I would like to perform the equivalent of SELECT TOP 1 ... query in db2 / dashDB:
SELECT TOP 1 * FROM customers
How can I achieve this?
You can achieve this query using the FETCH FIRST x ROWS ONLY statement, E.g.
SELECT * FROM customers FETCH FIRST 1 ROWS ONLY
Another way on dashDB, and more easy for my opinion is to use the 'limit n', E.g.
SELECT * FROM customers LIMIT 1
Related
I am trying to add a new column to a power query result that is the result of subtracting one column from another. according to the power bi documentation basic arithmetic is supported with query folding but for some reason it is showing a failure to query fold. I also tried simply adding a column populated with the number 1 and it still was not working. Is there some trick to getting query folding a new column to work on snowflake?
If the computation is made based only on data from source, then it could be computed during table import as SQL Statement:
SELECT col1, col2, col1 + col2 AS computed_total
FROM my_table_name
EDIT:
The problem with this solution is that native SQL statement for snowflake is only supported on PBI desktop and I want to have this stored in a dataflow (so pbi web client) for reusability and other reasons.
Option 1:
Create a view istead of table at source:
CREATE OR REPLACE VIEW my_view
AS
SELECT col1, col2, col1 + col2 AS computed_total
FROM my_table_name;
Option 2:
Add computed column to the table:
ALTER TABLE my_table_name
ADD COLUMN computed_total NUMBER(38,4) AS (col1 + col2);
I am working on Informatica Cloud Data
Integraion.I have 2 tables- Tab1 and Tab2.The joining column is id.I want to find all records in Tab1 that do not exist in Tab2.What transformations can I use to achieve this?
Tab1
id name
1 n1
2 n2
3 n3
Tab2
id
1
5
6
I want to get records with id 2 and 3 from tab1 as they do not exist in tab2
You can use database source qualifier overwrite sql
Select * from table1 where id not in ( select id from table2)
Or else you can use informatica like below.
Do a lookup on table2, on join condition on id.
In exp transformation, create a flag
out_flag= iif(isnull (:lkp(id)),'pass','fail')
Put a filter next and keep the condition as out_flag= 'pass'
Whole map should be like this
Lkp
|
Sq --exp|-----> fil---tgt
I'm currently running QuestDB 6.1.2 on linux. How do I get the row with maximum value from a table? I have tried the following on a test table with around 5 million rows:
select * from table where cast(timestamp as symbol) in (select cast(max(timestamp) as symbol) from table );
select * from table inner join (select max(timestamp) mm from table ) on timestamp >= mm
select * from table where timestamp = max(timestamp)
select * from table where timestamp = (select max(timestamp) from table )
where 1 is correct but runs in ~5s, 2 is correct and runs in ~500ms but looks unnecessarily verbose for a query, 3 compiles but returns an empty table, and 4 is incorrect syntax although that's how sql usually does it
select * from table limit -1 works. QuestDB returns rows sorted by timestamp as default, and limit -1 takes the last row, which happens to be the row with the greatest timestamp. To be explicit about ordering by timestamp, select * from table order by timestamp limit -1 could be used instead. This query runs in around 300-400ms on the same table.
As a side note, the third query using timestamp=max(timestamp) doesn't work yet since QuestDB does not support subqueries in where yet (questDB 6.1.2).
I'm creating paging output from data in QuestDB table and want to take 100 rows after X pages of 100 rows. In Postgres it would be something like
select * from tbl
OFFSET 200
LIMIT 100
I see LIMIT but cannot find OFFSET equivalent in QuestDB SQL, is it supported?
Thanks to #basha04 the equivalent query is
select * from tbl
LIMIT 200,300
I need to update a second table with the results of this query:
SELECT Tag, battery, Wearlevel, SensorTime
FROM (
SELECT m.* , ROW_NUMBER() OVER (PARTITION BY TAG ORDER BY SensorTime DESC) AS rn
FROM [dbo].[TELE] m
) m2
where m2.rn = 1;
But. I had a hard time fixing the SET without messing it up. I want to have a table which has all data from last date of each TAG without duplicates.
Below code maybe you want.
UPDATE
Table_A
SET
Table_A.Primarykey = 'ss'+Table_B.Primarykey,
Table_A.AddTime = 'jason_'+Table_B.AddTime
FROM
Test AS Table_A
INNER JOIN UsersInfo AS Table_B
ON Table_A.id = Table_B.id
WHERE
Table_A.Primarykey = '559713e6-0d85-4fe7-87a4-e9ceb22abdcf'
For more details, you also can refer below posts and blogs.
1. How do I UPDATE from a SELECT in SQL Server?
2. How to UPDATE from SELECT in SQL Server