Strangely, it seems that the EXISTS clause is not supported by DBISAM's sql engine, as it's always resulting in an SQL error. The following is a sample where EXISTS is being used. Am i missing anything here?
update Table1 set HASXACTION = False
WHERE EXISTS (SELECT SERIALID
From Table2
LEFT JOIN Table1 ON (Table2 .AUXILACT = Table1 .CODE)
AND (Table2 .CHARTACT = Table1 .CHARTACT) )
Never mind people, i just learned that DBISAM does not support EXISTS operator for specifying sub-select predicates in WHERE clauses. It's documented within DBISAM's help file(screenshot attached).
I presume that you don't really want the join in the subquery. You probably intend a correlated subquery:
UPDATE Table1
SET HASXACTION = False
WHERE EXISTS (SELECT SERIALID
FROM Table2
WHERE Table2.AUXILACT = Table1.CODE AND Table2.CHARTACT = Table1.CHARTACT
);
This should also fix the problem you are having, which is the reference to Table1 both in the update clause and the subquery. (This is a MySQL limitation.)
EDIT:
I cannot find any reference to EXISTS (or even subqueries) for dbisam. But, you can do updates with joins, so this should be equivalent:
UPDATE Table1
SET HASXACTION = False
FROM Table1 JOIN
Table2
ON Table2.AUXILACT = Table1.CODE AND Table2.CHARTACT = Table1.CHARTACT;
As you've already found, you can do it with the IN. However, there is a limitation that IN can only work with one field. So you can get around it by concatenating two fields to make expressions that fit the criteria. One for the inner, and one for the outer.
update Table1 set HASXACTION = False
WHERE Code+'.'+CHARTACT IN
(
SELECT AUXILACT+'.'+CHARTACT From Table2
)
Related
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
I have a scenario where I would like to update multiple fields in multiple Tables using just one instuction. I need a Syntax to perform such opperations on multiple Databases (Oracle and MSSQL).
At the moment I am stuck at the following statement from MSSQL:
update table1
set table1.value = 'foo'
from table1 t1 join table2 t2 on t1.id = t2.tab1_id
where t1.id = 1234
I would like to update a field in t2 aswell in the same statement.
Further I would like to perform the same Update(s) on Oracle.
EDIT:Seems like I can not update multiple Tables in just one statement. Is there a syntax that works for Oracle and MSSql when updating using a Join?
Regards
Seems like I can not update multiple
Tables in just one statement.
Is there a syntax that works for
Oracle and MSSql when updating using a
Join?
I assume when you re-posed the question you want syntax that will work on both Oracle and SQL Server even though it will inevitably affect only one table.
Entry level SQL-92 Standard code is supported by both platforms, therefore the following 'scalar subqueries' SQL-92 code should work:
UPDATE table1
SET my_value = (
SELECT t2.tab1_id
FROM table2 AS t2
WHERE t2.tab1_id = table1.id
)
WHERE id = 1234
AND EXISTS (
SELECT *
FROM table2 AS t2
WHERE t2.tab1_id = table1.id
);
Note that while using the correlation name t1 for Ttble1 is valid syntax according to the SQL-92 Standard this will materialize a table and the UPDATE will then target the materialized table 't1' and leave your base table 'table1` unaffected, which I assume is not the desired affect. While I'm fairly sure both Oracle and SQL Server are non-compliant is this regard and that in practise would work as expected, there's no harm in being ultra cautious and sticking to the SQL-92 syntax by fully qualifying the target table.
Folk tend not to like the 'repeated' code in the above subqueries (even though the optimizer should be smart enough to evaluate it only once).
More recent versions of Oracle and SQL Server support both support Standard SQL:2003 MERGE syntax, would may be able to use something close to this:
MERGE INTO table1
USING (
SELECT t2.tab1_id
FROM table2 AS t2
) AS source
ON id = source.tab1_id
AND id = 1234
WHEN MATCHED THEN
UPDATE
SET my_value = source.tab1_id;
I just noticed your example is even simpler than I first thought and merely requires a simple subquery that should run on most SQL products e.g.
UPDATE table1
SET my_value = 'foo'
WHERE EXISTS (
SELECT *
FROM table2 AS t2
WHERE t2.tab1_id = table1.id
);
on Oracle, you can update only one table , but you could think of using a trigger .
I've got an Access application with an update query with the following syntax:
UPDATE TABLE1, TABLE2 SET
TABLE2.VALUE1 = TABLE1.VALUE1,
TABLE2.VALUE2 = TABLE1.VALUE2,
TABLE2.VALUE3 = TABLE1.VALUE3,
TABLE2.VALUE4 = TABLE1.VALUE4
The query is working but I do not understand what's going on here.
I'm trying to convert this query to SQL Server.
Can somebody please explain what this query does? My guess is that it's a special Access syntax.
Thanks,
Sven
It uses the older implicit JOIN syntax, although SQL Server should understand that syntax too.
It's INNER JOINing table1 and table2, then moving the values from table1 to table2. Because of the lack of JOIN conditions, if table1 has more than 1 row it may have unpredictable results.
Essentially it is:
UPDATE Table1 INNER JOIN Table2 <<ON Missing Conditions Here>>
SET Table2.Value1 = Table1.Value1
Table2.Value2 = Table1.Value2
Table2.Value3 = Table1.Value3
Table2.Value4 = Table1.Value4
You can convert this to SQL Server with something like this:
UPDATE Table2
SET Table2.Value1 = Table1.Value1
Table2.Value2 = Table1.Value2
Table2.Value3 = Table1.Value3
Table2.Value4 = Table1.Value4
FROM Table1 INNER JOIN Table2 <<ON Missing Conditions Here>>
Every field from TABLE2 will override corresponded field from TABLE1 with records from TABLE1 one by one. Result will be TABLE2 with all replaced records by last row from TABLE1. If TABLE1 has no records - no changes happens.
Sorry for my english.
And... it is SQL.
Try to avoid the "UPDATE with join" syntax in SQL Server. It is completely non-standard SQL but more seriously it gives unpredictable results without any error or warning if the joining criteria is not correct. Use the MERGE statement instead or use the standard version of the UPDATE statement (with a subquery) if you can.