Pardon the convoluted example, but I believe there is something fundamental about sql I am missing and I'm not sure what it is. I have this crazy query...
SELECT *
FROM (
SELECT *
FROM (
SELECT #t1 := #t1 +1 AS leaderboard_entry_youngness_rank, 1 - #t1 /100 AS
leaderboard_entry_youngness_based_on_expiry, leaderboard_entry . * ,
NOW( ) - leaderboard_entry_timestamp AS leaderboard_entry_age_in_some_units,
TO_DAYS( NOW( ) ) - TO_DAYS( leaderboard_entry_timestamp )
AS leaderboard_entry_age_in_days
FROM leaderboard_entry) AS inner_temp
NATURAL JOIN leaderboard
NATURAL JOIN user
WHERE (
leaderboard_load_key = 'sk-en-adjectives-1'
OR leaderboard_load_key = '-sk-en-adjectives-1'
)
AND leaderboard_quiz_mode = '0'
ORDER BY leaderboard_entry_age_in_some_units ASC , leaderboard_entry_timestamp ASC
LIMIT 0 , 100
) AS outer_temp
ORDER BY leaderboard_entry_elapsed_time_ms ASC , leaderboard_entry_timestamp ASC
LIMIT 0 , 50
I added the second nested SELECT statement because the user_name in the user table was not being returned in the outermost query. But now the leaderboard_entry_youngness_based_on_expiry field, which is being generated based on a row index ratio, is not working correctly.
If I remove the second nested SELECT statement, the leaderboard_entry_youngness_based_on_expiry works as expected, but the user_name column is not returned.
How can I satisfy both? Why is this happening?
Thanks!
This stems from the following question:
Add a numbered list column to a returned MySQL query
In your inner SELECT statement, you do not have user.user_name, that's why username is not returned. Remove the outer query, do it like earlier but with user.user_name like this:
....
SELECT #t1 := #t1 +1 AS leaderboard_entry_youngness_rank, 1 - #t1 /100 AS
leaderboard_entry_youngness_based_on_expiry, leaderboard_entry . * ,
NOW( ) - leaderboard_entry_timestamp AS leaderboard_entry_age_in_some_units,
TO_DAYS( NOW( ) ) - TO_DAYS( leaderboard_entry_timestamp )
AS leaderboard_entry_age_in_days, user.user_name
....
Try putting a ORDER BY in the inner most query, since there currently is no ORDER BY clause, its wrong to say that "is not working correctly".
Check if you take away the outer SELECT * FROM..., see if there are duplicate user_name columns.
BTW, Since you are not using the row index columns in your query, why not just put this logic in the application itself? it will be more reliable doing so.
Related
I have an oracle query as follows but when I make changes to pagination the results are different. what should i pass for my code
SELECT *
FROM (
SELECT b.*,
ROWNUM r__
FROM (
select a.KODE_KLAIM,
a.NO_SS,
a.LA,
a.NAMA_TK,
a.KODE_K,
(
select tk.TEM_LAHIR
from KN.VW_KN_TK tk
where tk.KODE_K = a.KODE_K and rownum=1
) TEM_LAHIR,
(
select TO_CHAR(tk.TLAHIR, 'DD/MM/RRRR')
from KN.VW_KTK tk
where tk.KODE_K = a.KODE_K
and rownum=1
) TLAHIR
from PN.KLAIM a
where nvl(a.STATUS_BATAL,'X') = 'T'
and A.NOMOR IS NOT NULL
and A.TIPE_KLAIM = 'JPN01'
)b
)
where 1 = 1
WHERE ROWNUM < ( ( ? * ? ) + 1 )
WHERE r__ >= ( ( ( ? - 1 ) * ? ) + 1 )
but i run this query i have result ORA-00900: invalid SQL statement
You have three WHERE clauses at the end (and no ORDER BY clause). To make it syntactically valid you could change the second and third WHERE clauses to AND.
However, you mention pagination so what you probably want is to use:
SELECT *
FROM (
SELECT b.*,
ROWNUM r__
FROM (
select ...
from ...
ORDER BY something
)b
WHERE ROWNUM < :page_size * :page_number + 1
)
WHERE r__ >= ( :page_number - 1 ) * :page_size + 1
Note: You can replace the named bind variables with anonymous bind variables if you want.
