I have this:
SELECT ROW_NUMBER() OVER (ORDER BY vwmain.ch) as RowNumber,
vwmain.vehicleref,vwmain.capid,
vwmain.manufacturer,vwmain.model,vwmain.derivative,
vwmain.isspecial,
vwmain.created,vwmain.updated,vwmain.stocklevel,
vwmain.[type],
vwmain.ch,vwmain.co2,vwmain.mpg,vwmain.term,vwmain.milespa
FROM vwMain_LATEST vwmain
INNER JOIN HomepageFeatured
on vwMain.vehicleref = homepageFeatured.vehicleref
WHERE homepagefeatured.siteskinid = 1
AND homepagefeatured.Rotator = 1
AND RowNumber = 1
ORDER BY homepagefeatured.orderby
It fails on "Invalid column name RowNumber"
Not sure how to prefix it to access it?
Thanks
You can't reference the field like that. You can however use a subquery or a common-table-expression:
Here's a subquery:
SELECT *
FROM (
SELECT ROW_NUMBER() OVER (ORDER BY vwmain.ch) as RowNumber,
vwmain.vehicleref,vwmain.capid,
vwmain.manufacturer,vwmain.model,vwmain.derivative,
vwmain.isspecial,
vwmain.created,vwmain.updated,vwmain.stocklevel,
vwmain.[type],
vwmain.ch,vwmain.co2,vwmain.mpg,vwmain.term,vwmain.milespa,
homepagefeatured.orderby
FROM vwMain_LATEST vwmain
INNER JOIN HomepageFeatured on vwMain.vehicleref = homepageFeatured.vehicleref
WHERE homepagefeatured.siteskinid = 1
AND homepagefeatured.Rotator = 1
) T
WHERE RowNumber = 1
ORDER BY orderby
Rereading your query, since you aren't partitioning by any fields, the order by at the end is useless (it contradicts the order of the ranking function). You're probably better off using top 1...
Using top:
SELECT top 1 vwmain.vehicleref,vwmain.capid,
vwmain.manufacturer,vwmain.model,vwmain.derivative,
vwmain.isspecial,
vwmain.created,vwmain.updated,vwmain.stocklevel,
vwmain.[type],
vwmain.ch,vwmain.co2,vwmain.mpg,vwmain.term,vwmain.milespa,
homepagefeatured.orderby
FROM vwMain_LATEST vwmain
INNER JOIN HomepageFeatured on vwMain.vehicleref = homepageFeatured.vehicleref
WHERE homepagefeatured.siteskinid = 1
AND homepagefeatured.Rotator = 1
ORDER BY homepagefeatured.orderby
(EDIT: This answer is a nearby pitfall. I leave it for documentation.)
Have a look here: Referring to a Column Alias in a WHERE Clause
This is the same situation.
It is a matter of how the sql query is parsed/compiled internally, so your field alias names are not known at the time the where clause is interpreted. Therefore you might try, in reference to the example above:
SELECT ROW_NUMBER() OVER (ORDER BY vwmain.ch) as RowNumber,
vwmain.vehicleref,vwmain.capid, vwmain.manufacturer,vwmain.model,vwmain.derivative, vwmain.isspecial,vwmain.created,vwmain.updated,vwmain.stocklevel, vwmain.[type],
vwmain.ch,vwmain.co2,vwmain.mpg,vwmain.term,vwmain.milespa
FROM vwMain_LATEST vwmain
INNER JOIN HomepageFeatured on vwMain.vehicleref = homepageFeatured.vehicleref
WHERE homepagefeatured.siteskinid = 1
AND homepagefeatured.Rotator = 1
AND ROW_NUMBER() OVER (ORDER BY vwmain.ch) = 1
ORDER BY homepagefeatured.orderby
Thus you see your expression in the select statement is exactly reused in the where clause.
