I have a fairly intricate query and I am finding it difficult to create the result of updating two different tables from the same subquery in the FROM. The difficulty I am facing is suggesting I have attempted the incorrect flow:
Below is an extremely simplified version of the script I have working for updating table1 from the subquery:
UPDATE
table1
SET
columnX= subquery.column2
FROM
(
SELECT column1, column2, column2
FROM table2
) AS subquery
WHERE subquery.column1 = table1.column1;
Now I need to bring a third table (table3) into the mix and map table2(subquery).column2 to a value on INSERT.
I cannot do this using a second query which would be ideal as the subquery generates UUID's that must persist across the table1.columnX and table3.column1.
Can I include the INSERT within the subquery whilst still returning the same subquery table?
INSERT...RETURNING uuid_column_name may be the magic you need in your subquery.
https://www.postgresql.org/docs/13/sql-insert.html
Related
I am facing this issue, can someone help to validate this merge statement?
MERGE INTO WC_FNHLDNG_D T1
USING (SELECT distinct ROW_WID, CONTACT_WID
FROM W_ASSET_D
WHERE X_TYPE_CD='Fin Account')T2
ON (T1.ASSET_WID=T2.ROW_WID)
WHEN MATCHED THEN UPDATE
SET T1.CONTACT_WID=T2.CONTACT_WID;
Acquire locks on WC_FNHLDNG_D and W_ASSET_D before attempting the MERGE operation.
The rule of merge is that there must be no more than one row in the USING subquery which matches a row in the target table.
Your subquery is this:
SELECT distinct ROW_WID, CONTACT_WID
FROM W_ASSET_D
So if there is more than one different CONTACT_WID for a given ROW_WID it will return multiple rows for the ROW_WID. The DISTINCT clause won't help, because the CONTACT_WID are different.
The fact that your statement hurls ORA-30926 suggests this is the state of your data. Oracle doesn't know which W_ASSET_D.CONTACT_WID is the right one to merge into WC_FNHLDNG_D so it gives up. The solution to rewrite the USING subquery so it returns only one CONTACT_WID per ROW_WID.
You should have some additional business rules you can add in a WHERE clause. But as a last resort you can use an aggregating function, e.g.
USING (SELECT ROW_WID, max( CONTACT_WID) as CONTACT_WID
FROM W_ASSET_D
WHERE X_TYPE_CD='Fin Account'
group by ROW_WID
)T2
This is better than choosing a random CONTACT_WID but not by much :)
I maintain an application where I am trying to optimize an Oracle SQL query wherein multiple IN clauses are used. This query is now a blocker as it hogs nearly 3 minutes of execution time and affects application performance severely.The query is called from Java code(JDBC) and looks like this :
Select disctinct col1,col2,col3,.. colN from Table1
where 1=1 and not(col1 in (idsetone1,idsetone2,... idsetoneN)) or
(col1 in(idsettwo1,idsettwo2,...idsettwoN))....
(col1 in(idsetN1,idsetN2,...idsetNN))
The ID sets are retrieved from a different schema and therefore a JOIN between column1 of table 1 and ID sets is not possible. ID sets have grown over time with use of the application and currently they number more than 10,000 records.
How can I start with optimizing this query ?
I really doupt about "The ID sets are retrieved from a different schema and therefore a JOIN between column1 of table 1 and ID sets is not possible." Of course you can join the tables, provided you got select privileges on it.
Anyway, let's assume it is not possible due to whatever reason. One solution could be to insert all entries first into a Nested Table and the use this one:
CREATE OR REPLACE TYPE NUMBER_TABLE_TYPE AS TABLE OF NUMBER;
Select disctinct col1,col2,col3,.. colN from Table1
where 1=1
and not (col1 NOT MEMBER OF (NUMBER_TABLE_TYPE(idsetone1,idsetone2,... idsetoneN))
OR
(col1 MEMBER OF NUMBER_TABLE_TYPE(idsettwo1,idsettwo2,...idsettwoN))
Regarding the max. number of elements Oracle Documentation says: Because a nested table does not have a declared size, you can put as many elements in the constructor as necessary.
I don't know how serious you can take this statement.
You should put all the items into one temporary table and to an explicit join:
Select your cols
from Table1
left join table_with_items
on table_with_items.id = Table1.col1
where table_with_items.id is null;
Also that distinct suggest a problem in your business logic or in the architecture of application. Why do you have duplicate ids? You should get rid of that distinct.
Let's say we have a query like this (my actual query is similar to this but pretty long)
insert into t1(id1,c1,c2)
select id1,c1,c2 from t2
where not exists(select * from t1 where t1.id1=t2.id1-1)
Does this query select first and insert all, or insert each selected item one by one?
it matters because I'm trying insert a record depending on the previous inserted records and it doesn't seem to work.
First the select query is ran. So it will select all the rows that match your filter. After that the insert is performed. There is not row by row insertion when you use one operation.
