I have a select statement that is showing me all the data from table original every time it does not match the values on table real_values.
So every time it does not match, instead of showing me which routes have the wrong values for capacity, I would like the query to update it with the correct values.
Here is a shorter version to use as an example:
http://sqlfiddle.com/#!4/6a904/1
Instead of being a select statement, how could I just update the values? I have tried some things I've seen online but nothing seems to work.
#DavidFaber's answer is how most people would do this. However, for this kind of query, I prefer to use merge over update:
MERGE INTO original o
USING real_values rv
ON (o.origin = rv.origin AND o.destination = rv.destination)
WHEN MATCHED THEN
UPDATE SET
o.capacity_wt = rv.capacity_wt, o.capacity_vol = rv.capacity_vol
WHERE o.capacity_wt != rv.capacity_wt
OR o.capacity_vol != rv.capacity_vol
(It was unclear to me from your question whether you want to update original or real_values, so I chose one. If I got this wrong, reversing it should be trivial.)
I find merge more readable and easier to use when you want to update multiple columns.
The usual form of such an update query in Oracle is the following:
UPDATE table1 t1
SET t1.value = ( SELECT t2.value FROM table2 t2
WHERE t2.key = t1.key )
WHERE EXISTS ( SELECT 1 FROM table2 t2
WHERE t2.key = t1.key );
I'm confused though. You've tagged this question oracle and sql-server but your fiddle link uses MySQL.
In SQL Server, you would do this
update original set capacity_wt=b.capacity_wt,capacity_vol=b.capacity_vol
from original a, real_values b
where a.origin = b.origin
and a.destination = b.destination
and (a.capacity_wt != b.capacity_wt
or b.capacity_vol != b.capacity_vol);
Related
I maintain an application developed in Access. And I have to implement an update query, but I'm quite stuck at the moment and I don't understand why.
Basically, the query must update a record from table X following another record from that same table, but the query I wrote does nothing, I did test separately the update and the select and they both work, but together, no.
I hope some of you may found my problem.
Here is the query I wrote (I did remove some fields to avoid to be too long, and of course, the query you will see was tested to be sure it was not the missing fields the issue)
UPDATE
TABLE_X AS recordToUpdate,
(
SELECT
DUP_C2B_From_CPL.[NUM-GrpHdr],
DUP_C2B_From_CPL.[NUM-LOT],
DUP_C2B_From_CPL.[SINGLE-SCENARIO],
DUP_C2B_From_CPL.EqvtAmt,
DUP_C2B_From_CPL.EqvtAmtCur,
DUP_C2B_From_CPL.EqvtAmtCurTft,
DUP_C2B_From_CPL.XchgRateInfExchangeRate,
DUP_C2B_From_CPL.XchgRateInfRateType,
DUP_C2B_From_CPL.XchgRateInfContractId,
DUP_C2B_From_CPL.ChqTp
FROM DUP_C2B_From_CPL
) AS originalRecord
SET
recordToUpdate.EqvtAmt = originalRecord.EqvtAmt,
recordToUpdate.EqvtAmtCur = originalRecord.EqvtAmtCur,
recordToUpdate.EqvtAmtCurTft = originalRecord.EqvtAmtCurTft,
recordToUpdate.XchgRateInfExchangeRate = originalRecord.XchgRateInfExchangeRate,
recordToUpdate.XchgRateInfRateType = originalRecord.XchgRateInfRateType,
recordToUpdate.XchgRateInfContractId = originalRecord.XchgRateInfContractId,
recordToUpdate.ChqTp = originalRecord.ChqTp
WHERE
recordToUpdate.[SINGLE-SCENARIO] = 112811
DUP_C2B_From_CPL here is a subQuery that is retrieving the record I'm interested in so I can take its values to update the other one.
In the last WHERE closure, I hardcoded the id for more readability for you (and yes it exists :))
And also the designer is rendering correctly, so no error on this side. But as I said, it seems that it is not updating anything.
Don't hesitate to tell me if you nee more information.
