I have got one table (Table1) with some columns filled by data and one empty column. There is another table (Table2) with one column with data. There is no foreign key or any link to that tables just row numbers are equal. I want update empty column of Table1 by data from column of Table2 row by row (row1 from table2 to row1 from table1. Is any way to do it but not using export to file? Is possible to do that using while loop?
If I understand correctly, you can use row_number():
with toupdate as (
select t1.*, row_number() over (order by (select NULL)) as seqnum
from table1 t1
)
update toupdate
set col = t2.col
from (select t2.*, row_number() over (order by (select NULL)) as seqnum
from table2 t2
) t2
where t2.seqnum = t1.seqnum;
Add rownumbers like this and join them:
WITH CTE_TableA AS(
SELECT ColA, ROW_NUMBER() OVER (PARTITION BY ColA ORDER BY ColA) AS RowA
FROM TableA)
,CTE_TableB AS
SELECT ColB, ROW_NUMBER() OVER (PARTITION BY ColB ORDER BY ColB) AS RowB
FROM TableB
SELECT * FROM CTE_TableA AS A
INNER JOIN CTE_TableB AS B ON A.RowA = B.RowB
Related
There are values in my data set. there are 3 columns.
column 1 has values 1,1,3,4,5,5,6,7,7,7,7. I need to sort the column and then apply average.
1,1 means two rows with index 1 and 1. i need to average values in rest of the columns i.e column 2 and column 3 for each row.
similarly for data in 5,5 and so on. able to sort but cannot manage the average problem..
The ROW_NUMBER() should do the sorting for you and (col1+col2+col3)/3 should make it average for you. For nullable columns you will need to do some changes to the code.
SELECT t1.rownumber, (t1.col1 + t2.col2 + t3.col3)/3 as "AVG"
FROM (SELECT ROW_NUMBER() OVER(ORDER BY col1 DESC) AS rownumber, col1 FROM MyTable) t1
INNER JOIN (SELECT ROW_NUMBER() OVER(ORDER BY col2 ASC) AS rownumber, col2 FROM MyTable) as t2 on t1.rownumber = t2.rownumber
INNER JOIN (SELECT ROW_NUMBER() OVER(ORDER BY col3 ASC) AS rownumber, col3 FROM MyTable) as t3 on t1.rownumber = t3.rownumber
Your question sounds like a convoluted way of describing aggregation. Is this what you want?
select col1, avg(col2), avg(col3)
from t
group by col1;
If you want the average on each row, then use window functions:
select col1,
avg(col2) over (partition by (col1),
avg(col3) over (partition by (col1)
from t;
I have a table in my Postgres database where I forgot to insert a unique index. because of that index that i have now duplicated values. How to remove the duplicated values? I want to add a unique index on the fields translationset_Id and key.
I think you are asking for this:
DELETE FROM tablename
WHERE id IN (SELECT id
FROM (SELECT id,
ROW_NUMBER() OVER (partition BY column1, column2, column3 ORDER BY id) AS rnum
FROM tablename) t
WHERE t.rnum > 1);
It appears that you only want to delete records which are duplicate with regard to the translationset_id column. In this case, we can use Postgres' row number functionality to discern between duplicate rows, and then to delete those duplicates.
WITH cte AS
(
SELECT t.*, ROW_NUMBER() OVER (PARTITION BY translationset_id, key) AS rnum
FROM yourTable t
)
DELETE FROM yourTable
WHERE translationset_id IN (SELECT translationset_id FROM cte WHERE rnum > 1)
I think the most efficient way to do this is below.
DELETE FROM
table_name a
USING table_name b
WHERE
a.id < b.id and
a.same_column = b.same_column;
delete from mytable
where exists (select 1
from mytable t2
where t2.name = mytable.name and
t2.address = mytable.address and
t2.zip = mytable.zip and
t2.ctid > mytable.ctid
);
What I am trying to accomplish:
Dataset 1
Name1
Name2
Name3
Dataset 2
Number1
Number2
Number3
will become 2 columns:
dataset1 dataset2
Name1 Number1
Name2 Number2
Name3 Number3
My datasets 1 & 2 will always have equal rows.
Which name linked to which number I don't care as long as two names are not linked to the same number and vice versa.
How can I solve this with SQL / SQL Server ?
If you don't want to add an identity column to the tables, you can use the ROW_NUMBER() function like this:
SELECT
T1.Col1,
T2.Col1
FROM
(SELECT Col1, ROW_NUMBER() OVER (ORDER BY Col1) AS N FROM Table1) T1
INNER JOIN
(SELECT Col1, ROW_NUMBER() OVER (ORDER BY Col1) AS N FROM Table2) T2
ON T1.N = T2.N
Here, replace Table1 and Table2 with the name of your tables, and replace Col1 with the name of the column (or columns) that you want to output from the two tables.