Or, if you are using Oracle 12 or later then you can use the OFFSET x ROWS FETCH FIRST y ROWS ONLY syntax:
select ...
from ...
ORDER BY something
OFFSET (:page_number - 1) * :page_size ROWS
FETCH FIRST :page_size ROWS ONLY;
Additionally, you have several correlated sub-queries such as:
select tk.TEM_LAHIR
from KN.VW_KN_TK tk
where tk.KODE_K = a.KODE_K and rownum=1
This will find the first matching row that the SQL engine happens to read from the datafile and is effectively finding a random row. If you want a specific row then you need an ORDER BY clause and you need to filter using ROWNUM AFTER the ORDER BY clause has been applied.
From Oracle 12, the correlated sub-query would be:
select tk.TEM_LAHIR
from KN.VW_KN_TK tk
where tk.KODE_K = a.KODE_K
ORDER BY something
FETCH FIRST ROW ONLY
I am trying to use COUNT(DISTINC column) OVER(PARTITION BY column) when I am using COUNT + window function(OVER).
I get an error like the one in the title and can't get it to work.
I have looked into how to deal with this error, but I have not found an example of how to deal with such a complex query as the one below.
I cannot find an example of how to deal with such a complex query as shown below, and I am not sure how to handle it.
The COUNT part of the problem exists on line 65.
How can such a complex query be resolved without slowing down?
WITH RECURSIVE "cte" AS((
SELECT
"videos_productvideocomment"."id",
"videos_productvideocomment"."user_id",
"videos_productvideocomment"."video_id",
"videos_productvideocomment"."parent_id",
"videos_productvideocomment"."text",
"videos_productvideocomment"."commented_at",
"videos_productvideocomment"."edited_at",
"videos_productvideocomment"."created_at",
"videos_productvideocomment"."updated_at",
"videos_productvideocomment"."id" AS "root_id"
FROM
"videos_productvideocomment"
WHERE
(
"videos_productvideocomment"."parent_id" IS NULL
AND "videos_productvideocomment"."video_id" = 'f264433c-c0af-49cc-8b40-84453da71b2d'
)
) UNION(
SELECT
"videos_productvideocomment"."id",
"videos_productvideocomment"."user_id",
"videos_productvideocomment"."video_id",
"videos_productvideocomment"."parent_id",
"videos_productvideocomment"."text",
"videos_productvideocomment"."commented_at",
"videos_productvideocomment"."edited_at",
"videos_productvideocomment"."created_at",
"videos_productvideocomment"."updated_at",
"cte"."root_id" AS "root_id"
FROM
"videos_productvideocomment"
INNER JOIN
"cte"
ON "videos_productvideocomment"."parent_id" = "cte"."id"
))
SELECT
*,
EXISTS(
SELECT
(1) AS "a"
FROM
"videos_productvideolikecomment" U0
WHERE
(
U0."comment_id" = t."id"
AND U0."user_id" = '3bd3bc86-0335-481e-9fd2-eb2fb1168f48'
)
LIMIT 1
) AS "liked"
FROM
(
SELECT DISTINCT
"cte"."id",
"cte"."created_at",
"cte"."updated_at",
"cte"."user_id",
"cte"."text",
"cte"."commented_at",
"cte"."edited_at",
"cte"."parent_id",
"cte"."video_id",
"cte"."root_id" AS "root_id",
COUNT(DISTINCT "cte"."root_id") OVER(PARTITION BY "cte"."root_id") AS "reply_count", <--- here
COUNT("videos_productvideolikecomment"."id") OVER(PARTITION BY "cte"."id") AS "liked_count"
FROM
"cte"
LEFT OUTER JOIN
"videos_productvideolikecomment"
ON (
"cte"."id" = "videos_productvideolikecomment"."comment_id"
)
) t
WHERE
t."id" = t."root_id"
ORDER BY
CASE
WHEN t."user_id" = '3bd3bc86-0335-481e-9fd2-eb2fb1168f48' THEN 0
ELSE 1
END ASC,
"liked_count" DESC
DISTINCT will look for duplicates and remove it, but in big data it will take a lot of time to process this query, you should process the middle of the record in the programming part I think it will be fast than. Thank
I have an SQL query in which I need to take the output of a subquery and use it more than once. My existing query works, but only if I repeat the subquery each time I need it. Unfortunately the subquery is complex, and takes time to execute - meaning that multiple iterations really slow the whole thing down.
