I have two identical tables in my database, T1 and T2. T1 is a local table while T2 is a linked table from a live SQL database. At the moment the two tables are identical.
In short, I would like to be able to run a query that will update T1 will all new records that have been added to T2. So once I have run the query, the two tables should be identical again. Is this at all possible? I need to have the data in T1 locally available as I need to be able to query that table even when the data in T2 is not available. The SQL database in question is off site so I will not always be able to run my queries as the link is unreliable.
Any assistance will be greatly appreciated.
If you do have a unique ID for every record and are sure records already entered will never be changed this can actually be quite simple:
INSERT INTO [TBL_INVOICES_LOCAL]
SELECT TBL_INVOICES.*
FROM [TBL_INVOICES_LOCAL] RIGHT JOIN TBL_INVOICES ON [TBL_INVOICES_LOCAL].InvoiceID = TBL_INVOICES.InvoiceID
WHERE ((([TBL_INVOICES_LOCAL].InvoiceID) Is Null));
All you need to do is join the two tables with the relationship being set to:
Include ALL records from LINKED_TABLE and only records from LOCAL_TABLE where the joined fields are equal.
Setting the criteria of the Local Tables ID field to "Is Null" will only show missing records. If you do this in an append query you can update your table in only one query as seen below:
Related
i wanted to compare and identify certain [transaction ids] that exist in one table which is located in server 1 but does not exist in a similar transformed table on a different server (server 2).
These two tables were supposed to be the same but we noticed some transaction ids were missing on the table that is located in server 2. My goal is to identify all the missing transaction ids.
The query that i am looking to write is as below
SELECT
server_1.table_1.[transaction_id] from server_1.table_1
JOIN
server_2.table_2 ON
Table_1.[transaction_id] = Table_2.[transaction_id]
WHERE
server_1.table_1.[transaction_id] NOT IN server_2.table_2.[transaction_id]
one recommendation I have received was
"Let's select the IDs from the source select the result, right click and in SQL complete select general temp table script
Then you can run the scripts on the target server to create a temptable and perform your analysis
Because of the size of the table perhaps you need to do its in batches"
if anyone can help me explain this process as well please?
Thank you very much for your help in advance
i am new for this , i apologize if I have not explained it enough or if i am not clear with my ask
You can do that with a simple OUTER join (LEFT JOIN):
SELECT table1.transaction_id as missing_in_table2
FROM table1 LEFT JOIN table2
ON table1.transaction_id=table2.transaction_id
WHERE table2.transaction_id IS NULL
Using Microsoft SQL server 2017, I want to merge two tables into a 3rd table.
Is there a way to have it defined automatically, without a query?
If it is not possible, I would like to mention that both tables contain a large amount of columns, therefore I look for an efficient query that will not make me write each column name.
Demonstration:
Original tables are Table1,Table2, column structure is as below:
Table1:
(Column1,Column2,Column3)
Table2:
(Column4,Column5,Column6)
My goal is to create Table3. Table3 is based on Table1 LEFT JOIN Table2 ON Column1=Column4.
Table 3:
(Column1,Column2,Column3,Column4,Column5,Column6)
Create it as a view.
CREATE VIEW table3 AS
SELECT Column1,Column2,Column3,Column4,Column5,Column6
FROM Table1 LEFT JOIN Table2 ON Column1=Column4
You can then reference table3 in other queries exactly like an ordinary table.
So there's this table of just about 40,000 rows I am looking to update. Colleague said it's best to incrementally update the table instead of complete delete and load.
So I've tried hashing out the design and logic of a script to do this, but my inexperience is getting to me. I just don't know what's efficient and unneeded to incrementally update a table.
Currently, the warehouse looks like this: data comes from source into a table (let's call this T1) in Teradata. Then it's sent into another table (let's call this T2) in Teradata with some added fields such as timestamp. Lastly, a view is built on that last table for security reasons.
So with that laid out, I was thinking of creating a temp/volatile table with data from T1. This would have all the data up to the time the script is run with new records. Then, go through the entire table seeing if the ID (primary index) already exists in T2, and if not, add it to another temp table. Then somehow combine the second temp table with T2 and override T2 and build a view on top of that.
