I'm having trouble getting this compound insert to work in my MERGE statement between two tables (Ignore the when match condition, I know its bad practice). The issue I'm having is getting the ServerId field in the target table to fill. The Team field is filling fine but all of the rows have a null value for ServerId. I can't find an example online for this so I'm hoping someone can help. I don't seem to have any syntactical errors and I know the column 'ServerName' in the Source table is filled for all rows.
MERGE ApplicationTeams AS Target
USING TempApplicationTeams AS Source
ON (Target.ServerId = (SELECT ID from Servers WHERE Name='Source.ServerName') AND Target.Team = Source.Team)
WHEN MATCHED THEN
UPDATE SET Target.Team = Target.Team
WHEN NOT MATCHED BY TARGET THEN
INSERT (ServerId, Team) VALUES((SELECT ID from Servers WHERE Name='Source.ServerName'), Source.Team)
WHEN NOT MATCHED BY SOURCE THEN
DELETE
;
Thanks.
I think you should remove the single quoutes on the where clausule.
You wrote:
(SELECT ID from Servers WHERE Name='Source.ServerName')
But I think you should write this:
(SELECT ID from Servers WHERE Name=Source.ServerName)
And make sure the select id returns only one row otherwise the statement will fail
I hope it will be usefully
Related
I have a query that has as the output the following table (2 columns). What it means, is that I'm going to use the result to wrap it inside a merge into statement.
INSERT_COLUMNS UPDATE_COLUMNS
BANK_NAME target.BANK_NAME = source.BANKNAME
What I'm talking about is this:
with sql_prepare_merge as (
SELECT *
FROM another_table
),
MERGE INTO bank_raw AS target
USING bank AS source
ON source.id = target.id
WHEN MATCHED THEN
UPDATE SET (select update_columns from sql_prepare_merge)
WHEN NOT MATCHED THEN
INSERT (select insert_columns from sql_prepare_merge)
VALUES (source.id, (select insert_columns from sql_prepare_merge));
Keep in mind that the "sql_prepare_merge" is the name from the CTE where I'm getting the table I shared with you - and it has much more code in it, but they don't help here. So, I'm planning to take the text resulting from the subquery and insert it inside the merge statement.
So far, the error I'm getting is: syntax error line 19 at position 4 unexpected 'WHEN'.. By the way, this is inside Snowflake.
Unfortunately this is not possible as per my understanding of the docs: https://docs.snowflake.com/en/sql-reference/sql/merge.html#notmatchedclause-for-inserts
In the non matched clause for inserts you can specify only such values/expressions, refer to the source relations. This means you somehow need to adjust your source part itself (e.g. by joining the initial source with another_table). If this is not possible, you would need to go for separate INSERT and UPDATE statements.
I am using SQL Server 2012 and have two tables with identical structure. I want to insert new records from table 1 to table 2 if they don't already exist in table 2.
If they already exist, I want to update all of the existing records in table 2.
There are some 30 columns in my tables and I want to update all of them.
Can someone please help with this? I had a look at various links posted over internet, but quite don't understand how my statement should look like.
It's really not that hard....
You need:
a source table (or query) to provide data
a target table to merge it into
a condition on which those two tables are checked
a statement what to do if a match (on that condition) is found
a statement what to do if NO match (on that condition) is found
So basically, it's something like:
-- this is your TARGET table - this is where the data goes into
MERGE dbo.SomeTable AS target
-- this is your SOURCE table where the data comes from
USING dbo.AnotherTable AS source
-- this is the CONDITION they have to "meet" on
ON (target.SomeColumn = source.AnotherColumn)
-- if there's a match, so if that row already exists in the target table,
-- then just UPDATE whatever columns in the existing row you want to update
WHEN MATCHED THEN
UPDATE SET Name = source.Name,
OtherCol = source.SomeCol
-- if there's NO match, that is the row in the SOURCE does *NOT* exist in the TARGET yet,
-- then typically INSERT the new row with whichever columns you're interested in
WHEN NOT MATCHED THEN
INSERT (Col1, Col2, ...., ColN)
VALUES (source.Val1, source.Val2, ...., source.ValN);
I've found a lot of near misses on this question. So many similar, but not quite right, scenarios. No doubt my ignorance will shine here.
Using DB2 and a shred of knowledge, my scenario is as follows:
On a table, insert a row of data if a given value is not present in a given column, or update the corresponding row if the value is present.
I have a table
id, bigint, not nullable
ref,varchar, nullable
I am not sure if a MERGE is the correct path here as most examples and thorough discussions all seem to revolve around merging one table into another. I'm simply gathering user input and either adding it or updating it. It seems like it should be really simple.
I'm using jdbc and prepared statements to get this done.