I have read that you can use the "WITH" statement to assign a subquery output to a variable, in order to re-use that variable. However the problem I'm having is that within the subquery, I need to reference values from the main query. And it appears that if I use WITH - before the main query SELECT - then those references are not recognised. I'll give you a simplified example:
WITH
DateX AS
(
SELECT
MAX(TableSub.Date)
FROM
TableA TableSub
WHERE
TableSub.ID = TableMain.ID
AND TableSub.Event = 'AnotherEvent'
AND TableSub.Date BETWEEN '01-Jan-2015' AND '31-Dec-2015'
)
SELECT
TableMain.ID
FROM
TableA TableMain
WHERE
TableMain.Event = 'MainEvent'
AND TableMain.Date >= DateX
AND (
SELECT
TableSub2.ID
FROM
TableA TableSub2
WHERE
TableSub2.ID = TableMain.ID
TableSub2.Event = 'ThirdEvent'
AND TableSub2.Date <= DateX
) IS NULL
I hope this is clear. It's a simplified version of what I have, but you can see that DateX is used in more than one place: within the main query, and within a subquery. However the problem is that when DateX is defined by WITH, I need to link the ID back to the ID of the main query. And it's not working...
I would be grateful for any advice on this. Am I doing it wrong? Is there a way, or is it just impossible? If so, then should I be using another approach entirely? Thanks.
A better way:
SELECT ID
FROM (
SELECT ID,
"Date",
Event,
LAST_VALUE( CASE Event WHEN 'AnotherEvent' THEN "Date" END IGNORE NULLS )
OVER ( PARTITION BY ID ORDER BY "Date"
ROWS BETWEEN UNBOUNDED PRECEEDING AND UNBOUNDED FOLLOWING
) AS another_date,
FIRST_VALUE( CASE Event WHEN 'ThirdEvent' THEN "Date" END IGNORE NULLS )
OVER ( PARTITION BY ID ORDER BY "Date"
ROWS BETWEEN UNBOUNDED PRECEEDING AND UNBOUNDED FOLLOWING
) AS third_date
FROM TableA
WHERE Event IN ( 'MainEvent', 'ThirdEvent' )
OR ( Event = 'AnotherEvent' AND EXTRACT( YEAR FROM "Date" ) = 2015 )
)
WHERE Event = 'MainEvent'
AND "Date" >= another_date
AND ( third_date IS NULL OR third_date > another_date );
You need to join your DateX CTE on the ID column. Something like:
WITH
DateX AS
(
SELECT
TableSub.ID,
MAX(TableSub.Date) AS MaxDate
FROM
TableA TableSub
WHERE
AND TableSub.Event = 'AnotherEvent'
AND TableSub.Date >= DATE '2015-01-01'
AND TableSub.Date < DATE '2016-01-01'
GROUP BY
TableSub.ID
)
SELECT
TableMain.ID
FROM
TableA TableMain
JOIN
DateX
ON
DateX.ID = TableMain.ID
WHERE
TableMain.Event = 'MainEvent'
AND TableMain.Date >= DateX.MaxDate
AND (
SELECT
TableSub2.ID
FROM
TableA TableSub2
JOIN
DateX
ON
DateX.ID = TableSub2.ID
WHERE
TableSub2.ID = TableMain.ID
TableSub2.Event = 'ThirdEvent'
AND TableSub2.Date <= DateX.MaxDate
) IS NULL
The CTE also needs a column alias for the aggregate; and as you need to join in the ID, you need to include that and group by it.
The last subquery looks odd; you might want NOT EXISTS rather than IS NULL if you're looking for no record. Perhaps your real query is using an aggregate, but even so that might be quicker.
This still may not be the best approach but it's hard to tell from your example. Hitting the same table three times may be unnecessarily expensive.
I once wrote similar queries as below in oracle, and it worked at that time. now I try to do put this in prepareStatement of Derby JDBC.