Related
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 the following SQL Query:
select
distinct
Equipment_Reserved.Equipment_Attached_To,
Equipment.Name
from
Equipment,
Studies,
Equipment_Reserved
where
Studies.Study = 'MAINT19-01'
and
Equipment.idEquipment = Equipment_Reserved.Equipment_idEquipment
and
Studies.idStudies = Equipment_Reserved.Studies_idStudies
and
Equipment.Type = 'Probe'
This query produces the following results:
Equipment_Attached_To Name
2297 R1-P1
2297 R1-P2
2299 R1-P3
I would like to change it to the following:
Equipment_Attached_To Name1 Name2
2297 R1-P1 R1-P2
2299 R1-P3 NULL
Thanks for your help!
I'd first change your query from the old, legacy JOIN syntax to an explicit join as it makes the query easier to understand:
SELECT
DISTINCT
Equipment_Reserved.Equipment_Attached_To,
Equipment.Name
FROM
Equipment
INNER JOIN Equipment_Reserved ON Equipment_Reserved.Equipment_idEquipment = Equipment.idEquipment
INNER JOIN Studies ON Studies.idStudies = Equipment_Reserved.Studies_idStudies
WHERE
Studies.Study = 'MAINT19-01'
AND
Equipment.Type = 'Probe'
I don't think you actually need a PIVOT - I think you can do this with a nested query with the ROW_NUMBER function. I've seen that PIVOT queries often have worse query execution plans than nested-queries.
Let's add ROW_NUMBER (which require an ORDER BY as it's a windowing-function) and a matching ORDER BY in the whole query to make it consistent). Let's also use PARTITION BY so it resets the row-number for each Equipment_Attached_To value:
SELECT
DISTINCT
Equipment_Reserved.Equipment_Attached_To,
Equipment.Name,
ROW_NUMBER() OVER (PARTITION BY Equipment_Attached_To ORDER BY [Name]) AS RowNumber
FROM
Equipment
INNER JOIN Equipment_Reserved ON Equipment_Reserved.Equipment_idEquipment = Equipment.idEquipment
INNER JOIN Studies ON Studies.idStudies = Equipment_Reserved.Studies_idStudies
WHERE
Studies.Study = 'MAINT19-01'
AND
Equipment.Type = 'Probe'
ORDER BY
Equipment_Attached_To,
[Name]
This will give output like this:
Equipment_Attached_To Name RowNumber
2297 R1-P1 1
2297 R1-P2 2
2299 R1-P3 1
This can then be split out into explicit columns like so below. The use of MAX() is arbitrary (we could use MIN() instead) and only because we're dealing with a GROUP BY and because the CASE WHEN... restricts the input set to just 1 row anyway.
SELECT
Equipment_Attached_To,
MAX( CASE WHEN RowNumber = 1 THEN [Name] END ) AS Name1,
MAX( CASE WHEN RowNumber = 2 THEN [Name] END ) AS Name2
FROM
(
-- the query from above
)
GROUP BY
Equipment_Attached_To
ORDER BY
Equipment_Attached_To,
Name1,
Name2
So the final query is:
SELECT
Equipment_Attached_To,
MAX( CASE WHEN RowNumber = 1 THEN [Name] END ) AS Name1,
MAX( CASE WHEN RowNumber = 2 THEN [Name] END ) AS Name2
FROM
(
SELECT
DISTINCT
Equipment_Reserved.Equipment_Attached_To,
Equipment.Name,
ROW_NUMBER() OVER (PARTITION BY Equipment_Attached_To ORDER BY [Name]) AS RowNumber
FROM
Equipment
INNER JOIN Equipment_Reserved ON Equipment_Reserved.Equipment_idEquipment = Equipment.idEquipment
INNER JOIN Studies ON Studies.idStudies = Equipment_Reserved.Studies_idStudies
WHERE
Studies.Study = 'MAINT19-01'
AND
Equipment.Type = 'Probe'
)
GROUP BY
Equipment_Attached_To
ORDER BY
Equipment_Attached_To,
Name1,
Name2
Let's start with some basics.
To facilitate reading the code, I added alias to the tables using their initials.
Then, I converted the old join syntax which is partly deprecated to use the standard syntax since 1992 (27 years and people still use the old syntax).
Finally, since there are only 2 possible values, we can use MIN and MAX to separate them in 2 columns.
