To improve the performance of the following query we have to remove the OR clause and use UNION. OR clause does not allow the index to be considered that is why we need to use UNION instead. Kindly let me know if there is any other better way to improve the performance of this query and avoid using OR clause?
SELECT *
FROM A
LEFT OUTER JOIN B
ON A.NBR_CH = B.NBR_CH
LEFT OUTER JOIN C
ON B.ID = C.ID
WHERE A.LIS IN (:IdList)
AND ((C.TYP_C = :Type
AND C.R_NBR LIKE :rNbr)
OR (A.R_NBR LIKE :rNbr))
WITH UR
Would it be like this?
SELECT *
FROM A
LEFT OUTER JOIN B
ON A.NBR_CH = B.NBR_CH
LEFT OUTER JOIN C
ON B.ID = C.ID
WHERE A.LIS IN (:IdList)
AND ((C.TYP_C = :Type
AND C.R_NBR LIKE :rNbr))
WITH UR
UNION
SELECT *
FROM A
LEFT OUTER JOIN B
ON A.NBR_CH = B.NBR_CH
LEFT OUTER JOIN C
ON B.ID = C.ID
WHERE A.LIS IN (:IdList)
AND A.R_NBR LIKE :rNbr
WITH UR
The above is correct. But I wanted to know if there is any other way to do this without using the UNION
Related
What is the name|type of this query? Like inner join, outer join.
SELECT a.tutorial_id, a.tutorial_author, b.tutorial_count
FROM tutorials_tbl a, tcount_tbl b
WHERE a.tutorial_author = b.tutorial_author
It's an Implicit INNER JOIN most commonly found in older code. It is synonymous with:
SELECT a.tutorial_id,
a.tutorial_author,
b.tutorial_count
FROM tutorials_tbl a
INNER JOIN tcount_tbl b ON a.tutorial_author = b.tutorial_author
which is also synonymous with just using JOIN:
SELECT a.tutorial_id,
a.tutorial_author,
b.tutorial_count
FROM tutorials_tbl a
JOIN tcount_tbl b ON a.tutorial_author = b.tutorial_author
I have 3 tables :
A(k1,A) B(k1,k2,B) and C(k2,C).
I want to filter all A that satisfy C.k2 condition. in this example, I must filter go through table B : filter all B that have same k1 attribute with A , and filter all C k2 attribute with B (that I have filtered before).
I have an ugly way to do this :
select * from A where k1 in (select * .....) // it looks ugly and hard to trace
I have though about using join function, but don't really know how to do this. Please tell me a best way for this query.
Thanks :)
Try this Query.
select * from A
join b on a.k1 = b.k1
join c on c.k2 = b.k2
Explanation for JOIN
It sounds pretty easy:
select * from A
join B on B.k1 = A.k1
join C on C.k2 = B.k2
If I'm reading your table structure correctly, the join logic would be like this:
SELECT *
FROM A
JOIN B
ON A.k1 = B.k1
JOIN C
ON B.k2 = C.k2
You could of course then specify in the SELECT which table you want values from, ie:
SELECT A.*,C.*
Or Limit results with WHERE ie:
WHERE C.C = 'something'
Using join to retrieve data from two or more tables. see Join Fundamentals
SELECT A.k1,B.k2
FROM A
JOIN B ON A.k1 = B.k1
JOIN C ON B.k2 = C.k2
I have a query (exert from a stored procedure) that looks something like this:
SELECT S.name
INTO #TempA
from tbl_Student S
INNER JOIN tbl_StudentHSHistory TSHSH on TSHSH.STUD_PK=S.STUD_PK
INNER JOIN tbl_CODETAILS C
on C.CODE_DETL_PK=S.GID
WHERE TSHSH.Begin_date < #BegDate
Here is the issue, the 2nd inner join and corresponding where statement should only happen if only a certain variable (#UseArchive) is true, I don't want it to happen if it is false. Also, in TSHSH certain rows might have no corresponding entries in S. I tried splitting it into 2 separate queries based on #UseArchive but studio refuses to compile that because of the INTO #TempA statement saying that there is already an object named #TempA in the database. Can anyone tell me of a way to fix the query or a way to split the queries with the INTO #TempA statement?
Looks like you're asking 2 questions here.
