excluding rows from resultset in postgres - postgresql

This is my result set
i am returning this result set on the base of refid using WHERE refid IN.
Over here, i need to apply a logic without any kind of programming (means SQL query only).
if in result set, i am getting period for particular refid then other rows with the same refid must not returned.
for example, 2667105 having period then myid = 612084598 must not get returned in result set.
according to me this can be achieved using CASE but i have no idea how to use it, i mean that i don't know should i use the CASE statement in SELECT statement or WHERE clause...
EDIT:
This is how it suppose to work,
myid = 612084598 is the default row for refid = 2667105 but if specifically wants the refid for period = 6 then it must return all rows except myid = 612084598
but if i am looking for period = 12, for this period no specific refid present in database.. so for this it must return all rows except first one.. means all rows with the refid which is default one..

Not very clear definition of the problem, but try this:
with cte as (
select
*,
first_value(period) over(partition by refid order by myid) as fv
from test
)
select
myid, refid, period
from cte
where period is not null or fv is null
sql fiddle demo

Related

more than one row returned by a subquery used as an expression problem

I am trying to update a column in one database with a query:
Here the query
and this is the output i think it is impossible to asign a query to a field but what is the solution for that plz.
enter image description here
= can be used when we are pretty sure that the subquery returns only 1 value.
When we are not sure whether subquery returns more than 1 value, we will have to use IN to accommodate all values or simply use TOP 1 to limit the equality matching to one value:
UPDATE mascir_fiche SET partner = (SELECT TOP 1 id FROM hr_employee WHERE parent_id IN (SELECT id FROM hr_employee));
With Limit:
UPDATE mascir_fiche SET artner = (SELECT id FROM hr_employee WHERE parent_id IN (SELECT id FROM hr_employee) limit 1);

Single Value Expression in When Then Aggregate Function TSQL

I am trying to map a certain value of a column based on its count on another table. If the count of [Location] i.e a column of IMPORT.DATA_SCRAP table in each row. For now for location static value i.e Utah and Kathmandu is supplied for test purpose only is equal to 1, then only i need to get the result in the select statement i.e only single value expression must be returned but here n rows of table with value is returned.
For. eg. In the below query,total rows of IMPORT.DATA_SCRAP gets returned, i only need the single first row value in my case.
I came to know whether cursor or CTE will acheive my result but i am unable to figure it out.
Here,
select
case
when
((SELECT COUNT(stateName) FROM Location.tblState where stateName = 'Utah')=1)
then (select stateName, CountryName from Location.tblState where stateName= 'Utah')
end as nameof
from IMPORT.DATA_SCRAP
The relation between country, state, city is as below:
select
case
when
((SELECT COUNT(cityName) FROM Location.tblCity where cityName = 'Kathmandu')=1)
then (select ct.countryName from Location.tblCity c
inner join Location.tblState s
on c.stateID = s.StateID
inner join Location.tblCountry ct
on ct.countryId = s.CountryId
where c.cityName = 'Kathmandu'
)
end as nameof
from IMPORT.DATA_SCRAP
How can i return only a single value expresion despite of multiple nmax rows of IMPORT.DATA_SCRAP row in the result.
If i comment out the -- from IMPORT.DATA_SCRAP in the above query i would get the desired single result expression in my case, but unable how can i acheive it in other ways or suggest me the appropriate way to do these types of situation.

EXISTS in filter returning too many values

I need to write a query that uses EXISTS, rather than IN, so that it will run fast. The filter is being fed so many parameter values that EXISTS seems like the only option. The difference is between a 20+ minute query and a 5 second query.
This is the query I have:
SELECT DISTINCT d.GROUP_NAME
FROM [EMPLOYEE] e JOIN [DATA_FACT] d ON (e.KEY = d.KEY)
WHERE d.DATE BETWEEN #Start and #End
AND EXISTS
(
select '1234567' -- #ID
)
AND e.Location IN (#Location)
ORDER BY d.GROUP_NAME ASC
The problem is that it is returning too many records. Based on the values I'm passing to filter on, I should get 1 row back but instead I am getting 28.
If I remove the EXISTS and add the following then I get the 1 record I need:
AND e.ID IN ('1234567')
Is there a way to fix the query to work with EXISTS so that I get the correct results?
This is essentially what you want if you are going to try to use exists to filter your data_fact table by parameters in your employee table. Not sure how much it's going to improve your performance though when you throw a massive number of employee IDs at it.
SELECT
d.GROUP_NAME
FROM [DATA_FACT] AS d
WHERE d.DATE BETWEEN #Start and #End
AND EXISTS
(
select 1
from EMPLOYEE AS e
WHERE d.[KEY] = e.[KEY]
AND e.[Location] IN (#Location)
AND e.ID IN ('1234567')
)
ORDER BY d.GROUP_NAME ASC