You can try something like below.
UPDATE
Table1 AS t1
INNER JOIN Table1 AS t2
ON t1.Field1 = t2.Field2
SET
T1.Field1 = t2.field1
If there is not any join then you can try like below
UPDATE Table1 t1 , Table1 t2
SET T1.Field1 = t2.field1
where t1.field1 = 'aa' and t2.field1 = 'bb'
Well, for some reason, I had to restart my laptop, and the query is now working.
Thank you for your help.
As title says, I was wondering how I can calculate and set a variable inside a merge statement. If that is even possible.
Example:
MERGE TABLE_1 as target
USING TABLE_2 as source
ON (target.USER_ID = source.USER_ID)
WHEN NOT MATCHED THEN
INSERT (
USER_ID,
CURRENT_CALCULATION,
CURRENT_CALCULATION_VALUE )
VALUES (
source.USER_ID,
SET #CURRENT_CALCULATION = (select value from table3 where table3.USER_ID = source.USER_ID),
... REUSE #CURRENT_CALCULATION for other purposes ...
);
I have tried different kind of syntax but none seems to work.
I don't believe this is possible. Without a little more detail I can't be sure that this will work for your situation, but how about simply carrying out this logic before your MERGE statement? You could always dump everything into a temp table at the point you do all the calculations if what you're trying to avoid is hitting the same tables twice.
If you did that, you could simply use your temp table as the source for the merge - you may not even need to put it into a variable, as you might be able to include it as a column of the temp table.
Move the logic to source part of Merge and reuse it
MERGE TABLE_1 AS target
USING (SELECT t2.*,
t3.value
FROM TABLE_2 t2
LEFT JOIN table3 t3
ON t3.USER_ID = t2.USER_ID) AS source
ON ( target.USER_ID = source.USER_ID )
WHEN NOT MATCHED THEN
INSERT ( USER_ID,
CURRENT_CALCULATION,
CURRENT_CALCULATION_VALUE )
VALUES ( source.USER_ID,
source.value,
source.value + some logic );
Considering there is 1:1 relationship between table 2 and table 3 based on your correlated sub-query used to find #CURRENT_CALCULATION
I am having difficulties getting my second alias to work in the example below.
I'm using Squirrel SQL 3.7
Getting an error
Error: [SQL5001] Column qualifier or table T2 undefined. SQLState:
42703 ErrorCode: -5001
UPDATE myDatabaseOne.myTableOne t1
SET
firstFieldToCopy = (SELECT DISTINCT alternateField FROM myDatabaseTwo.myTableTwo t2)
WHERE t1.firstFieldToCopy = t2.alternateField;
Did you mean...
UPDATE myDatabaseOne.myTableOne t1
SET firstFieldToCopy = (SELECT DISTINCT alternateField
FROM myDatabaseTwo.myTableTwo t2
WHERE t1.firstFieldToCopy = t2.alternateField);
Note the position of the ) ... This is why the t2 alias didn't work...
Otherwise the query is confusing as to your intent.
UPDATE t1
SET t1.firstfieldtocopy = t2.alternatefield
FROM mydatabaseone.mytableone t1
JOIN mydatabasetwo.mytabletwo t2 on t1.firstfieldtocopy = t2.alternate field
I don't understand your logic though.. Setting copy = alternate but you're filtering to where copy = alternate already.
The issue is with scoping. t2 is only accessible within
(SELECT DISTINCT alternateField FROM myDatabaseTwo.myTableTwo t2)
which means that when you say WHERE t1.firstFieldToCopy = t2.alternateField your DBMS has no clues what you're referring to.
There are still 2 issues to the query though :
Your subquery most probably returns 2+ values since DISTINCT isn't used to return a single value, but to eliminate duplicates.
You're overriding old values with identical new values (see Aaron D's answer).
I have an update query for an Oracle SQL db. Upon execution the query returns ORA-00904: "t1"."sv_id": invalid identifier
So, why do I get an "invalid identifier" error message although the column exists?