1- How to fix the SELECT INTO issue:
SELECT INTO only works if the target table does not exist. You need to use INSERT INTO...SELECT if the table already exists.
2- Conditional JOIN:
You'll need to do a LEFT JOIN if the corresponding row may not exist. Try this.
SELECT S.name
FROM tbl_Student S
INNER JOIN tbl_StudentHSHistory TSHSH
ON TSHSH.STUD_PK=S.STUD_PK
LEFT JOIN tbl_CODETAILS C
ON C.CODE_DETL_PK=S.GID
WHERE TSHSH.Begin_date < #BegDate
AND CASE WHEN #UseArchive = 1 THEN c.CODE_DETL_PK ELSE 0 END =
CASE WHEN #UseArchive = 1 THEN S.GID ELSE 0 END
Putting the CASE statement in the WHERE clause and not the JOIN clause will force it to act like an INNER JOIN when #UseArchive and a LEFT JOIN when not.
I'd replace it with LEFT JOIN
LEFT JOIN tbl_CODETAILS C ON #UseArchive = 1 AND C.CODE_DETL_PK=S.GID
You can split the queries and then insert into a temp table easily.
SELECT * INTO #TempA FROM
(
SELECT * FROM Q1
UNION ALL
SELECT * FROM Q2
) T
SELECT S.name
INTO #TempA
from tbl_Student S
INNER JOIN tbl_StudentHSHistory TSHSH
on TSHSH.STUD_PK = S.STUD_PK
INNER JOIN tbl_CODETAILS C
on C.CODE_DETL_PK = S.GID
and #UseArchive = true
WHERE TSHSH.Begin_date < #BegDate
But putting #UseArchive = true in the join in this case is the same as where
Your question does not make much sense to me
So what if TSHSH certain rows might have no corresponding entries in S?
If you want just one of the joins to match
SELECT S.name
INTO #TempA
from tbl_Student S
LEFT OUTER JOIN tbl_StudentHSHistory TSHSH
on TSHSH.STUD_PK = S.STUD_PK
LEFT OUTER JJOIN tbl_CODETAILS C
on C.CODE_DETL_PK = S.GID
and #UseArchive = true
WHERE TSHSH.Begin_date < #BegDate
and ( TSHSH.STUD_PK is not null or C.CODE_DETL_PK id not null )
I am trying to execute the following sql query but it takes 22 seconds to execute. the number of returned items is 554192. I need to make this faster and have already put indexes in all the tables involved.
SELECT mc.name AS MediaName,
lcc.name AS Country,
i.overridedate AS Date,
oi.rating,
bl1.firstname + ' ' + bl1.surname AS Byline,
b.id BatchNo,
i.numinbatch ItemNumberInBatch,
bah.changedatutc AS BatchDate,
pri.code AS IssueNo,
pri.name AS Issue,
lm.neptunemessageid AS MessageNo,
lmt.name AS MessageType,
bl2.firstname + ' ' + bl2.surname AS SourceFullName,
lst.name AS SourceTypeDesc
FROM profiles P
INNER JOIN profileresults PR
ON P.id = PR.profileid
INNER JOIN items i
ON PR.itemid = I.id
INNER JOIN batches b
ON b.id = i.batchid
INNER JOIN itemorganisations oi
ON i.id = oi.itemid
INNER JOIN lookup_mediachannels mc
ON i.mediachannelid = mc.id
LEFT OUTER JOIN lookup_cities lc
ON lc.id = mc.cityid
LEFT OUTER JOIN lookup_countries lcc
ON lcc.id = mc.countryid
LEFT OUTER JOIN itembylines ib
ON ib.itemid = i.id
LEFT OUTER JOIN bylines bl1
ON bl1.id = ib.bylineid
LEFT OUTER JOIN batchactionhistory bah
ON b.id = bah.batchid
INNER JOIN itemorganisationissues ioi
ON ioi.itemorganisationid = oi.id
INNER JOIN projectissues pri
ON pri.id = ioi.issueid
LEFT OUTER JOIN itemorganisationmessages iom
ON iom.itemorganisationid = oi.id
LEFT OUTER JOIN lookup_messages lm
ON iom.messageid = lm.id
LEFT OUTER JOIN lookup_messagetypes lmt
ON lmt.id = lm.messagetypeid
LEFT OUTER JOIN itemorganisationsources ios
ON ios.itemorganisationid = oi.id
LEFT OUTER JOIN bylines bl2
ON bl2.id = ios.bylineid
LEFT OUTER JOIN lookup_sourcetypes lst
ON lst.id = ios.sourcetypeid
WHERE p.id = #profileID
AND b.statusid IN ( 6, 7 )
AND bah.batchactionid = 6
AND i.statusid = 2
AND i.isrelevant = 1
when looking at the execution plan I can see an step which is costing 42%. Is there any way I could get this to a lower threshold or any way that I can improve the performance of the whole query.