SQL Server - How Do I Create Increments in a Query

First off, I'm using SQL Server 2008 R2
I am moving data from one source to another. In this particular case there is a field called SiteID. In the source it's not a required field, but in the destination it is. So it was my thought, when the SiteID from the source is NULL, to sort of create a SiteID "on the fly" during the query of the source data. Something like a combination of the state plus the first 8 characters of a description field plus a ten digit number incremented.
At first I thought it might be easy to use a combination of date/time + nanoseconds but it turns out that several records can be retrieved within a nanosecond leading to duplicate SiteIDs.
My second idea was to create a table that contained an identity field plus a function that would add a record to increment the identity field and then return it (the function would also delete all records where the identity field is less than the latest saving space). Unfortunately after I got it written, when trying to "CREATE" the function I got a notice that INSERTs are not allowed in functions.
I could (and did) convert it to a stored procedure, but stored procedures are not allowed in select queries.
So now I'm stuck.
Is there any way to accomplish what I'm trying to do?
This script may take time to execute depending on the data present in the table, so first execute on a small sample dataset.
DECLARE #TotalMissingSiteID INT = 0,
#Counter INT = 0,
#NewID BIGINT;
DECLARE #NewSiteIDs TABLE
(
SiteID BIGINT-- Check the datatype
);
SELECT #TotalMissingSiteID = COUNT(*)
FROM SourceTable
WHERE SiteID IS NULL;
WHILE(#Counter < #TotalMissingSiteID )
BEGIN
WHILE(1 = 1)
BEGIN
SELECT #NewID = RAND()* 1000000000000000;-- Add your formula to generate new SiteIDs here
-- To check if the generated SiteID is already present in the table
IF ( ISNULL(( SELECT 1
FROM SourceTable
WHERE SiteID = #NewID),0) = 0 )
BREAK;
END
INSERT INTO #NewSiteIDs (SiteID)
VALUES (#NewID);
SET #Counter = #Counter + 1;
END
INSERT INTO DestinationTable (SiteID)-- Add the extra columns here
SELECT ISNULL(MainTable.SiteID,NewIDs.SiteID) SiteID
FROM (
SELECT SiteID,-- Add the extra columns here
ROW_NUMBER() OVER(PARTITION BY SiteID
ORDER BY SiteID) SerialNumber
FROM SourceTable
) MainTable
LEFT JOIN ( SELECT SiteID,
ROW_NUMBER() OVER(ORDER BY SiteID) SerialNumber
FROM #NewSiteIDs
) NewIDs
ON MainTable.SiteID IS NULL
AND MainTable.SerialNumber = NewIDs.SerialNumber

PostgreSQL and pl/pgsql SYNTAX to update fields based on SELECT and FUNCTION (while loop, DISTINCT COUNT)

I have a large database, that I want to do some logic to update new fields.
The primary key is id for the table harvard_assignees
The LOGIC GOES LIKE THIS
Select all of the records based on id
For each record (WHILE), if (state is NOT NULL && country is NULL), update country_out = "US" ELSE update country_out=country
I see step 1 as a PostgreSQL query and step 2 as a function. Just trying to figure out the easiest way to implement natively with the exact syntax.
====
The second function is a little more interesting, requiring (I believe) DISTINCT:
Find all DISTINCT foreign_keys (a bivariate key of pat_type,patent)
Count Records that contain that value (e.g., n=3 records have fkey "D","388585")
Update those 3 records to identify percent as 1/n (e.g., UPDATE 3 records, set percent = 1/3)
For the first one:
UPDATE
harvard_assignees
SET
country_out = (CASE
WHEN (state is NOT NULL AND country is NULL) THEN 'US'
ELSE country
END);
At first it had condition "id = ..." but I removed that because I believe you actually want to update all records.
And for the second one:
UPDATE
example_table
SET
percent = (SELECT 1/cnt FROM (SELECT count(*) AS cnt FROM example_table AS x WHERE x.fn_key_1 = example_table.fn_key_1 AND x.fn_key_2 = example_table.fn_key_2) AS tmp WHERE cnt > 0)
That one will be kind of slow though.
I'm thinking on a solution based on window functions, you may want to explore those too.