And because we're using aggregate functions, we remove the DISTINCT and use GROUP BY
The code now looks like this:
SELECT er.Equipment_Attached_To,
--Gets the first row for the id
MIN( e.Name) AS Name1,
--If the MAX is equal to the MIN, returns a NULL. If not, it returns the second value.
NULLIF( MAX(e.Name), MIN( e.Name)) AS Name2
FROM Equipment e
JOIN Studies s ON s.idStudies = er.Studies_idStudies
JOIN Equipment_Reserved er ON e.idEquipment = er.Equipment_idEquipment
WHERE s.Study = 'MAINT19-01'
AND e.Type = 'Probe'
GROUP BY er.Equipment_Attached_To;
I have the following code which selects value from table2 when 'some string' occurs more than once in 1990
SELECT a.value, COUNT(*) AS test
FROM table1 c
JOIN table2 a
ON c.value2 = a.value_2
JOIN table3 o
ON c.value3 = o.value_3
AND o.value4 = 1990
WHERE c.string = 'Some string'
GROUP BY a.value
HAVING COUNT(*) > 1
This works fine but I am attempting to write a query that produces a similar result without using aggregation. I just need to select values with more then 1 c.string and select those rather than counting and selecting the count as well. I thought about searching for pairs of 'some string' occurring in 1990 for a value but am unsure of how to execute this. Pointing me in the right direction would be appreciated! Struggling to find any documentation referencing this. Thank you!
Use window function ROW_NUMBER() to assign a sequence number within the rows of each table2.value. And use window function FIRST_VALUE() to get the largest row number for each table2.value. Use DISTINCT to remove the duplicates:
select distinct value, first_value(rn) over ( order by rn desc) as count
from
(
SELECT a.value , row_number() over (partition by a.value order by null) rn
FROM table1 c
JOIN table2 a
ON c.value2 = a.value_2
JOIN table3 o
ON c.value3 = o.value_3
AND o.value4 = 1990
WHERE c.string = 'Some string' ) t
where rn > 1;
To check for duplicates, you can use 'WHERE EXISTS', as a starting point. You could start by reading this:
https://www.w3schools.com/sql/sql_exists.asp
This will give you quite a long, cumbersome piece of code compared to using aggregation. But I expect that's the point of the task - to show how useful aggregation is.
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.
I need to use ROW_NUMBER() in the following Query to return rows 5 to 10 of the result. Can anyone please show me what I need to do? I've been trying to no avail. If anyone can help I'd really appreciate it.
SELECT *
FROM villa_data
INNER JOIN villa_prices
ON villa_prices.starRating = villa_data.starRating
WHERE villa_data.capacity >= 3
AND villa_data.bedrooms >= 1
AND villa_prices.period = 'lowSeason'
ORDER BY villa_prices.price,
villa_data.bedrooms,
villa_data.capacity
You need to stick it in a table expression to filter on ROW_NUMBER. You won't be able to use * as it will complain about the column name starRating appearing more than once so will need to list out the required columns explicitly. This is better practice anyway.
WITH CTE AS
(
SELECT /*TODO: List column names*/
ROW_NUMBER()
OVER (ORDER BY villa_prices.price,
villa_data.bedrooms,
villa_data.capacity) AS RN
FROM villa_data
INNER JOIN villa_prices
ON villa_prices.starRating = villa_data.starRating
WHERE villa_data.capacity >= 3
AND villa_data.bedrooms >= 1
AND villa_prices.period = 'lowSeason'
)
SELECT /*TODO: List column names*/
FROM CTE
WHERE RN BETWEEN 5 AND 10
ORDER BY RN
You can use a with clause. Please try the following
WITH t AS
(
SELECT villa_data.starRating,
villa_data.capacity,
villa_data.bedrooms,
villa_prices.period,
villa_prices.price,
ROW_NUMBER() OVER (ORDER BY villa_prices.price,
villa_data.bedrooms,
villa_data.capacity ) AS 'RowNumber'
FROM villa_data
INNER JOIN villa_prices
ON villa_prices.starRating = villa_data.starRating
WHERE villa_data.capacity >= 3
AND villa_data.bedrooms >= 1
AND villa_prices.period = 'lowSeason'
)
SELECT *
FROM t
WHERE RowNumber BETWEEN 5 AND 10;