Add identity columns to both the tables and perform join on basis of these column
ALTER TABLE Table1
ADD ID INT IDENTITY(1,1) NOT NULL
ALTER TABLE Table2
ADD ID INT IDENTITY(1,1) NOT NULL
SELECT Table1.dataset1col , Table2.dataset2Col
From Table1 INNER JOIN Table2
ON Table1.ID = Table2.ID
This may work for you :
;WITH cte1 (name, rn)
AS (SELECT Name,
row_number()
OVER(
ORDER BY Name) rn
FROM Dataset1),
cte2 (Number, rn)
AS (SELECT Number,
row_number()
OVER(
ORDER BY Number) rn
FROM Dataset2)
SELECT name,
Number
FROM cte1
JOIN cte2
ON cte1.rn = cte2.rn
WITH Table1 AS
(
SELECT ROW_NUMBER() OVER (PARTITION BY ID ORDER BY Dataset1) as Rnk,Dataset1
FROM TA1
)
With Table2 AS
(
SELECT ROW_NUMBER() OVER (PARTITION BY ID ORDER BY Dataset2) as Rnk, Dataset2
FROM TA2
)
Select Table.Dataset1 as 'DataSet1', Table2.DataSet2 as 'DataSet2'
From Table1
inner join Table2 on Table1.Rnk = Table2.Rnk
Because you haven't added table name so I considered it as TA1 and TA2.
Another way of writing the query is:
select row_number() over (order by Names asc) as rownum,
Names
into #Temp1
from NameTable
select row_number() over (order by Numbers asc) as rownum,
Numbers
into #Temp2
from NumberTable
select Names, Numbers
from #Temp1
inner join #Temp2 on #Temp1.rownum = #Temp2.rownum
Demo
There are 3 possible solutions to this.
First: Use following trick (Warning: Use this in case of small datasets)
SELECT DISTINCT tbl1.col1, tbl2.col2
FROM
(SELECT FirstName AS col1, ROW_NUMBER() OVER (ORDER BY FirstName) Number FROM dbo.User) tbl1
INNER JOIN
(SELECT LastName AS col2, ROW_NUMBER() OVER (ORDER BY LastName) Number FROM dbo.User) tbl2
ON tbl1.Number = tbl2.Number
Second: Use variable tables to store result temporarily. This solution is for relatively large datasets. (approx records to 100s)
Third:
Use identitfy field in both tables as already mentioned by mmhasannn. But i will prefer this method least, as we need to modify our DB structure.
RECOMMENDED: Use variable tables approach
I have a table A with two columns named B and C as following:
('W1','F2')
('W1','F7')
('W2','F1')
('W2','F6')
('W2','F8')
('W4','F7')
('W6','F2')
('W6','F15')
('W7','F1')
('W7','F4')
('W7','F17')
('W8','F13')
How can I find which one in the B column appears with the most time using sql in oracle? (In this case, it's W2 and W7). Thank you!
Use a subquery to calculate the number of items in columC for each value in columnB and rank() the results of the subquery based on that count. Then in your main select return just the values of columnB where the rank of the rows returned by the subquery is 1:
SELECT ColB
FROM (
SELECT ColB,
Count(ColC),
rank() over (ORDER BY Count(ColC) DESC) AS rnk
FROM yourTable
GROUP BY ColB)
WHERE rnk = 1
Here's a sql fiddle: http://sqlfiddle.com/#!4/fa6bd/2
/*
C2 REFERS TO THE COLUMN B
T1 Refers to an alias
*/
WITH T1 AS
(
SELECT C2,COUNT(*) AS COUNT
FROM YOURTABLE
GROUP BY C2
)
SELECT C2,COUNT FROM T1 WHERE COUNT=(SELECT MAX(COUNT) FROM T1 )
;
Select ColB, Count(*)
FROM yourTable
GROUP BY ColB
ORDER BY count(*) desc
Table Essentially looks like:
Serial-ID, ID, Date, Data, Data, Data, etc.
There can be Multiple Rows for the Same ID. I'd like to create a view of this table to be used in Reports that only shows the most recent entry for each ID. It should show all of the columns.
Can someone help me with the SQL select? thanks.
There's about 5 different ways to do this, but here's one:
SELECT *
FROM yourTable AS T1
WHERE NOT EXISTS(
SELECT *
FROM yourTable AS T2
WHERE T2.ID = T1.ID AND T2.Date > T1.Date
)
And here's another:
SELECT T1.*
FROM yourTable AS T1
LEFT JOIN yourTable AS T2 ON
(
T2.ID = T1.ID
AND T2.Date > T1.Date
)
WHERE T2.ID IS NULL
One more:
WITH T AS (
SELECT *, ROW_NUMBER() OVER(PARTITION BY ID ORDER BY Date DESC) AS rn
FROM yourTable
)
SELECT * FROM T WHERE rn = 1
Ok, i'm getting carried away, here's the last one I'll post(for now):
WITH T AS (
SELECT ID, MAX(Date) AS latest_date
FROM yourTable
GROUP BY ID
)
SELECT yourTable.*
FROM yourTable
JOIN T ON T.ID = yourTable.ID AND T.latest_date = yourTable.Date
I would use DISTINCT ON
CREATE VIEW your_view AS
SELECT DISTINCT ON (id) *
FROM your_table a
ORDER BY id, date DESC;
This works because distinct on suppresses rows with duplicates of the expression in parentheses. DESC in order by means the one that normally sorts last will be first, and therefor be the one that shows in the result.
https://www.postgresql.org/docs/10/static/sql-select.html#SQL-DISTINCT
This seems like a good use for correlated subqueries:
CREATE VIEW your_view AS
SELECT *
FROM your_table a
WHERE date = (
SELECT MAX(date)
FROM your_table b
WHERE b.id = a.id
)
Your date column would need to uniquely identify each row (like a TIMESTAMP type).