I am trying to get a list of locks on ORACLE. When there are no locks, an empty string is returned. How to make it output 0 if there are no rows, and output the required result if there are rows?
SELECT (b.seconds_in_wait) as TIME
FROM sys.v_$session b, sys.dba_blockers c, sys.dba_lock a
WHERE c.holding_session = a.session_id AND c.holding_session = b.sid and (username like '%MOBILE%');
I don't even know where to look for the answer)
Left join your sql to a dummy row and handle null with Nvl() function
WITH
dummy AS
( Select 0 "DUMMY" From Dual),
blocked AS
( -- your SQL using Joins
SELECT b.SECONDS_IN_WAIT "A_TIME"
FROM sys.v_$session b
INNER JOIN sys.dba_lock a ON(a.SESSION_ID = b.SID)
INNER JOIN sys.dba_blockers c ON(c.HOLDING_SESSION = b.SID)
WHERE b.username LIKE('%MOBILE%')
)
SELECT Nvl(b.A_TIME, 0) "A_TIME"
FROM dummy
LEFT JOIN blocked b ON(1 = 1)
Use the below by creating a virtual row using DUAL
WITH SUB_QUERY AS(
SELECT (b.seconds_in_wait) as TIME
FROM sys.v_$session b, sys.dba_blockers c, sys.dba_lock a
WHERE c.holding_session = a.session_id AND c.holding_session = b.sid
and(username like '%MOBILE%'))
select * FROM SUB_QUERY
union all
select 0 FROM DUAL
where NOT EXISTS (SELECT 1 FROM SUB_QUERY);
I would simply query the dual table and outer join the wait time query to it, like so:
WITH wait_time AS
(SELECT (b.seconds_in_wait) AS TIME
FROM sys.v_$session b,
sys.dba_blockers c,
sys.dba_lock a
WHERE c.holding_session = a.session_id
AND c.holding_session = b.sid
AND (username LIKE '%MOBILE%'))
SELECT NVL(wt.time, 0)
FROM dual
LEFT OUTER JOIN wait_time wt ON 1=1;
That way, you'll always get at least one row returned, and you're only querying the wait time query once.
Related
Regarding the statement below, sltrxid can exist as both ardoccrid and ardocdbid. I'm wanting to know how to include both in the NOT IN subquery.
SELECT *
FROM glsltransaction A
INNER JOIN cocustomer B ON A.acctid = B.customerid
WHERE sltrxstate = 4
AND araccttype = 1
AND sltrxid NOT IN(
SELECT ardoccrid,ardocdbid
FROM arapplyitem)
I would recommend not exists:
SELECT *
FROM glsltransaction t
INNER JOIN cocustomer c ON c.customerid = t.acctid
WHERE
??.sltrxstate = 4
AND ??.araccttype = 1
AND NOT EXISTS (
SELECT 1
FROM arapplyitem a
WHERE ??.sltrxid IN (a.ardoccrid, a.ardocdbid)
)
Note that I changed the table aliases to things that are more meaningful. I would strongly recommend prefixing the column names with the table they belong to, so the query is unambiguous - in absence of any indication, I represented this as ?? in the query.
IN sometimes optimize poorly. There are situations where two subqueries are more efficient:
SELECT *
FROM glsltransaction t
INNER JOIN cocustomer c ON c.customerid = t.acctid
WHERE
??.sltrxstate = 4
AND ??.araccttype = 1
AND NOT EXISTS (
SELECT 1
FROM arapplyitem a
WHERE ??.sltrxid = a.ardoccrid
)
AND NOT EXISTS (
SELECT 1
FROM arapplyitem a
WHERE ??.sltrxid = a.ardocdbid
)
I have a question on sql desgin.
Context:
I have a table called t_master and 13 other tables (lets call them a,b,c... for simplicity) where it needs to compared.
Logic:
t_master will be compared to table 'a' where t_master.gen_val =
a.value.
If record exist in t_master, retrieve t_master record, else retrieve 'a' record.
I do not need to retrieve the records if it exists in both tables (t_master and a) - XOR condition
Repeat this comparison with the remaining 12 tables.
I have some idea on doing this, using WITH to subquery the non-master tables (a,b,c...) first with their respective WHERE clause.