Does this make any sense?
There's also the possibility of records being updated. So they would already exist in T2, but have updated data in a new version of T1. I think comparing the values of all the columns from T1 to T2 would be highly inefficient, but can't think of another way to do this
A 40,000 row delete and insert should be pretty painless for any modern database. Ditto for updates.
The real reason for doing and incremental delete/update/insert is so you can log the changes and timestamp rows in the permanent table with the date/time of nsertion and/or last update. The usual technique goes something like this:
remove rows from the permanent table that don't exist in the temp table
update rows that exist in both tables
insert rows that exist in the temp table, but don't exist in the permanent table.
Looking at the Teradata docs, that would be something like this (no warranties about this being syntactically correct, since I don't have a Teradata instance to play with):
delete permanent p
where not exists ( select *
from temp t
where t.id = p.id
)
update p
from permanent p ,
temp t
set ...
where t.id = p.id
insert permanent
select ...
from temp t
where not exists ( select *
from permanent p
where p.id = t.id
)
One might note that the deletes might get a little hairy if there are dependent foreign key constraints involved.
One might also note that on the update, the where clause might get a tad...complicated if you want to check for actual changes to column values: not much point in updating a row if nothing has changed.
There's a Teradata MERGE command that you might find useful, check this post:
https://forums.teradata.com/forum/database/merge-syntax-simple-version
merge into merge_tmp as t using (select 1 as a,'stf' as b,'uuj' as c) as s
on t.a = s.a
when matched then update set c = s.c
when not matched then insert values (s.a,s.b,s.c);
If you need to match on more columns simple put an and in the on statement.
Edit: If you want to use MERGE you might also need to use a delete statement like the one in nicholas' post.
I have two tables in my database, one is Transactions and the other is TransactionHistories. The latter is essentially an auditing table, whereby a trigger executes on insert, update and delete on Transactions to capture a screenshot of the data.
I am successfully retrieving all of the data stored in the Transactions table where the columns match, but the difficulty comes where I am trying to retrieve data from another table using a foreign key. For instance:
The transaction table has a field "TransactionType_TransactionTypeId", but in the audit table we wish to store its 'name' equivalent as "TransactionTypeName". This needs to be populated from the "TransactionTypes" table, which has the fields "TransactionTypeId" and "Name".
I am struggling to write a query to retrieve this as we wish. I am trying something similar to the following but having little success:
SELECT #TransactionTypeName=Name
FROM TransactionTypes
WHERE inserted.TransactionType_TransactionTypeId=TransactionTypes.TransactionTypeId;
I'm assuming that is a syntactic nightmare. If someone could point me in the right direction I would be extremely grateful!
well to get a name you should do the following
select #TransactionTypeName = TT.Name
from inserted as i
left outer join TransactionTypes as TT on TT.TransactionTypeId = i.TransactionType_TransactionTypeId
but you have to know that inserted table can have more than one row, and you are getting value for only one row.
I am working on a project where my requirement is just update the database from local server to the destination server (all tables, views, functions, rows and stored procedures).
Now I want to compare the local database table with the destination database table and insert the newly inserted rows from local database to the destination table.
E.g. : I have a database dbsource and dbDestination and both contain a table table1. Now I insert new rows into dbsource.table1.
Now I want to compare both database tables and insert the new rows into the destination table.
Please help me .
Why reinvent the wheel?? There are lots of commercial applications out there that already do this for you:
Red-Gate SQL Data Compare
ApexSQL Data Diff
Assuming both Table1 tables have a Primary Key (unique) column here's how you can implement that. I name the PK column ID:
INSERT INTO DBDESTINATION.<SCHEMA_NAME>.TABLE1
(SELECT T1.* FROM DBSOURCE.<SCHEMA_NAME>.TABLE1 AS T1
LEFT OUTER JOIN DBDESTINATION.<SCHEMA_NAME>.TABLE1 AS T2 ON T1.ID=T2.ID
WHERE T2.ID IS NULL)
Hope that helps.