Is MERGE the correct way to do this?
When testing my query in DB2 Control Center, I run up against
"No row was found for FETCH, UPDATE or DELETE; or the result of a
query is an empty table"
or a variety of other errors depending on how I structure my MERGE. Here's what I have presently.
merge into table1 as t1
using (select id from table1 group by id) as t2
on t1.id = t2.id
when matched then update set t1.ref = 'abc'
when not matched then insert (t1.id, t1.ref) values (123, 'abc');
If I were to instead compose an update followed by an insert; for new data the insert runs and the update fails, and for existing data they both succeed resulting in bad data in the table, e.g. two identical rows.
The desired result is if on initial use with the values:
id = 1
ref = a
a new row is added. On subsequent use if the values change to:
id = 1
ref = b
the row with id = 1 is updated. Subsequent uses would follow the same rules.
Please let me know how I can phrase this question better.
Update id is not an automatic incrementing key. It's an external key that will be unique but not every thing we are referencing will need a related row in the table I'm attempting to update. This table is rather unstructured on its own but is part of a larger data model.
I'm a bit puzzled by your query. Reading the text makes me suspect that you want something like this:
merge into table1 as t1
using ( values (123, 'abc') ) as t2 (id, ref)
on t1.id = t2.id
when matched then update
set t1.ref = t2.ref
when not matched then
insert (id, ref) values (t2.id, t2.ref);
Is that correct?
This is my query
SELECT PageVisit_ID,TargetSite_ID FROM [A].Datawarehouse.mi.ctb_PageEvent WITH (NOLOCK)
EXCEPT
SELECT PageVisit_ID ,TargetSite_ID FROM [B].Datawarehouse.mi.ctb_PageEvent WITH (NOLOCK)
these two tables from two servers. I need to update targetsite_id in [A].Datawarehouse.mi.ctb_PageEvent records from [B].Datawarehouse.mi.ctb_PageEvent
only matched with above query results.
Try this
DECLARE #SummaryOfChanges TABLE(Change VARCHAR(20));
MERGE INTO [A].Datawarehouse.mi.ctb_PageEvent AS Target
USING ( SELECT PageVisit_ID ,TargetSite_ID FROM [B].Datawarehouse.mi.ctb_PageEvent WITH (NOLOCK)) AS SOURCE
ON Target.TargetSite_ID = Source.TargetSite_ID
WHEN MATCHED THEN
//UPDATE OR do nothing
WHEN NOT MATCHED BY TARGET THEN
//INSERT
OUTPUT $action INTO #SummaryOfChanges;
Please refer to SQL SERVER – Merge Operations – Insert, Update, Delete in Single Execution. my solution just gives a basic idea on how to do this. It might not work 100% initially. Just tweak it once you understand the logic
We have a status table. When the status changes we currently delete the old record and insert a new.
We are wondering if it would be faster to do a select to check if it exists followed by an insert or update.
Although similar to the following question, it is not the same, since we are changing individual records and the other question was doing a total table refresh.
DELETE, INSERT vs UPDATE || INSERT
Since you're talking SQL Server 2008, have you considered MERGE? It's a single statement that allows you to do an update or insert:
create table T1 (
ID int not null,
Val1 varchar(10) not null
)
go
insert into T1 (ID,Val1)
select 1,'abc'
go
merge into T1
using (select 1 as ID,'def' as Val1) upd on T1.ID = upd.ID --<-- These identify the row you want to update/insert and the new value you want to set. They could be #parameters
when matched then update set Val1 = upd.Val1
when not matched then insert (ID,Val1) values (upd.ID,upd.Val1);
What about INSERT ... ON DUPLICATE KEY? First doing a select to check if a record exists and checking in your program the result of that creates a race condition. That might not be important in your case if there is only a single instance of the program however.
INSERT INTO users (username, email) VALUES ('Jo', 'jo#email.com')
ON DUPLICATE KEY UPDATE email = 'jo#email.com'
You can use ##ROWCOUNT and perform UPDATE. If it was 0 rows affected - then perform INSERT after, nothing otherwise.
Your suggestion would mean always two instructions for each status change. The usual way is to do an UPDATE and then check if the operation changed any rows (Most databases have a variable like ROWCOUNT which should be greater than 0 if something changed). If it didn't, do an INSERT.
Search for UPSERT for find patterns for your specific DBMS
Personally, I think the UPDATE method is the best. Instead of doing a SELECT first to check if a record already exists, you can first attempt an UPDATE but if no rows are affected (using ##ROWCOUNT) you can do an INSERT.
The reason for this is that sooner or later you might want to track status changes, and the best way to do this would be to keep an audit trail of all changes using a trigger on the status table.