQL details
Please note that audit can capture huge amounts of data so make sure to switch it off again after you have catured the necessary information.
I have a table called Table 1. I'm trying to create an after-insert trigger for a Table 1; whereby, whenever a user enters a record, the trigger will create a new table named after the record that triggered its creation.
Please help, I'm using SQL Server 2008
This sounds super non-relational-database-design-ish. I would heavily advise against this in almost every case. And I say "almost" only to allow for artistic freedom of development, I can't think of a single case where this would be appropriate.
That said, if you do in fact want this, you can use dynamic SQL to create a table.
You can build the SQL in your trigger, but basically you want something like:
EXEC 'CREATE TABLE ' + #tableName + ' (ID INT IDENTITY(1,1))';
Of course, the columns are up to you, but that should get you started.
But while we're at it, what you should (probably) be doing is using a single table with a one-to-many relationship to the table on which your trigger is currently assigned.
For instance, if you have a table Users with a column for email and you're looking to create a table for each user's favorites on your website, you should instead consider adding an identity column for user IDs, then reference that in a single UserFavorites table that has UserId and PostId columns, and the appropriate foreign keys implemented.
I have a dozen tables of whom I want to keep the history of the changes. For every one I created a second table with the ending _HISTO and added fields modtime, action, user.
At the moment before I insert, modify or delete a record in this tables I call ( from my delphi app ) a oracle procedure that copies the actual values to the histo table and then do the operation.
My procedure generates a dynamic sql via DBA_TAB_COLUMNS and then executes the generated ( insert into tablename_histo ( fields s ) select fields, sysdate, 'acition', userid from table_name
I was told that I can not call this procedure from a trigger because it has to select the table the trigger is triggered on. Is this true ? Is it possible to implement what I need ?
Assuming you want to maintain history using triggers (rather than any of the other methods of tracking history data in Oracle-- Workspace Manager, Total Recall, Streams, Fine_Grained Auditing etc.), you can use dynamic SQL in the trigger. But the dynamic SQL is subject to the same rules that static SQL is subject to. And even static SQL in a row-level trigger cannot in general query the table that the trigger is defined on without generating a mutating table exception.
Rather than calling dynamic SQL from your trigger, however, you can potentially write some dynamic SQL that generates the trigger in the first place using the same data dictionary tables. The triggers themselves would statically refer to :new.column_name and :old.column_name. Of course, you would have to either edit the trigger or re-run the procedure that dynamically creates the trigger when a new column gets added. Since you, presumably, need to add the column to both the main table and the history table, however, this generally isn't too big of a deal.
Oracle does not allow a trigger to execute a SELECT against the table on which the trigger is defined. If you try it you'll get the dreaded "mutating table" error (ORA-04091), and while there are ways to get around that error they add a lot of complexity for little value. If you really want to build a dynamic query every time your table is updated (IMO this is a bad idea from the standpoint of performance - I find that metadata queries are often slow, but YMMV) it should end up looking something like
strAction := CASE
WHEN INSERTING THEN 'INSERT'
WHEN UPDATING THEN 'UPDATE'
WHEN DELETING THEN 'DELETE'
END;
INSERT INTO TABLENAME_HISTO
(ACTIVITY_DATE, ACTION, MTC_USER,
old_field1, new_field1, old_field2, new_field2)
VALUES
(SYSDATE, strAction, USERID,
:OLD.field1, :NEW.field1, :OLD.field2, :NEW.field2)
Share and enjoy.
I want to create a table trigger for insert and update. How can I get the values of the current record that is inserted/updated?
within the trigger, you can use a table called 'inserted' to access the values of the new records and the new version of the updated records. Similarly, the table called 'deleted' allows you to access deleted records and the original versions of updated records.
using function 'update' on column ( if you wanna check the fact of update) or retrieving rows from table 'inserted'
While triggers can be used for this, I'd be very careful about deciding to implement them. They are an absolute bear to debug, and can lead to a lack of maintainability.
if you need to do cascading updates (i.e. altering table A in turn changes table B), I would either use a stored procedure (which can be tested and debugged more easily than a trigger), or if you're fortunate enough to be using an ORM (Entity framework, NHibernate, etc.) perform this function within your model or repository.