Remove the profiles table as it is not needed and change the WHERE clause to
WHERE PR.profileid = #profileID
You have a left outer join on the batchactionhistory table but also have a condition in your WHERE clause which turns it back into an inner join. Change you code to this:
LEFT OUTER JOIN batchactionhistory bah
ON b.id = bah.batchid
AND bah.batchactionid = 6
You don't need the batches table as it is used to join other tables which could be joined directly and to show the id in you SELECT which is also available in other tables. Make the following changes:
i.batchidid AS BatchNo,
LEFT OUTER JOIN batchactionhistory bah
ON i.batchidid = bah.batchid
Are any of the fields that are used in joins or the WHERE clause from tables that contain large amounts of data but are not indexed. If so try adding an index on at time to the largest table.
Do you need every field in the result - if you could loose one or to you maybe could reduce the number of tables further.
First, if this is not a stored procedure, make it one. That's a lot of text for sql server to complile.
Next, my experience is that "worst practices" are occasionally a good idea. Specifically, I have been able to improve performance by splitting large queries into a couple or three small ones and assembling the results.
If this query is associated with a .net, coldfusion, java, etc application, you might be able to do the split/re-assemble in your application code. If not, a temporary table might come in handy.
Below is my query using a left join that works as expected. What I want to do is add another table filter this query ever further but having trouble doing so. I will call this new table table_3 and want to add where table_3.rwykey = runways_updatable.rwykey. Any help would be very much appreciated.
SELECT *
FROM RUNWAYS_UPDATABLE
LEFT JOIN TURN_UPDATABLE
ON RUNWAYS_UPDATABLE.RWYKEY = TURN_UPDATABLE.RWYKEY
WHERE RUNWAYS_UPDATABLE.ICAO = 'ICAO'
AND (RUNWAYS_UPDATABLE.TORA > 4000 OR LDA > 0)
AND (TURN_UPDATABLE.AIRLINE_CODE IS NULL OR TURN_UPDATABLE.AIRLINE_CODE = ''
OR TURN_UPDATABLE.AIRLINE_CODE = '')
'*************EDIT To CLARIFY *****************
Here is the other statement that inner join i would like to use and I would like to combine these 2 statements.
SELECT *
FROM RUNWAYS_UPDATABLE A, RUNWAYS_TABLE B
WHERE A.RWYKEY = B.RWYKEY
'***What I have so far as advice taken below, but getting syntax error
SELECT RUNWAYS_UPDATABLE.*, TURN_UPDATABLE.*, AIRPORT_RUNWAYS_SELECTED.*
FROM RUNWAYS_UPDATABLE
INNER JOIN AIRPORT_RUNWAYS_SELECTED
ON RUNWAYS_UPDATABLE.RWYKEY = AIRPORT_RUNWAYS_SELECTED.RWYKEY
LEFT JOIN TURN_UPDATABLE
ON RUNWAYS_UPDATABLE.RWYKEY = TURN_UPDATABLE.RWYKEY
NOTE: If i comment out the inner join and leave the left join or vice versa, it works but when I have both of joins in the query, thats when im getting the syntax error.
I always come across this question when searching for how to make LEFT JOIN depend on a further INNER JOIN. Here is an example for what I am searching when I am searching for "using LEFT JOIN and INNER JOIN in the same query":
SELECT *
FROM foo f1
LEFT JOIN (bar b1
INNER JOIN baz b2 ON b2.id = b1.baz_id
) ON
b1.id = f1.bar_id
In this example, b1 will only be included if b2 is also found.