Here is the complete query (replaced actual table and column names by dummies in np++)
UPDATE table_1 t1 SET (type) =
CASE
WHEN
((SELECT COUNT(dateCheck.id) FROM table_2 dateCheck
WHERE dateCheck.s_id = t1.s_id AND dateCheck.sv_id = t1.sv_id) = 0)
THEN
(SELECT sv.type FROM table_3 sv WHERE sv.id = t1.sv_id)
ELSE
(SELECT type FROM
(SELECT d.type as type FROM table_2 d
WHERE d.s_id = t1.s_id AND d.sv_id = t1.sv_id
ORDER BY d.creationTimestamp ASC)
WHERE ROWNUM = 1)
END
Now I don't understand why that error occurs.
Here is what I already know:
The Queries in the CASE statement work when executed separately, provided they are wrapped into a query that provides table_1 t1 for sure.
t1.s_id seems to work since oracle doesn't complain about that. When i change it to a column that really doesn't exist, oracle starts complaining about that non existent column before returning something about t1.sv_id. So somehow the alias might work, although I'm not sure about it.
I'm 100% sure that the column t1.sv_id exists and no typo was made. Executed a query on t1 directly and doublechecked everything in notepad by marking all occurences.
An (completely unrelated) update query like the following works as well (note the alias t1 is used in the select query). Don't assume table_1/2 to be the same as in the update query above, just reused the names. This should just illustrate that I successfully used an alias in an update query before.
update table_1 t1 set (t2_id) = (select id from table_2 t2 where t1.id = t2.t1_id)
UPDATE
Thx a lot for pointing me to the "you don't have access to alises in deeper suquery layers" issue. That got me on track again pretty fast.
So here is the query I ended up with. This seems to work fine. Eliminates the acces to t1 in the deeper layers and selects the oldest row, so that the same result should be returned from the query I expected from the original query in the ELSE part.
UPDATE table_1 t1 SET (type) =
CASE
WHEN
((SELECT COUNT(dateCheck.id) FROM table_2 dateCheck
WHERE dateCheck.s_id = t1.s_id AND dateCheck.sv_id = t1.sv_id) = 0)
THEN
(SELECT sv.type FROM table_3 sv WHERE sv.id = t1.sv_id)
ELSE
(SELECT d.type as type FROM table_2 d
WHERE d.s_id = t1.s_id
AND d.sv_id = t1.sv_id
AND d.creation = (SELECT MIN(id.creation) FROM table_2 id
WHERE d.s_id = id.s_id AND d.sv_id = id.sv_id))
END
You can't reference a table alias in a subquery of a subquery; the alias doesn't apply (or doesn't exist, or isn't in scope, depending on how you prefer to look at it). With the code you posted the error is reported against line 11 character 24, which is:
(SELECT type FROM
(SELECT d.type as type FROM table_2 d
WHERE d.s_id = t1.s_id AND d.sv_id = t1.sv_id
^^^^^^^^
If you change the t1.s_id reference on the same line to something invalid then the error doesn't change and is still reported as ORA-00904: "T1"."SV_ID": invalid identifier. But if you change the same reference on line 5 instead to something like
((SELECT COUNT(dateCheck.id) FROM table_2 dateCheck
WHERE dateCheck.s_id = t1.s_idXXX AND dateCheck.sv_id = t1.sv_id) = 0)
... then the error changes to ORA-00904: "T1"."S_IDXXX": invalid identifier. This is down to how the statement is being parsed. In your original version the subquery in the WHEN clause is value, and you only break it by changing that identifier. The subquery in the ELSE is also OK. But the nested subquery in the ELSE has the problem, and changing the t1.s_id in that doesn't make any difference because the parser reads that part of the statement backwards (I don't know, or can't remember, why!).
So you have to eliminate the nested subquery. A general approach would be to make the whole CASE an inline view which you can then join using s_id and sv_id, but that's complicated as there may be no matching table_2 record (based on your count); and there may be no s_id value to match against as that isn't being checked in table_3.