SELECT THREADID,THREADID2,SIMILARITY FROM S WHERE
(THREADID,THREADID2) IN
(
SELECT T1.ID,T2.ID FROM
(
( SELECT T.ID FROM T WHERE T.POSTTYPEID = '1' ORDER BY ANSWERCOUNT DESC FETCH FIRST 200 ROWS ONLY ) AS T1
JOIN
( SELECT T.ID FROM T WHERE T.POSTTYPEID = '1' ORDER BY ANSWERCOUNT DESC FETCH FIRST 200 ROWS ONLY ) AS T2
)
)
It turned out that I got errors as:
java.sql.SQLSyntaxErrorException: Syntax error：Encountered "," at line 1, column 78
I checked the code, and this error points to the (THREADID,THREADID2) part, is it that this is not supported in JDBC Derby?
no
(THREADID,THREADID2) IN
not working
you must seperate like
WHERE THREADID IN ('your condition') OR THREADID2 IN ('your condition')
i am using Microsoft SQL Server 2008
i would like to save the result of a subquery to reuse it in a following subquery.
Is this possible?
What is best practice to do this? (I am very new to SQL)
My query looks like:
INSERT INTO [dbo].[TestTable]
(
[a]
,[b]
)
SELECT
(
SELECT TOP 1 MAT_WS_ID
FROM #TempTableX AS X_ALIAS
WHERE OUTERBASETABLE.LT_ALL_MATERIAL = X_ALIAS.MAT_RM_NAME
)
,(
SELECT TOP 1 MAT_WS_NAME
FROM #TempTableY AS Y_ALIAS
WHERE Y_ALIAS.MAT_WS_ID = MAT_WS_ID
--(
--SELECT TOP 1 MAT_WS_ID
--FROM #TempTableX AS X_ALIAS
--WHERE OUTERBASETABLE.LT_ALL_MATERIAL = X_ALIAS.MAT_RM_NAME
--)
)
FROM [dbo].[LASERTECHNO] AS OUTERBASETABLE
My question is:
Is this correct what i did.
I replaced the second SELECT Statement in the WHERE-Clause for [b] (which is commented out and exactly the same as for [a]), with the result of the first SELECT Statement of [a] (=MAT_WS_ID).
It seems to give the right results.
But i dont understand why!
I mean MAT_WS_ID is part of both temporary tables X_ALIAS and Y_ALIAS.
So in the SELECT statement for [b], in the scope of the [b]-select-query, MAT_WS_ID could only be known from the Y_ALIAS table. (Or am i wrong, i am more a C++, maybe the scope things in SQL and C++ are totally different)
I just wannt to know what is the best way in SQL Server to reuse an scalar select result.
Or should i just dont care and copy the select for every column and the sql server optimizes it by its own?
One approach would be outer apply:
SELECT mat.MAT_WS_ID
, (
SELECT TOP 1 MAT_WS_NAME
FROM #TempTableY AS Y_ALIAS
WHERE Y_ALIAS.MAT_WS_ID = mat.MAT_WS_ID
)
FROM [dbo].[LASERTECHNO] AS OUTERBASETABLE
OUTER APPLY
(
SELECT TOP 1 MAT_WS_ID
FROM #TempTableX AS X_ALIAS
WHERE OUTERBASETABLE.LT_ALL_MATERIAL = X_ALIAS.MAT_RM_NAME
) as mat
You could rank rows in #TempTableX and #TempTableY partitioning them by MAT_RM_NAME in the former and by MAT_WS_ID in the latter, then use normal joins with filtering by rownum = 1 in both tables (rownum being the column containing the ranking numbers in each of the two tables):
WITH x_ranked AS (
SELECT
*,
rownum = ROW_NUMBER() OVER (PARTITION BY MAT_RM_NAME ORDER BY (SELECT 1))
FROM #TempTableX
),
y_ranked AS (
SELECT
*,
rownum = ROW_NUMBER() OVER (PARTITION BY MAT_WS_ID ORDER BY (SELECT 1))
FROM #TempTableY
)
INSERT INTO dbo.TestTable (a, b)
SELECT
x.MAT_WS_ID,
y.MAT_WS_NAME
FROM dbo.LASERTECHNO t
LEFT JOIN x_ranked x ON t.LT_ALL_MATERIAL = x.MAT_RM_NAME AND x.rownum = 1
LEFT JOIN y_ranked y ON x.MAT_WS_ID = y.MAT_WS_ID AND y.rownum = 1
;
The ORDER BY (SELECT 1) bit is a trick to specify an indeterminate ordering, which, accordingly, would result in indeterminate rownum = 1 rows picked by the query. That is to more or less duplicate your TOP 1 without an explicit order, but I would recommend you to specify a more sensible ORDER BY clause to make the results more predictable.