I am just wondering if use = sign operator with sub-query instead of IN
Is it correct way ? and meet the oracle standard ?
Example
select column_name from my_table_1 where id = (select max(id) from my_table_2);
The Difference is related to the number of rows returned. If you have only one row returned from nested sql you may prefer both = or in operators. But if multiple rows returned from nested query, use in operator.
So, in your sql example you may prefer using any of the operators. Since, max functions returns only one row.
As you are fetching maximum value from subquery to compare with id, Both(= and IN )will work fine. But If you are trying to fetch more than one row then you have to use IN keyword.
If you have 1 result in sub query you are fine with using = sign, except when data type is wrong, for example , checking with same data type of dummy VARCHAR2(1)
select * from dual where 'X' = (select max(dual.dummy) from dual);
Is similar to using in (also same explain plain)
select * from dual where 'X' in (select max(dual.dummy) from dual);
But checking with different/wrong data type will result with exception ORA-01722 Invalid number
select * from dual where 1 =(select max(dual.dummy) from dual);
Related
I want to retrieve users name and there responsibility_key where there end_date is null and i want to convert it to (sysdate+1) using nvl but i am only able to retrieve the responsibility_key not the name please help.
The error in the image says "column ambiguously defined". Take a close look. Your last END_DATE could refer to either the u alias or the table from the subquery. Change it to match the rest of your subquery (FIND_USER_GROUPS_DIRECT.END_DATE)
EDIT
Your query is
select u.USER_NAME, d.responsibility_key from FND_USER u,FND_RESPONSIBILITY_VL d
where responsibility_id in(
select responsibility_id from
FND_USER_RESP_GROUPS_DIRECT WHERE END_USER_RESP_GROUPS_DIRECT.END_DATE=nvl(END_DATE,sysdate+1)) and
u.END_DATE=nvl(END_DATE,SYSDATE + 1)
;
The query isn't formatted, which makes it hard to read.
Not all columns are qualified with table name (or aliases), as mentioned in the comments.
The query currently uses an implicit join.
The query is impossible to understand without seeing the table definitions (desc [table_name]).
For points 1 and 2, a properly formatted query will look something like
select u.user_name, d.responsibility_key
from
fnd_user u,
fnd_responsibility_vl d
where
d.responsibility_id in (
select urgd.responsibility_id
from
fnd_user_resp_groups_direct urgd
where
urgd.end_date = nvl(u.end_date, sysdate+1)
) and
u.end_date = nvl(urgd.end_date, sysdate + 1)
;
This makes it easier to read and in addition to this, you can see that without table definitions I guessed (see point 4) as to which tables the end_date column belongs in your query. If I had to guess, so does Oracle. That means you have an ambiguity problem. To fix it, take a close look at the end_date column as it appears in your original query and where you do not prefix it with anything, you need to prefix it with the appropriate alias (after you have aliased all your tables).
For point 3, you can write your query more clearly with an explicit join and by using aliases for all columns. As for the explicit join I have no idea what your tables look like but one possibility is something like
select u.user_name, d.responsibility_key
from fnd_user u
join fnd_responsibility_vl d
on u.id = d.user_id
where
d.responsibility_id in (
select responsibility_id
from fnd_user_resp_groups_direct urgd
where
urgd.end_date = nvl(u.end_date, sysdate+1)
) and
u.end_date = nvl(urgd.end_date, sysdate+1)
;
If you follow these points you will get to the root of the error.
How do I return data out of IF statements? I have a IF statement which is meant to return a different result dependent of the result of that statement.
IF :Value = 1 THEN
SELECT Name FROM TABLE_A
ELSEIF :Value = 2 THEN
SELECT Name FROM TABLE_B
ELSEIF :Value = 3 THEN
SELECT Name FROM TABLE_C
but this doesn't work. It expects an INTO statement in those selects. I suspect this is because Oracle can't return out of a block?
Is there a quicker way to return those select statements without creating table variables to store the data or messing around with functions?
You can do this by plain SQL:
SELECT
':Value' user_input,
CASE
WHEN ':Value' IN('a1','a2','a3')
THEN (select name from table_a)
WHEN ':Value' = 'i'
THEN (select name from table_b)
END AS output
FROM
dual
(good info about case)
If you want more than one result in your cases, then you may opt to an intelligent UNION:
SELECT t1_Col_1, t1_Col_2,'&VALUE' from TABLE_1
WHERE '&VALUE' = '1'
UNION ALL
SELECT t2_Col_1, t2_Col_2,'&VALUE' from TABLE_2
WHERE '&VALUE' = '2'
In this solution, types and number of tx_Coln must be the same.
I'm facing a problem in Oracle.
I had a SQL where some values were fixed. Now I started replacing them with values from a parameter-table. Some of these fixed values where in a NVL().
Simply said my statement is like this.
SELECT NVL(MAX(t.datefield), to_date('01011900','DDMMYYYY'))
FROM table t;
That works fine.
Now I want to replace the fixed date to a date from my parameter-table with a subselect, which doesn't work at all.
// Works
SELECT NVL(MAX(NULL), 'hello') FROM DUAL;
// Doesn't work
SELECT NVL(MAX(NULL), (SELECT 'hello' FROM DUAL)) FROM DUAL;
The error is:
ORA-00937: .... "not a single-group group function"
I have no idea how to group by a subselect.
Any help is very appreciated! Thanks!
You can't group by a sub-select. However, in order to achieve this your sub-select is only going to be able to return one row. So, change it into a Cartesian join and group by that.
SELECT NVL(MAX(NULL), str)
FROM DUAL
CROSS JOIN ( SELECT 'hello' as str FROM DUAL )
GROUP BY STR
More generally every column that is not included in an aggregate function must be included in the GROUP BY. Plus NVL() is bad; use COALESCE() or CASE instead.
hi guy i have a query that give me the followin error:
ORA-01791: not a SELECTed expression
this is the select expresison , please can you tell me why ?
declare
freqLettura varchar2(64);
billingcy varchar2(64);
begin
freqLettura := null;
billingcy := null;
for rec in ( select distinct(fn_get_facilityid(z.uidfacility) ) as a, 1 as b
from facilityhistory z,
locality l ,
plant p ,
ztmp_sam_tb_sdv zsdv ,
ztmp_sam_tb_plantcode zplant ,
sam_tb_ca_pdr sam,
meterhistory mh,
meter m ,
meterclass mc
where
Z.UIDLOCALITY = L.UIDLOCALITY and
p.UIDPLANT = L.UIDPLANT and
z.uidaccount = zsdv.uidaccount and
p.plantcode = zplant.plantcode and
sam.uidfacility = z.uidfacility and
z.stoptime is null and
sam.status = 'U' and
mh.uidfacility = z.uidfacility and
mh.uidmeter = m.uidmeter and
m.uidmeterclass = mc.uidmeterclass and
(billingcy is null or p.UIDBILLINGCYCLE = billingcy )
AND
(
(
(freqLettura = 'G') AND ( mh.corrmeterid is not null and mh.stoptime is null and mc.maxflowmeter >= SAM_FN_GET_PARAMETER_FLOAT('MAXFLOWMET_DETT_GIORN'))
)
OR
(
nvl(freqLettura,'nullo') <> 'G' AND (freqLettura is null or sam.readfrequency = freqLettura)
)
) and ROWNUM = 1 order by sam.stoptime, sam.uidsamtbpdr desc ) loop
begin
insert into ztmp_sam_tb_elab_pdr (facilityid, uidbatchrequest) VALUES (rec.a, rec.b);
exception
when dup_val_on_index then
null;
end;
end loop;
end;
Whenever you get an Oracle error message you don't understand, the first thing to do is look up the meaning. One way is simply to Google it. In this case the full description found in
Oracle9i Database Error Messages is:
ORA-01791 not a SELECTed expression
Cause: There is an incorrect ORDER
BY item. The query is a SELECT DISTINCT query with an ORDER BY clause.
In this context, all ORDER BY items must be constants, SELECT list
expressions, or expressions whose operands are constants or SELECT
list expressions.
Action: Remove the inappropriate ORDER BY item from the SELECT list
and retry the statement.
(Oddly this error message isn't documented in the 10G or 11G manuals, despite still being raised!)
This matches the statement you have written, which is a SELECT DISTINCT query where you are trying to order the results by a column that you did not select.
If you think about it, what you are asking for doesn't make sense: by selecting DISTINCT values that do not include sam.stoptime (for example) you may be consolidating many rows with different values for sam.stoptime, so which one would govern the ordering?
Also, as Noel's answer points out, there is no reason to have an ORDER BY clause in this code anyway, so the solution is simply to remove it.
If you are using DISTINCT in your SELECT query, then your ORDER BY clause should contain only those columns that your selecting. In this case sam.stoptime, sam.uidsamtbpdr are not there in SELECT statement. You can remove the ORDER BY clause, as it is not doing anything useful in your example.
I'm having a small issue with sorting the data returned from a query, with the aim of getting the oldest updated value in dataset so that I can update only that record. Here's what I'm doing:
WHERE ROWNUM = 1 AND TABLE1.ID != V_IGNOREID
AND TABLE1.LASTREADTIME = (SELECT MIN(TABLE1.LASTREADTIME) FROM TABLE1)
ORDER BY TABLE1.LASTREADTIME DESC;
It makes no difference as to whether the ORDER BY statement is included or not. If I only use the ROWNUM and equality checks, I get data, but it alternates between only two rows, which is why I'm trying to use the LASTREADTIME data (so that I can modify more than these two rows). Anybody have any thoughts on this, or any suggestions as to how I can use the MIN function effectively?
Cheers
select * from (
-- your original select without rownum and with order by
)
WHERE ROWNUM = 1
EDIT some explanation
I think the order by clause is applied on the resultset after the where clause. So if the rownum = 1 is in the same select statement with the order by, then it will be applied first and the order by will order only 1 row, which will be the first row of the unordered resultset.