It isn't clear if there will always be a table_3 record even then there is a table_2 record, or if they're mutually exclusive. If I've understood what the CASE is doing then I think you can use an outer join between those two tables and compare the combined data with the row you're updating, but because of that ambiguity it needs to be a full outer join. I think.
Here's a stab at using that construct with a MERGE instead of an update.
MERGE INTO table_1 t1
USING (
SELECT t2.s_id,
coalesce(t2.sv_id, t3.id) as sv_id,
coalesce(t2.type, t3.type) as type,
row_number() over (partition by t2.s_id, t2.sv_id
order by t2.creationtimestamp) as rn
FROM table_2 t2
FULL OUTER JOIN table_3 t3
ON t3.id = t2.sv_id
) tmp
ON ((tmp.s_id is null OR tmp.s_id = t1.s_id) AND tmp.sv_id = t1.sv_id AND tmp.rn = 1)
WHEN MATCHED THEN UPDATE SET t1.type = tmp.type;
If there will always be a table_3 record then you could use that as the driver and have a left outer join to table_2 instead, but hard to tell which might be appropriate. So this is really just a starting point.
SQL Fiddle with some made-up data that I believe would have hit both branches of your case. More realistic data would expose the flaws and misunderstandings, and suggest a more robust (or just more correct) approach...
Your query and your analysis seems sound to me. I have no solution but a few things you can try to maybe trigger something that explains this odd behavior:
Quote the column (just in case it happens to be a SQL keyword).
Use table_1.sv_id - this works as long as the whole query contains this table only once.
Make sure that the alias t1 exists only once
Run the query with a query tool like SQuirrel SQL - the tool can examine the exact position where Oracle reports the problem. Maybe it's in a different place of the query than you think
Check () and make sure they are around the parts where they should be.
Swap the order of expressions around =
I have a statement that needs writing (with generic names for stuff, since this is for work) to update a column 'updCol' in table 'tUpd'. tUpd also has a column 'linkCol' which is present in another table tOther. tOther has another column 'idCol'.
My problem is to update the updCol value of rows in tUpd which correspond via linkCol to rows with a given idCol value.
One solution I think should work is the following;
update
tUpd
set
updCol = XXX
where exists (
select
idCol
from
tOther
where
tOther.linkCol = tUpd.linkCol
and tOther.idCol = MY_ID
)
However, I have worries that this approach will lead to poor performance, since I've been warned of sub-queries in relation to performance before - this sub-query will be run once for each row of tUpd, is this correct?
Has anyone got a better suggestion?
Important Update: my workplace avoids using SQL JOINs at all costs, preferring to join within the where clauses using, eg, where a.col = b.col. This is arguably rather awkward but allows a flexibility in especially logging which I don't fully understand. SO, I'm looking for non-JOIN-using solutions :)
All the above solutions gives an error in Informix as it cannot find the one of the table.
Here is a solution for this which worked for me:
update table1
set table1.field2 = (select table2.field2 from table2 where table1.field1 = table2.field1)
where table1.field1 in (select table2.field1 from table2)
edit: A multi-column solution from another question
update table1
set (table1.field2, table2.field3) = (
(select table2.field2, table2.field3
from table2
where table1.field1 = table2.field1)
)
where table1.field1 in (select table2.field1 from table2)
Its simply like this
UPDATE DestinationTable
SET DestinationTable.UpdateColumn = SourceTable.UpdateColumn
FROM SourceTable
WHERE DestinationTable.JoinColumn = SourceTable.JoinColumn
Maybe it will help you
update tUpd
set tU.updCol = XXX
from tOther tot, tUpd tU
where tot.linkCol = tU.linkCol
and tot.idCol = MY_ID
Here is link to similar problem.
This works for Informix Databases:
UPDATE dest_table V
SET field_1 =
(SELECT field_1 FROM source_tbl WHERE field_2 IS NULL
AND field_1 = V.field_1);
Reference