I have two table a and b.
I want to update the row in table a that is the most recent insert for each id from the earliest insert in table b where a.id = b.id
I've been trying to use an update statement with a sub select in the from.
If I execute the sub query on its own it returns x number of rows, however when I execute the whole update statement it updated y number of rows.
update a
set title = b.title
created_at = b.created_at
from
(
select
e.id,e.title,e.created_at
from
(
select
l.id,
l.title,
l.created_at
l.t_insert
from b l
left join b r
l.id = r.id and l.t_insert > r.t_insert
) e
join
(
select
l.id,
l.title,
l.created_at,
l.t_insert
from a l
left join a r on l.report_id = r.report_id and l.t_insert <
r.t_insert
) f
)
where
a.id=b.id
I want the same number of rows to be updated as returned in the sub select query in the from.
In this case, having fewer rows updated than returned by the subquery could be because one row id is returned more than once in the subquery. If that happens, the update statement will still only update the row once. I'm assuming the statement you've provided is not exactly what you're running, but you should check that the subquery is not providing duplicates in the id field of the subquery (either using DISTINCT or GROUP BY or by double checking your JOIN conditions.
Related
In my query there is a value that will not match in the demand category table. Therefore, since one value does not match in the output of my query, other matching values do not appear.
I want to do;
How can I list other matching values even if there is an unmatched value in the query?
process Table
fk_unit_id fk_unit_position fk_demand_category
1 2 1
unit table
unit_id
1
unit_position table
unit_position
2
demand_category table
demand_category
1
Query:
SELECT unit_name,unit_position_name,demand_category_name From process
INNER JOIN unit ON process.fk_unit_id = unit_id and unit_id =1
INNER JOIN unit_position ON process.fk_unit_position_id = unit_position_id and unit_position_id = 2
INNER JOIN demand_category ON process.fk_demand_category_id = demand_category_id and demand_category_id =0 ;
Switch INNER JOIN on demand_category with LEFT JOIN
LEFT JOIN gets all records from the LEFT linked and the related record from the right table ,but if you have selected some columns from the RIGHT table, if there is no related records, these columns will contain NULL.
SELECT unit_name,unit_position_name,demand_category_name From process
INNER JOIN unit ON process.fk_unit_id = unit_id and unit_id =1
INNER JOIN unit_position ON process.fk_unit_position_id = unit_position_id and unit_position_id = 2
LEFT JOIN demand_category ON process.fk_demand_category_id = demand_category_id and demand_category_id =0 ;
You can use outer join to have the columns that don't match, just the corresponding values in other table will be padded with null. Other way is to use IN operator, but slower query performance.
Given that I have a list of repeating ids that I need to fetch some additional data to populate xls spreadsheet, how can I do that. "IN" clause returns only 1 match, but I need a row for each occurrence of an Id. I looked at PIVOT, thinking I could create a select list and then do inner join.
Select m.Id, m.LegalName, m.OtherId
from MyTable m
where m.OtherId in (1,2,1,1,3,1,4,4,2,1)
You can use VALUES clause :
SELECT t.id as OtherId, m.id, m.LegalName
FROM ( VALUES (1),(2),(1),(1),(3),(1),(4),(4),(2),(1)
) t(ID) INNER JOIN
MyTable m
ON m.OtherId = t.id;
I have two tables: contracts and contract_descriptions.
On contract_descriptions there is a column named contract_id which is equal on contracts table records.
I am trying to join the latest record on contract_descriptions:
SELECT *
FROM contracts c
LEFT JOIN contract_descriptions d ON d.contract_id = c.contract_id
AND d.date_description =
(SELECT MAX(date_description)
FROM contract_descriptions t
WHERE t.contract_id = c.contract_id)
It works, but is it the performant way to do it? Is there a way to avoid the second SELECT?
You could also alternatively use DISTINCT ON:
SELECT * FROM contracts c LEFT JOIN (
SELECT DISTINCT ON (cd.contract_id) cd.* FROM contract_descriptions cd
ORDER BY cd.contract_id, cd.date_description DESC
) d ON d.contract_id = c.contract_id
DISTINCT ON selects only one row per contract_id while the sort clause cd.date_description DESC ensures that it is always the last description.
Performance depends on many values (for example, table size). In any case, you should compare both approaches with EXPLAIN.
