I need a sql statement, to insert a new row in one database table and update an existing row in another database table based on some conditions.
Is there a way to do this? To insert a row in one table and update a row in another database table in one sql statement?
Thanks in advance!
Yes, they are called Transactions, and are implemented with START TRANSACTION and COMMIT/ROLLBACK with something like:
START TRANSACTION;
INSERT INTO ...
UPDATE table2 SET name='TOTO' WHERE type=1;
COMMIT;
EDIT
This is not in fact one SQL query, but the operation is done atomically - and I think that is what you need.
A single SQL statement allows you to update one table, not several; if that statement is a MERGE then you can specify insert/update/delete actions but still targeting just the same one target table.
If you just want consistency, use transactions; until a transaction is committed, changes within it are not visible to the outside world.
If you want that a single update (which you cannot control) resulted in a coordinated insert, use an on update trigger in the table being updated. The trigger would insert appropriate row(s) into other table(s).
You can use Trigger to update second table on insert of first table
Yes, it's possible with stored procedures.
Watch this: Stored procedures
Related
is it possible to declare one Sql Trigger Insert, Update, Delete for all tables in the database instead of creating a separate trigger for each table? I just want a simple history of what actions have been taken e.g. TABLE A deletes a row ,TABLE B updates a row ,TABLE C Add new row .. and the trigger will insert a new row to another table with that information I want.
No, a trigger can only be defined on a specified table.
You should read up on the auditing features of SQL Server (http://technet.microsoft.com/en-us/library/cc280386.aspx). They are more performant and more flexible in what you want to achieve. Unfortunately they are not available in the Express Edition.
I need to merge two tables in following way:
Target has one extra Column ID. This Id is coming FROM another Single Column Master Table.
While Inserting the Record in Merge Statement I need to INSERT a new row into mater table and use its id to insert into TARGET table.
I have created a Stored Procedure that Inserts and returns newly inserted ID. Now the Problem is inside SQL Merge, we can't call a stored Proc.
What could be the solution of this issue? Cant use Scalar functions as INSERT can't be performed in Functions.
DECLARE #temp INT
MERGE dbo.mytabletarget T
USING dbo.mytableSource S
ON T.refId=S.RefId
WHEN MATCHED THEN
UPDATE
SET T.col1=S.col1,
T.Col2=S.Col2
WHEN NOT MATCHED BY TARGET THEN
INSERT (Id,col1,col2)
VALUES({Here i need value from SP. SP simply Inserts a new Id into master table and Returns it},S.col1,S.col2);
GO
What could be the solution of this issue?
Do not use a stored procedure. Obvious, isn't it?
For a merge statement, you pretty much are stuck with doing the commands right there in the statement. Merge focuses on ETL loads and has advantages as well as limitations.
Basically, put the logic into the merge statement.
While Inserting the Record in Merge Statement I need to INSERT a new row into mater table
and use its id to insert into TARGET table.
Hm, lookup table maintenance?
The regular approach for that is ti make sure the lookup table is filled first (in a separate statement). ETL (and that is where merge comes from) often works along stages for that particular reason.
Sorry, I do not have a better solution either ;(
The database I am using already has a 2 triggers on part number table (on insert and on update). Insert trigger updates creation date, and update trigger updates modification date.
I have to add 3 more triggers to log updates to this table (on insert, on update and on delete)
In what order they will be executed? Before existing trigger or after? Can I control that?
sp_settriggerorder will allow you to set first or last trigger.
If you have more than two and the order matters, combine them into one trigger and split the functionality over the stored procedures.
can anyone tell that how to update some records of a table without using update statement. it is possible using select statement.
I don't think you can update the table without update statement.
It is not possible with a select statement.
You can delete a row and insert the same row + your changes which is in many ways like an update, but will cause lots of trouble with foreign keys.
Oh, and your DBA might kill you.
You can use
REPLACE INTO tablename(primary key, ...{rest of the columns in the table})
VALUES(the same primary key, new values );
This will delete the previous row and insert a new row with the same primary key and updated column values. Not so much worthwhile, but maybe there is some other way.
It depends what tools you are using and what you actually want to achieve.
There are libraries which allow you to update data you got from a select statement. (eg. ORM's like NHibernate, I think ADO.NET also). These libraries are writing the update statements for you
You can use functions or triggers which change data when you just perform a select statement. In these functions or trigger, you still have an update statement.
For security reasons, you have to make sure that nobody injects an update statement into your select statement. So it is not just save to only perform a select statement.
how to update some records of a table
without using update statement.
Use a MERGE statement.
it is possible using select statement.
Logically, an update is a delete and an insert: INSERT INTO..SELECT to a staging table, modifying the data as appropriate, then DELETE then INSERT INTO..SELECT from staging table.
On the off chance you were asking how this happened when a module ran a select statement it created, then you need to read up on SQL injection. You cannot do an update without an update statment of some kind (includiing not only update but doing delete and then insert or useiing merge) and the user must have update permission on a table, but you can add an update to a select statement that is dymanically created if you haven't correctly parametized it to avoid SQL injection.
If I have a statement
that updates multiple rows, only the trigger will fire only on the first or last row that is being updated (not sure which one). I need to make a trigger that fires for ALL the records that are being updated into a particular table
Assuming SQL Server, A trigger only fires once per update, regardless of the number of rows that are updated. If you need to carry out some additional logic based on updates to multiple rows you can access the changed records by looking at the INSERTED and DELETED logical tables that are accessible in the context of a trigger.
You have not specified the database .....
In Oracle a trigger can be defined to fire for individual rows and based on the type of transaction:
CREATE OR REPLACE TRIGGER BIUDR_MY_TABLE
BEFORE INSERT OR UPDATE OR DELETE
ON MY_TABLE
REFERENCING NEW AS NEW OLD AS OLD
FOR EACH ROW
DECLARE
pk PLS_INTEGER;
BEGIN
etc ....
You just need to indicate if your trigger needs to be executed "FOR EACH ROW" or "FOR EACH STATEMENT". Adding one of these two clauses in the trigger definition will tell the DBMS when to execute the trigger (most, but not all, DBMSs support it). If you don't indicate this clause then the DBMS uses the default option which in your case seems to be the FOR EACH STATEMENT option, and that's why your trigger only fires one for each update sentence, regardless of how many rows you are updating