Still if you want to do something recursive that will check after each insert you can use CTEs (Common Table Expressions). http://msdn.microsoft.com/en-us/library/ms190766(v=sql.105).aspx
This runs a select statement one time and then inserts based on that. It is much more efficient that way.
Since you already know what you will be inserting, you should be able to handle this in your select query rather than looking at what you have already inserted.
This question already has an answer here:
Access SQL Update One Table In Join Based on Value in Same Table
(1 answer)
Closed 10 years ago.
For the following query:
UPDATE tempSpring_ASN AS t
SET t.RECORD_TYPE = (
SELECT TOP 1 RECORD_TYPE
FROM (
SELECT "A" AS RECORD_TYPE
FROM TABLE5
UNION ALL
SELECT "B" AS RECORD_TYPE
FROM TABLE5
)
);
I'm getting, "Operation must use an updateable query." I don't understand. I'm not trying to update a union query. I'm just trying to update an otherwise updatable recordset with the output (single value) of a union query.
(The solution provided at Access SQL Update One Table In Join Based on Value in Same Table (which is also provided below) does not work for this situation, contrary to what is indicated on the top of this page.)
This question is a reference to a previous question, data and code examples posted here:
Access SQL Update One Table In Join Based on Value in Same Table
Hi AYS,
In Access, an Update query needs to be run on a table.
As a UNION query is a combination of multiple sets of records, the result set is no longer a table, and cannot be the object of an Update query as the records in the result set are no longer uniquely identified with any one particular table (even if they theoretically could be). Access is hard-coded to treat every UNION query as read-only, which makes sense when there are multiple underlying tables. There are a number of other conditions (such as a sub-query in the SELECT statement) that also trigger this condition.
Think if it this way: if you were not using TOP 1 and your UNION query returned multiple results, how would JET know which result to apply to the unique record in your table? As such, JET treats all such cases the same.
Unfortunately, this is the case even when all of the data is being derived from the same table. In this case, it is likely that the JET optimizer is simply not smart enough to realize that this is the case and re-phrase the query in a manner that does not use UNION.
In this case, you can still get what you want by re-stating your query in such a way that everything references your base table. For example, you can use the following as a SELECT query to get the PO_NUM value of the previous SHP_CUSTOM_5 record:
SELECT
t1.SHP_CUSTOM_5
, t1.PO_NUM
, t1.SHP_CUSTOM_5 -1 AS PREV_RECORD
, (SELECT
t2.PO_NUM
FROM
tempSpring_ASN As t2
WHERE
t2.SHP_CUSTOM_5 = (t1.SHP_CUSTOM_5 -1)
) AS PREV_PO
FROM
tempSpring_ASN AS t1
;
You can then phrase this as an Update query as follows in order to perform the "LIN" updates:
UPDATE
tempSpring_ASN AS t1
SET
t1.RECORD_TYPE = "LIN"
WHERE
t1.PO_NUM=
(
SELECT
t2.PO_NUM
FROM
tempSpring_ASN As t2
WHERE
t2.SHP_CUSTOM_5 = (t1.SHP_CUSTOM_5 -1)
)
;
This code was successful in the tests I ran with dummy data.
Regarding your "HDR" updates, your are really performing two separate updates.
1) If the PO_NUM matches the previous record's PO_NUM, set RECORD_TYPE to "LIN"
2) If it is the first record, set RECORD_TYPE to "HDR"
It is not clear to me why there would be a benefit to performing these actions within one query. I would recommend performing the HDR update using the "TOP 1" by SHP_CUSTOM_5 method you used in your original SELECT query example, as this will be a relatively simple UPDATE query. It is possible to use IIF() within an Update query, but I do not know what additional benefit you would gain from the additional time and complexity that would be required (it would most likely only be much less readable).
Best of luck!
I have two different tables with similar schema in different database. What is the best way to compare records between these two tables. I need to find out-
records that exists in first table whose corresponding record does not exist in second table filtering records from the first table with some where clauses.
So far I have come with this SQL construct:
Select t1_col1, t1_ col2 from table1
where t1_col1=<condition> AND
t1_col2=<> AND
NOT EXISTS
(SELECT * FROM
table2
WHERE
t1_col1=t2_col1 AND
t1_col2=t2_col2)
Is there a better way to do this?
This above query seems fine but I suspect it is doing row by row comparison without evaluating the conditions in the first part of the query because the first part of the query will reduce the resultset very much. Is this happening?
Just use except keyword!!!
Select t1_col1, t1_ col2 from table1
where t1_col1=<condition> AND
t1_col2=<condition>
except
SELECT t2_col1, t2_ col2 FROM table2
It returns any distinct values from the query to the left of the EXCEPT operand that are not also returned from the right query.
For more information on MSDN
If the data in both table are expected to have the same primary key, you can use IN keyword to filter those are not found in the other table. This could be the simplest way.
If you are open to third party tools like Redgate Data Compare you can try it, it's a very nice tool. Visual Studio 2010 Ultimate edition also have this feature.