I need to update a few thousand rows in my Postgres table using the result of a array_agg and spatial lookup.
The query needs to take the geometry of the parent table, and return an array of the matching row IDs in the other table. It may return no IDs or potentially 2-3 IDs.
I've tried to use an UPDATE FROM but I can't seem to pass into the subquery the parent table geom column for the SELECT. I can't see any way of doing a JOIN between the 2 tables.
Here is what I currently have:
UPDATE lrc_wales_data.records
SET lrc_array = subquery.lrc_array
FROM (
SELECT array_agg(wales_lrcs.gid) AS lrc_array
FROM layers.wales_lrcs
WHERE st_dwithin(records.geom_poly, wales_lrcs.geom, 0)
) AS subquery
WHERE records.lrc = 'nrw';
The error I get is:
ERROR: invalid reference to FROM-clause entry for table "records"
LINE 7: WHERE st_dwithin(records.geom_poly, wales_lrcs.geom, 0)
Is this even possible?
Many thanks,
Steve
Realised there was no need to use SET FROM. I could just use a sub query directly in the SET:
UPDATE lrc_wales_data.records
SET lrc_array = (
SELECT array_agg(wales_lrcs.gid) AS lrc
FROM layers.wales_lrcs
WHERE st_dwithin(records.geom_poly, wales_lrcs.geom, 0)
)
WHERE records.lrc = 'nrw';
Related
Sample data:
I am trying update a column with values from multiple columns in another table if two columns match.
Consider the following query:
UPDATE application_table
SET asset_list = asset_table.asset_name
FROM asset_table
WHERE application_table.application_name = asset_table.applications;
My table structure is:
application_table:
"asset_list"; "text[]"
"application_name"; "character varying"
asset_table:
"asset_name"; "character varying"
"applications"; "character varying"
I get the following error:
ERROR: column "asset_list" is of type text[] but expression is of type character varying
Line 12 SET asset_list = asset_table.asset_name
What you need to do is aggregate the asset_name per applications value and set asset_list to that aggregated value.
Problem is you can't do something like
UPDATE ..
SET asset_list = ARRAY_AGG(asset_name)
FROM ...
because aggregate functions are not allowed in updates like that.
So here's two other ways to do it:
UPDATE app_table
SET asset_list = _asset_list
FROM (
SELECT applications, ARRAY_AGG(asset_name ORDER BY asset_name) AS _asset_list
FROM asset_table
GROUP BY applications
) AS a
WHERE app_name = applications;
https://www.db-fiddle.com/f/pKB5k6Lexwzqv6ZbCCdJay/0
This first builds a result set of distinct application names and an array of all the asset_names for each of the app names. Then it updates the table as usual with that array value.
Another way is:
UPDATE app_table
SET asset_list = (SELECT ARRAY_AGG(asset_name ORDER BY asset_name)
FROM asset_table
WHERE applications = app_name)
;
https://www.db-fiddle.com/f/8oVWsubXW93n142gtZYLXB/0
This will update every record in app_table, and calculates the array value on the fly for every record.
I have the following code in Postgres
select op.url from identity.legal_entity le
join identity.profile op on le.legal_entity_id =op.legal_entity_id
where op.global_id = '8wyvr9wkd7kpg1n0q4klhkc4g'
which returns 1 row.
Then I try to update the url field with the following:
update identity.profile
set url = 'htpp:sam'
where identity.profile.url in (
select op.url from identity.legal_entity le
join identity.profile op on le.legal_entity_id =op.legal_entity_id
where global_id = '8wyvr9wkd7kpg1n0q4klhkc4g'
);
But the above ends up updating more than 1 row, actually all of the rows of the identity table.
I would assume since the first postgres statement returns one row, only one row at most can be updated, but I am getting the wrong effect where all of the rows are being updated. Why ?? Please help a nubie fix the above update statement.
Instead of using profile.url to identify the row you want to update, use the primary key. That is what it is there for.
So if the primary key column is called id, the statement could be modified to:
UPDATE identity.profile
SET ...
WHERE identity.profile.id IN (SELECT op.id FROM ...);
But you can do this much simpler in PostgreSQL with
UPDATE identity.profile op
SET url = 'htpp:sam'
FROM identity.legal_entity le
WHERE le.legal_entity_id = op.legal_entity_id
AND le.global_id = '8wyvr9wkd7kpg1n0q4klhkc4g';
I was having some trouble with an SQL 2k sproc and which we moved to SQL 2k5 so we could used Table Value UDF's instead of Scalar UDF's.
This is simplified, but this is my problem.
I have a temporary table that I fill up with product information. I then pass that product information into a UDF and return the information back to my main results set. It doesn't seem to work.
Am I not allowed to pass a Temporary Table value into an CROSS APPLY'd Table Value UDF?
--CREATE AND FILL #brandInfo
SELECT sku, upc, prd_id, cp.customerPrice
FROM products p
JOIN #brandInfo b ON p.brd_id=b.brd_id
CROSS APPLY f_GetCustomerPrice(b.priceAdjustmentValue, b.priceAdjustmentAmount, p.Price) cp
--f_GetCUstomerPrice uses the AdjValue, AdjAmount, and Price to calculate users actual price
When I put dummy values in for b.priceAdjustmentValue and b.priceAdjustmentAmount it works great. But as soon as I try to load the temp table values in it bombs.