Remember that filtering a right-side table in left join should be done in join itself.
select *
from table1
left join table2
on table1.FK_table2 = table2.id
and table2.class = 'HIGH'
I finally figured it out. Thanks for all your help!!!
SELECT * FROM
(AIRPORT_RUNWAYS_SELECTED
INNER JOIN RUNWAYS_UPDATABLE
ON AIRPORT_RUNWAYS_SELECTED.RWYKEY = RUNWAYS_UPDATABLE.RWYKEY)
LEFT JOIN TURN_UPDATABLE ON RUNWAYS_UPDATABLE.RWYKEY = TURN_UPDATABLE.RWYKEY
Add your INNER_JOIN before your LEFT JOIN:
SELECT *
FROM runways_updatable ru
INNER JOIN table_3 t3 ON ru.rwykey = t3.rwykey
LEFT JOIN turn_updatable tu
ON ru.rwykey = tu.rwykey
AND (tu.airline_code IS NULL OR tu.airline_code = '' OR tu.airline_code = '')
WHERE ru.icao = 'ICAO'
AND (ru.tora > 4000 OR ru.lda > 0)
If you LEFT JOIN before your INNER JOIN, then you will not get results from table_3 if there is no matching row in turn_updatable. It's possible this is what you want, but since your join condition for table_3 only references runways_updatable, I would assume that you want a result from table_3, even if there isn't a matching row in turn_updatable.
EDIT:
As #NikolaMarkovinović pointed out, you should filter your LEFT JOIN in the join condition itself, as you see above. Otherwise, you will not get results from the left-side table (runways_updatable) if that condition isn't met in the right-side table (turn_updatable).
EDIT 2: OP mentioned this is actually Access, and not MySQL
In Access, perhaps it's a difference in the table aliases. Try this instead:
SELECT [ru].*, [tu].*, [ars].*
FROM [runways_updatable] AS [ru]
INNER JOIN [airport_runways_selected] AS [ars] ON [ru].rwykey = [ars].rwykey
LEFT JOIN [turn_updatable] AS [tu]
ON [ru].rwykey = [tu].rwykey
AND ([tu].airline_code IS NULL OR [tu].airline_code = '' OR [tu].airline_code = '')
WHERE [ru].icao = 'ICAO'
AND ([ru].tora > 4000 OR [ru].lda > 0)
If it is just an inner join that you want to add, then do this. You can add as many joins as you want in the same query. Please update your answer if this is not what you want, though
SELECT *
FROM RUNWAYS_UPDATABLE
LEFT JOIN TURN_UPDATABLE
ON RUNWAYS_UPDATABLE.RWYKEY = TURN_UPDATABLE.RWYKEY
INNER JOIN table_3
ON table_3.rwykey = runways_updatable.rwykey
WHERE RUNWAYS_UPDATABLE.ICAO = 'ICAO'
AND (RUNWAYS_UPDATABLE.TORA > 4000 OR LDA > 0)
AND (TURN_UPDATABLE.AIRLINE_CODE IS NULL OR TURN_UPDATABLE.AIRLINE_CODE = ''
OR TURN_UPDATABLE.AIRLINE_CODE = '')
I am not really sure what you want. But maybe something like this:
SELECT RUNWAYS_UPDATABLE.*, TURN_UPDATABLE.*
FROM RUNWAYS_UPDATABLE
JOIN table_3
ON table_3.rwykey = runways_updatable.rwykey
LEFT JOIN TURN_UPDATABLE
ON RUNWAYS_UPDATABLE.RWYKEY = TURN_UPDATABLE.RWYKEY
WHERE RUNWAYS_UPDATABLE.ICAO = 'ICAO'
AND (RUNWAYS_UPDATABLE.TORA > 4000 OR LDA > 0)
AND (TURN_UPDATABLE.AIRLINE_CODE IS NULL OR TURN_UPDATABLE.AIRLINE_CODE = ''
OR TURN_UPDATABLE.AIRLINE_CODE = '')
For Postgres, query planner does not guarantee order of execution of join. To Guarantee one can use #Gajus solution but the problem arises if there are Where condition for inner join table's column(s). Either one would to require to carefully add the where clauses in the respective Join condition or otherwise it is better to use subquery the inner join part, and left join the output.