Your query looks okay to me. One typical way to join only n rows by some order from the other table is a lateral join:
SELECT *
FROM contracts c
CROSS JOIN LATERAL
(
SELECT *
FROM contract_descriptions cd
WHERE cd.contract_id = c.contract_id
ORDER BY cd.date_description DESC
FETCH FIRST 1 ROW ONLY
) cdlast;
I have the following subquery.
In the end i want to count for every agent for all this users the controllers.
So in the substring i count the controllers for all the agent his users and
then i want to sum them up.
The substring itself is running, however i get this error when i run the complete query
ERROR: missing FROM-clause entry for table "sub"
LINE 2: a.id as a_id, SUM(sub.c_count ) as c_count,
SELECT
a.id as a_id, SUM(sub.c_count ) AS c_count,
(
SELECT u.id, COUNT(c.user_id) AS c_amount
FROM users u
JOIN controllers c ON (c.user_id = u.id)
GROUP BY
u.id
)sub
from agents a;
You are getting this error because the subquery which you have aliased as sub returns not only multiple records, but also multiple values per record, but it appears in the SELECT list. Generally, only scalars (single values) or subqueries which return a single value can appear in the SELECT list. You have two options, you can either modify sub to return a single value, or you can try to join this subauery to the outer query. Given that you mentioned the subquery is supposed to do some aggregation for each user or agent, my guess is that joining is the answer. In the query below I join sub to the outer query on the agent ID matching the user ID from sub.
SELECT a.id AS a_id,
COALESCE(sub.c_amount, 0) AS c_count
FROM agents a
LEFT JOIN
(
SELECT u.id, COUNT(c.user_id) AS c_amount
FROM users u
INNER JOIN controllers c
ON c.user_id = u.id
GROUP BY u.id
) sub
ON a.id = sub.id
I have a nested select query that is returning the proper amount of rows. The query builds a recordset and compares it to a table and returns the records in the query that are not in the table.
I converted the select query to an update query. I am trying to populate the table with the rows returned from the query. When I run the update query it is returning with zero rows to update. I dont understand why because the select query is returning record and I am using the same code in the update query.
Thanks
Select Query: (This is returning several records)
Select *
From
(SELECT DISTINCT
ProductClass,SalProductClass.[Description],B.Branch,B.BranchDesc,B.Salesperson,B.Name,
CAST(0 AS FLOAT) AS Rate,'N' AS Split
FROM (SELECT SalBranch.Branch,SalBranch.[Description] AS BranchDesc,A.Salesperson,A.Name
FROM (SELECT DISTINCT
Salesperson,Name
FROM SalSalesperson
) A
CROSS JOIN SalBranch
) B
CROSS JOIN SalProductClass
) C
Left Outer Join RateComm On
RateComm.ProductClass = C.ProductClass and
RateComm.Branch = C.Branch And RateComm.Salesperson = C.Salesperson
Where RateComm.ProductClass is Null
Update Query: (This is returning zero records)
UPDATE RateComm
SET RateComm.ProductClass=C.ProductClass,RateComm.ProdClassDesc=C.ProdClassDesc,
RateComm.Branch=C.Branch,RateComm.BranchDesc=C.BranchDesc,RateComm.Salesperson=C.Salesperson,
RateComm.Name=C.Name,RateComm.Rate=C.Rate,RateComm.Split=C.Split
FROM (SELECT DISTINCT
ProductClass,SalProductClass.[Description] AS ProdClassDesc,B.Branch,B.BranchDesc,B.Salesperson,B.Name,
CAST(0 AS FLOAT) AS Rate,'N' AS Split
FROM (SELECT SalBranch.Branch,SalBranch.[Description] AS BranchDesc,A.Salesperson,A.Name
FROM (SELECT DISTINCT
Salesperson,Name
FROM SalSalesperson
) A
CROSS JOIN SalBranch
) B
CROSS JOIN SalProductClass
) C
LEFT OUTER JOIN RateComm ON C.ProductClass=RateComm.ProductClass AND
C.Salesperson=RateComm.Salesperson AND C.Branch=RateComm.Branch
WHERE RateComm.ProductClass IS NULL
It's difficult to update what doesn't exist. Have you tried an INSERT query instead?