Msg 207, Level 16, State 1, Line 140
Invalid column name 'b.priceAdjustmentValue'.
Msg 207, Level 16, State 1, Line 140
Invalid column name 'b.priceAdjustmentAmount'.
Have you tried:
--CREATE AND FILL #brandInfo
SELECT sku, upc, prd_id, cp.customerPrice
FROM products p
JOIN #brandInfo b ON p.brd_id=b.brd_id
CROSS APPLY (
SELECT *
FROM f_GetCustomerPrice(b.priceAdjustmentValue, b.priceAdjustmentAmount, p.Price) cp
)
--f_GetCUstomerPrice uses the AdjValue, AdjAmount, and Price to calculate users actual price
Giving the UDF the proper context in order to resolve the column references?
EDIT:
I have built the following UDF in my local Northwind 2005 database:
CREATE FUNCTION dbo.f_GetCustomerPrice(#adjVal DECIMAL(28,9), #adjAmt DECIMAL(28,9), #price DECIMAL(28,9))
RETURNS TABLE
AS RETURN
(
SELECT Level = 'One', AdjustValue = #adjVal, AdjustAmount = #adjAmt, Price = #price
UNION
SELECT Level = 'Two', AdjustValue = 2 * #adjVal, AdjustAmount = 2 * #adjAmt, Price = 2 * #price
)
GO
And referenced it in the following query without issue:
SELECT p.ProductID,
p.ProductName,
b.CompanyName,
f.Level
FROM Products p
JOIN Suppliers b
ON p.SupplierID = b.SupplierID
CROSS APPLY dbo.f_GetCustomerPrice(p.UnitsInStock, p.ReorderLevel, p.UnitPrice) f
Are you certain that your definition of #brandInfo has the priceAdjustmentValue and priceAdjustmentAmount columns defined on it? More importantly, if you are putting this in a stored procedure as you mentioned, does there exist a #brandInfo table already without those columns defined? I know #brandInfo is a temporary table, but if it exists at the time you attempt to create the stored procedure and it lacks the columns, the parsing engine may be getting tripped up. Oddly, if the table doesn't exist at all, the parsing engine simply glides past the missing table and creates the SP for you.
I'm using PostgreSQL + PostGIS.
In table I have a point and line geometry in the same column of the same table, in different rows. To get the line I run:
SELECT the_geom
FROM filedata
WHERE id=3
If i want to take point I run:
SELECT the_geom
FROM filedata
WHERE id=4
I want take point and line together, like they're shown in this WITH expression, but using a real query against the table instead:
WITH data AS (
SELECT 'LINESTRING (50 40, 40 60, 50 90, 30 140)'::geometry AS road,
'POINT (60 110)'::geometry AS poi)
SELECT ST_AsText(
ST_Line_Interpolate_Point(road, ST_Line_Locate_Point(road, poi))) AS projected_poi
FROM data;
You see in this example data comes from a hand-created WITH expression. I want take it from my filedata table. My problem is i dont know how to work with data from two different rows of one table at the same time.
One possible way:
A subquery to retrieve another value from a different row.
SELECT ST_AsText(
ST_Line_Interpolate_Point(
the_geom
,ST_Line_Locate_Point(
the_geom
,(SELECT the_geom FROM filedata WHERE id = 4)
)
)
) AS projected_poi
FROM filedata
WHERE id = 3;
Use a self-join:
SELECT ST_AsText(
ST_Line_Interpolate_Point(fd_road.the_geom, ST_Line_Locate_Point(
fd_road.the_geom,
fd_poi.the_geom
)) AS projected_poi
FROM filedata fd_road, filedata fd_poi
WHERE fd_road.id = 3 AND fd_poi.id = 4;
Alternately use a subquery to fetch the other row, as Erwin pointed out.
The main options for using multiple rows from one table in a single expression are:
Self-join the table with two different aliases as shown above, then filter the rows;
Use a subquery expression to get a value for all but one of the rows, as Erwin's answer shows;
Use a window function like lag() and lead() to get a row relative to the current row within the query result; or
JOIN on a subquery that returns a table
The latter two are more advanced options that solve problems that're difficult or inefficient to solve with the simpler self-join or subquery expression.
I have a table where I have added a new column, and I want to write a SQL statement to update that column based on existing information. Here are the two tables and the relevant columns
'leagues'
=> id
=> league_key
=> league_id (this is the new column)
'permissions'
=> id
=> league_key
Now, what I want to do, in plain English, is this
Set leagues.league_id to be permissions.id for each value of permissions.league_key
I had tried SQL like this:
UPDATE leagues
SET league_id =
(SELECT id FROM permissions WHERE league_key =
(SELECT distinct(league_key) FROM leagues))
WHERE league_key = (SELECT distinct(league_key) FROM leagues)
but I am getting an error message that says
ERROR: more than one row returned by a subquery used as an expression
Any help for this would be greatly appreciated
Based on your requirements of
Set leagues.league_id to be permissions.id for each value of permissions.league_key
This does that.
UPDATE leagues
SET league_id = permissions_id
FROM permissions
WHERE permissions.league_key = leagues.league_key;
When you do a subquery as an expression, it can't return a result set. Your subquery must evaluate to a single result. The error that you are seeing is because one of your subqueries returns more than one value.
Here is the relevant documentation for pg84: