I am using MS Access to connect to a linked Oracle database. I have table B that pulls only certain columns from table A (in the linked DB).
I am trying to execute a macro that runs Query1 to update table B with the data from A that is constantly changing.
The two are not necessarily related by some ID, so the UPDATE TABLE command doesn't seem logical to me. Should I be using JOIN? I just need a place to launch my query from.
Based on the discussion in the comments, it sounds like Table B is simply a "view" on Table A. I am not confident that you need an UPDATE query.
In MS Access, the syntax to create a view is thus:
CREATE VIEW my_view AS
SELECT
col1, col2
FROM
[Table A]
Related
In SQL Server 2008, I need to create a child table from parent big table copying it's values in two columns and updates automatically. These values must be distinct and copy into corresponding two columns in new table. The whole idea would be making reference table with these distinct values and make relation with parent table. Thanks
Enkhzul,
You'll want to create a VIEW. A VIEW will simply run a SELECT query in the background against any tables you request in the query and display as instructed. Syntax will be:
USE [DATABASE]
GO
CREATE VIEW [VIEWNAME] AS
(
select statement here
)
After that you just need to do a SELECT query against the newly created VIEW.
I have two tables A(i,j,k) and B(m,n).
I want to update the 'm' column of B table by taking sum(j) from table A. Is it possible to do it in Vertica?
Following code can be used for Teradata, but does Vertica have this kind of flexibility?
Update B from (select sum(j) as m from A)a1 set m=a1.m;
The Teradata SQL syntax won't work with Vertica, but the following query should do the same thing :
update B set m = (select sum(j) from A)
Depending on the size of your tables, this may not be an efficient way to update data. Vertical is a WORM (write once read many times) store, and is not optimized for updates or deletes.
An alternate way would be to first temporarily move the data in the target table to another intermediate (but not temporary) table. After that write a join query using the other table to produce the desired result, and finally use export table with that join query. Finally drop the intermediate table. Of course, this is assuming you have partitioned your table in a way suitable for your update logic.
I am querying a vendors database that has data that is sharded between multiple tables. The tables are named Events_1, Events_2, Events_3, Events_4 etc.
It appears that a new table is automatically created when the table hits 10,000 records. I am looking to write a query that would be able union the results from all the tables (without having to manually add the tables as they are created) as well as a query to only look at the 2 newest tables.
Any suggestions on the best way to go about this?
The database is Microsoft SQL Server 2008
You can do this with dynamic SQL such that you query sysobjects for table name Events_* and build a SELECT UNION from the results.
Better, though perhaps more complicated, would be a DDL trigger that would dynamically update you UNION VIEW to append the new table whenever a table Events_* was created.
My question is to simple, but I can't find out a way to delete old values of a table and update same table with results of same query.
UPDATE
The query is an SELECT on Table A, and the results be Table B. And nothing on Table B different of the result of last query on Table A.
I have a very big table, and I need to process the records and create a new table regularly. The old values of this table are not important, only the new ones.
I will appreciate any help.
What about a view? If you only need table B to query on. You said you have a select on table A. Lets say your select is SELECT * FROM TableA WHERE X = Y. Then your statement would be
CREATE VIEW vwTableB AS
SELECT * FROM TableA WHERE X = Y
And then instead of querying tableB you would query vwTableB. Any changes to the data in table A would be reflected in the view so you don't have to keep running a script yourself.
This was the data in vwTableB would be kept updated and you wouldn't have to keep deleting and inserting into the second table.
you can use a temporary table to store results you are working with, if you only need it for one session. it will automatically be dropped when you sign out.
you didn't say what db you are using, but try this
create temp tableB AS select * from tableA
There are two Databases, Database A has a table A with columns of id, group and flag. Database B has a table B with columns of ID and flag. Table B is essentially a subset of table A where the group == 'B'.
They are updated/created in odd ways that are outside my understanding at this time, and are beyond the scope of this question (this is not the time to fix the basic setup and practices of this client).
The problem is that when the flag in Table A is updated, it is not reflected in table B, but should be. This is not a time-critical problem, so it was suggested I create a job to handle this. Maybe because it's the end of the week, or maybe because I've never written more than the most basic stored procedure (I'm a programmer, not a DBA), but I'm not sure how to go about this.
At a simplistic level, the stored procedure would be something along of the lines of
Select * in table A where group == B
Then, loop through the resultset, and for each id, update the flag.
But I'm not even sure how to loop in a stored procedure like this. Suggestions? Example code would be preferred.
Complication: Alright, this gets a little harder too. For every group, Table B is in a separate database, and we need to update this flag for all groups. So, we would have to set up a separate trigger for each group to handle each DB name.
And yes, inserts to Table B are already handled - this is just to update flag status.
Assuming that ID is a unique key, and that you can use linked servers or some such to run a query across servers, this SQL statement should work (it works for two tables on the same server).
UPDATE Table_B
SET Table_B.Flag = Table_A.Flag
FROM Table_A inner join Table_B on Table_A.id = Table_B.id
(since Table_B already contains the subset of rows from Table_A where group = B, we don't have to include this condition in our query)
If you can't use linked servers, then I might try to do it with some sort of SSIS package. Or I'd use the method described in the linked question (comments, above) to get the relevant data from Database A into a temp table etc. in Database B, and then run this query using the temp table.
UPDATE
DatabaseB.dbo.Table_B
SET
DatabaseB.dbo.Table_B.[Flag] = DatabaseA.dbo.Table_A.Flag
FROM
DatabaseA.dbo.Table_A inner join DatabaseB.dbo.Table_B B
on DatabaseA.dbo.id = DatabaseB.dbo.B.id
Complication:
For sevaral groups run one such update SQL per group.
Note you can use Flag without []. I'm using the brackets only because of syntax coloring on stackoverflow.
Create an update trigger on table A that pushes the necessary changes to B as A is modified.
Basically (syntax may not be correct, I can't check it right now). I seem to recall that the inserted table contains all of the updated rows on an update, but you may want to check this to make sure. I think the trigger is the way to go, though.
create trigger update_b_trigger
on Table_A
for update
as
begin
update Table_B
set Table_B.flag = inserted.flag
from inserted
inner join Table_B
on inserted.id = Table_B.id
and inserted.group = 'B'
and inserted.flag <> Table_B.flag
end
[EDIT] I'm assuming that inserts/deletes to Table B are already handled and it's just flag updates to Table B that need to be addressed.