Then use XOR statement to retrieve the records.
Something like
WITH a AS (SELECT ...),
b AS (SELECT ...)
SELECT field1,field2...
FROM t_master FULL OUTER JOIN a FULL OUTER JOIN b FULL OUTER JOIN c...
ON t_master.gen_value = a.value
WHERE ((field1 = x OR field2 = y ) AND NOT (field1 = x AND field2 = y))
AND ....
.
.
.
.
Seeing that I have 13 tables that I need to full outer join, is there a better way/design to handle this?
Otherwise I would have at least 2*13 lines of WHERE clause which I'm not sure if that will have impact on the performance as t_master is sort of a log table.
**Assume I cant change any schema.
Currently I'm not sure if this SQL will working correctly yet, so I'm hoping someone can guide me in the right direction regarding this.
update from used_by_already's suggestion:
This is what I'm trying to do (comparison between 2 tables first, before I add more, but I am unable to get values from ATP_R.TBL_HI_HDR HI_HDR as it is in the NOT EXISTS subquery.
How do i overcome this?
SELECT LOG_REPO.UNIQ_ID,
LOG_REPO.REQUEST_PAYLOAD,
LOG_REPO.GEN_VAL,
LOG_REPO.CREATED_BY,
TO_CHAR(LOG_REPO.CREATED_DT,'DD/MM/YYYY') AS CREATED_DT,
HI_HDR.HI_NO R_VALUE,
HI_HDR.CREATED_BY R_CREATED_BY,
TO_CHAR(HI_HDR.CREATED_DT,'DD/MM/YYYY') AS R_CREATED_DT
FROM ATP_COMMON.VW_CMN_LOG_GEN_REPO LOG_REPO JOIN ATP_R.TBL_HI_HDR HI_HDR ON LOG_REPO.GEN_VAL = HI_HDR.HI_NO
WHERE NOT EXISTS
(SELECT NULL
FROM ATP_R.TBL_HI_HDR HI_HDR
WHERE LOG_REPO.GEN_VAL = HI_HDR.HI_NO
)
UNION ALL
SELECT LOG_REPO.UNIQ_ID,
LOG_REPO.REQUEST_PAYLOAD,
LOG_REPO.GEN_VAL,
LOG_REPO.CREATED_BY,
TO_CHAR(LOG_REPO.CREATED_DT,'DD/MM/YYYY') AS CREATED_DT,
HI_HDR.HI_NO R_VALUE,
HI_HDR.CREATED_BY R_CREATED_BY,
TO_CHAR(HI_HDR.CREATED_DT,'DD/MM/YYYY') AS R_CREATED_DT
FROM ATP_R.TBL_HI_HDR HI_HDR JOIN ATP_COMMON.VW_CMN_LOG_GEN_REPO LOG_REPO ON HI_HDR.HI_NO = LOG_REPO.GEN_VAL
WHERE NOT EXISTS
(SELECT NULL
FROM ATP_COMMON.VW_CMN_LOG_GEN_REPO LOG_REPO
WHERE HI_HDR.HI_NO = LOG_REPO.GEN_VAL
)
Full outer joins used to exclude all matching rows can be an expensive query. You don't supply much detail, but perhaps using NOT EXISTS would be simpler and maybe it will produce a better explain plan. Something along these lines.
select
cola,colb,colc
from t_master m
where not exists (
select null from a where m.keycol = a.fk_to_m
)
and not exists (
select null from b where m.keycol = b.fk_to_m
)
and not exists (
select null from c where m.keycol = c.fk_to_m
)
union all
select
cola,colb,colc from a
where not exists (
select null from t_master m where a.fk_to_m = m.keycol
)
union all
select
cola,colb,colc from b
where not exists (
select null from t_master m where b.fk_to_m = m.keycol
)
union all
select
cola,colb,colc from c
where not exists (
select null from t_master m where c.fk_to_m = m.keycol
)
You could union the 13 a,b,c ... tables to simplify the coding, but that may not perform so well.
Oracle 12.2
I have a SQL statement that is causing me issues. I am retrieving data from a table called BURNDOWN. If the user is an admin, they get to see all the data. If the user is NOT an admin, they are restricted to what they can see, based on some join conditions.
