How to skip the null values
Example Table Structure: Table Name : T1
ID A_Comments A_ts B_Comments B_ts C_Comments C_ts
1 Approved 20 Simple null fine null
1 Approved null Simple 10 fine null
1 Approved null Simple null fine 30
Expecting result:
ID A_Comments A_ts B_Comments B_ts C_Comments C_ts
1 Approved 20 Simple 10 fine 30
Use aggregation:
select id, max(a_comments) as a_commments, max(a_ts) as a_ts, . . .
from t1
group by id;
I am guessing that your table was created by an aggregation query with one too many columns in the group by.
Related
I have the following Table in Azure MSSQL:
ID,
Charge,
Payment
ID is the Primary Key and unique, Charge and Payment are Numeric.
ID charge payment
1 10 null
2 null 10
3 40 null
4 null 30
I want to do the following query:
select *,
SUM(charge)-sum(payment) OVER (order by id) AS Balance
from Table T
order by id asc
Which in the above data sample would look like this:
ID charge payment balance
1 10 null 10
2 null 10 0
3 40 null 40
4 null 30 10
However that query fails, complaining I need to do add a Group by clause, however if I run the following
select *,
SUM(charged) OVER (order by id) AS totalCharged
from table
order by id
That works fine - I feel like I've missed something obvious.
I should also note there are other columns that are in the final query but are omitted from here since they aren't relevant to the logic.
As it turns out, I was missing something obvious.
I changed the source query to use 0 instead of Null and then did the following:
select *,
SUM(charged - payment) OVER (order by id) AS balance
from table
order by id
So figured it out myself whilst thinking upon the porcelein throne.
i am trying to do a count on null values however , it is not able to count null values.
example of table :
Country Id Id_typ Info
Us 123 NULL Testing
Us 124 NULL Testing
Us 125 Bob testing
this is my script to count null values
select count(id_typ) from combined_a where id_typ= 'NULL' limit 1
i have tried
select count(id_typ) from table_a where id_typ is null limit 1
however when i have change the condition to search id_typ = bob, it was able to do a count . i am unsure on what did i do wrong , any advice?
You need is null and count(*):
select count(*)
from table_a
where id_typ is null;
limit 1 is redundant. A SQL query with an aggregation function and no group by always returns one row.
I'm looking to filter out rows in the database (PostgreSQL) if one of the values in the status column occurs. The idea is to sum the amount column if the unique reference only has a status equals to 1. The query should not SELECT the reference at all if it has also a status of 2 or any other status for that matter. status refers to the state of the transaction.
Current data table:
reference | amount | status
1 100 1
2 120 1
2 -120 2
3 200 1
3 -200 2
4 450 1
Result:
amount | status
550 1
I've simplified the data example but I think it gives a good idea of what I'm looking for.
I'm unsuccessful in selecting only references that only have status 1.
I've tried sub-queries, using the HAVING clause and other methods without success.
Thanks
Here's a way using not exists to sum all rows where the status is 1 and other rows with the same reference and a non 1 status do not exist.
select sum(amount) from mytable t1
where status = 1
and not exists (
select 1 from mytable t2
where t2.reference = t1.reference
and t2.status <> 1
)
SELECT SUM(amount)
FROM table
WHERE reference NOT IN (
SELECT reference
FROM table
WHERE status<>1
)
The subquery SELECTs all references that must be excluded, then the main query sums everything except them
select sum (amount) as amount
from (
select sum(amount) as amount
from t
group by reference
having not bool_or(status <> 1)
) s;
amount
--------
550
You could use windowed functions to count occurences of status different than 1 per each group:
SELECT SUM(amount) AS amount
FROM (SELECT *,COUNT(*) FILTER(WHERE status<>1) OVER(PARTITION BY reference) cnt
FROM tc) AS sub
WHERE cnt = 0;
Rextester Demo
I have a database with around 50 million entries showing the status of a device for a given day, simplified to the form:
id | status
-------------
1 | Off
1 | Off
1 | On
2 | Off
2 | Off
3 | Off
3 | Off
3 | On
...
such that each id is guaranteed to have at least 2 rows with an 'off' status, but doesn't have to have an 'on' status. I'm trying to get a list of only the ids that do not have an 'On' status. For example, in the above data set I'd want a query returned with only '2'
The current query is:
SELECT DISTINCT id FROM table
EXCEPT
SELECT DISTINCT id FROM table WHERE status <> 'Off'
Which seems to work, but it's having to iterate over the entire table twice which ends up taking ~10-12 minutes to run per query. Is there a simpler way to do this with only a single query?
You can use WHERE NOT EXISTS instead:
Select Distinct Id
From Table A
Where Not Exists
(
Select *
From Table B
Where A.Id = B.Id
And B.Status = 'On'
)
I would also recommend looking at the indexes on the Status column. 10-12 minutes to run is excessively long. Even with 50m records, with proper indexing, a query like this shouldn't take longer than a second.
To add an index to the column, you can run this (I'm assuming SQL Server, your syntax may vary):
Create NonClustered Index Ix_YourTable_Status On YourTable (Status Asc);
You can use conditional aggregation.
select id
from table
group by id
having count(case when status='On' then 1 end)=0
You can use the help of a SELF JOIN ..
SELECT DISTINCT A.Id
FROM Table A
LEFT JOIN Table B ON A.Id=B.Id
WHERE B.Status='On'
AND B.Id IS NULL
I am creating a file orginization system where you can add content items to multiple folders.
I am storing the data in a table that has a structure similar to the following:
ID TypeID ContentID FolderID
1 101 1001 1
2 101 1001 2
3 102 1002 3
4 103 1002 2
5 103 1002 1
6 104 1001 1
7 105 1005 2
I am trying to select the first record for each unique TypeID and ContentID pair. For the above table, I would want the results to be:
ID
1
3
4
6
7
As you can see, the pairs 101 1001 and 103 1002 were each added to two folders, yet I only want the record with the first folder they were added to.
When I try the following query, however, I only get result that have at least two entries with the same TypeID and ContentID:
select MIN(ID)
from table
group by TypeID, ContentID
results in
ID
1
4
If I change MIN(ID) to MAX(ID) I get the correct amount of results, yet I get the record with the last folder they were added to and not the first folder:
ID
2
3
5
6
7
Am I using GROUP BY or the MIN wrong? Is there another way that I can accomplish this task of selecting the first record of each TypeID ContentID pair?
MIN() and MAX() should return the same amount of rows. Changing the function should not change the number of rows returned in the query.
Is this query part of a larger query? From looking at the sample data provided, I would assume that this code is only a snippet from a larger action you are trying to do. Do you later try to join TypeID, ContentID or FolderID with the tables the IDs are referencing?
If yes, this error is likely being caused by another part of your query and not this select statement. If you are using joins or multi-level select statements, you can get different amount of results if the reference tables do not contain a record for all the foreign IDs.
Another suggestion, check to see if any of the values in your records are NULL. Although this should not affect the GROUP BY, I have sometime encountered strange behavior when dealing with NULL values.
Use ROW_NUMBER
WITH CTE AS
(SELECT ID,TypeID,ContentID,FolderID,
ROW_NUMBER() OVER (PARTITION BY TypeID,ContentID ORDER BY ID) as rn FROM t
)
SELECT ID FROM CTE WHERE rn=1
Use it with ORDER BY:
select *
from table
group by TypeID, ContentID
order by id
SQLFiddle: http://sqlfiddle.com/#!9/024016/12
Try with first ( id) instead of min(id)
select first(id)
from table
group by TypeID, ContentID
It works ?