The issue I am running into is when the user is an ADMIN, I don’t need the other tables… subsequently, the JOIN condition is not relevant, so Oracle is deciding to do a cartesian join across everything…
How do I get around this so that is the user is an Admin, I only look at one table, else I look at all tables and include the join condition?
The example SQL is a contrived example, but it shows the issue.
Select
BURNDOWN.NAME,
BURNDOWN.ADDRESS,
BURNDOWN.STATE
from BURNDOWN, FILTER_A, FILTER_B, FILTER_C
Where
(
:ISAdmin = 1
Or
(
BURNDOWN.x=FILTER_A.x and
FILTER_A.y=FILTER_B.y and
FILTER_B.z=FILTER_C.z and
FILTER_C.user = :ThisUser
)
)
Use an EXISTS to see if the data exists in the FILTER tables without joining them in to the results.
select bd.*
from burndown bd
where ( :isadmin = 1 or
exists ( select 1
from filter_a a
inner join filter_b b on b.y = a.y
inner join filter_c c on c.z = b.z
where a.x = bd.x
and c.user = :ThisUser )
)
Presumably, you want:
select bd.*
from burndown bd
where :ISAdmin = 1 or
(exists (select 1 from FILTER_A a where bd.x = a.x) or
exists (select 1 from FILTER_B b where bd.y = b.y) or
exists (select 1 from FILTER_C c where bd.z = c.z)
);
I have a table in the database (big orange one) including parts and prices for two different type. I am looking to find the little orange table as result in summary:
I am looking for common parts in both type R and O Where price has gone up from type O to type R.
This is the script I tried but it is disconnected:
SELECT *FROM Table WHERE type='R'as a
SELECT * FROM Table WHERE type='O'as b
SELECT * FROM a
INNER JOIN b ON a.part = b.part
WHERE a.price < b.price
Please try this and let me know,
SELECT * FROM Table a, Table b
WHERE a.type = 'R'
and b.type = 'O'
and a.part = b.part
and a.price < b.price;
I just found the answer myself:
SELECT * INTO h
FROM table AS t
WHERE t.type='R';
SELECT * INTO b
FROM table AS tab
WHERE tab.type ='O';
SELECT h.type, h.part, h.price, b.price, (b.price - h.price) AS Gap
FROM h
INNER JOIN b ON h.part = b.part;
Going to use this query as a subquery, the problem is it returns many rows of duplicates. Tried to use COUNT() instead of exists, but it still returns a multiple answer.
Every table can only contain one record of superRef.
The below query I`ll use in SELECT col_a, [the CASE] From MyTable
SELECT CASE
WHEN
EXISTS (SELECT 1 FROM A WHERE
A_superRef = myTable.sysno AND A_specAttr = 'value')
THEN 3
WHEN EXISTS (SELECT 1 FROM B
INNER JOIN С ON С_ReferenceForB = B_sysNo WHERE C_superRef = myTable.sysno AND b_type = 2)
THEN 2
ELSE (SELECT C_intType FROM C
WHERE C_superRef = myTable.sysno)
END
FROM A, B, C
result:
3
3
3
3
3
3...
What if you did this? Because Im guessing you are getting an implicit full outer join A X B X C then running the case statement for each row in that result set.
SELECT CASE
WHEN
EXISTS (SELECT 1 FROM A WHERE
A_superRef = 1000001838012)
THEN 3
WHEN EXISTS (SELECT 1 FROM B
INNER JOIN С ON С_ReferenceForB = B_sysNo AND C_superRef = 1000001838012 )
THEN 2
ELSE (SELECT C_type FROM C
WHERE C_superRef = 1000001838012)
END
FROM ( SELECT COUNT(*) FROM A ) --This is a hack but should work in ANSI sql.
--Your milage my vary with different RDBMS flavors.
DUAL is what I needed, thanks to Thorsten Kettner
SELECT CASE
WHEN
EXISTS (SELECT 1 FROM A WHERE
A_superRef = 1000001838012)
THEN 3
WHEN EXISTS (SELECT 1 FROM B
INNER JOIN С ON С_ReferenceForB = B_sysNo AND C_superRef = 1000001838012 )
THEN 2
ELSE (SELECT C_type FROM C
WHERE C_superRef = 1000001838012)
END
FROM DUAL