Table:
column 1 column 2 column 3
2 two 3
5 five 8
3 three 10
8 eight 11
12 one 15
I want to create a new column column 4like below:
column 1 column 2 column 3 column 4
2 two 3 three
5 five 8 eight
3 three 10
8 eight 11
12 one 15
I want to map column 3 and column 1 and if there's a match column 4 takes values of column 2.
Example: Value 3 in column 3 is present in column 1, so column 4 will take corresponding column 3 value three.
Thanks!
This looks like a left join:
select t.*, tt.column2 as column4
from table1 t left join
table1 tt
on t.column3 = tt.column1;
EDIT:
If you want to set the value, you can use update:
update table1 t
set column4 = (select tt.column2 from table1 tt where t.column3 = tt.column1)
where exists (select 1 from table1 tt where t.column3 = tt.column1);
However, this seems silly. You can easily get the value in the table using an explicit join or hiding the logic in a view.
Related
The table to find which rows contains same value on two different columns for 2 rows. Here is a small sample rows among 2k+ rows.
id left right
1 3 4
2 4 1
3 1 9
4 2 6
5 2 5
6 9 8
7 0 7
In the above case, I need to get row 1,2,3,6 as it contains 4 on two rows of two different columns i.e (id=1&2),1 on two rows of two different columns(id=1&3) and 9 on two rows of two different columns(id=3&6)
My thoughts:
I did thought many things for example cross join on left and right column, group by and count etc.
with Final as (With OuterTable as (WITH Alias AS (SELECT id as left_id , left FROM Test)
SELECT DISTINCT id, left_id FROM Alias
INNER JOIN Test ON Alias.left = Test.right)
SELECT id from OuterTable
UNION ALL
SELECT left_id from OuterTable)
SELECT DISTINCT * from Final;
It's messy, but it works.
You can do it with EXISTS:
SELECT t1.*
FROM tablename t1
WHERE EXISTS (
SELECT 1 FROM tablename t2
WHERE t1.id <> t2.id AND (t2.left = t1.right OR t1.left = t2.right)
)
See the demo.
Results:
id
left
right
1
3
4
2
4
1
3
1
9
6
9
8
Lets say I have the following table
a b c
-----------
1 1 5
1 2 3
4 1 2
1 2 4
4 2 10
And I want to delete all rows where none of the first n rows has the same value in a and b as that row.
So for example the resulting tables for various n's would be
n = 1
a b c
-----------
1 1 5
// No row other than the first has a 1 in a, and a 1 in b
n = 2
a b c
-----------
1 1 5
1 2 3
1 2 4
// The fourth row has the same values in a and b as the second, so it is not deleted. The first 2 rows of course match themselves so are not deleted
n = 3
a b c
-----------
1 1 5
1 2 3
4 1 2
1 2 4
// The fourth row has the same values in a and b as the second, so it is not deleted. The first 3 rows of course match themselves so are not deleted
n = 4
a b c
-----------
1 1 5
1 2 3
4 1 2
1 2 4
// The first 4 rows of course match themselves so are not deleted. The fifth row does not have the same value in both a and b as any of the first 4 rows, so is deleted.
I've been trying to work out how to do this using a not in or a not exists, but since I'm interested in two columns matching not just 1 or the whole record, I'm struggling.
Since you are not defining a specific order, the result is not completely defined, but depends on arbitrary choices of implementation regarding which rows are computed first in the limit clause. A different SQLite version for example may give you a different result. With that being said, I believe that you want the following query:
select t1.* from table1 t1,
(select distinct t2.a, t2.b from table1 t2 limit N) tabledist
where t1.a=tabledist.a and t1.b=tabledist.b;
where you should replace N with the desired number of rows
EDIT: So, to delete directly from the existing table you need something like:
with toremove(a, b, c) as
(select * from table1 tt
EXCEPT select t1.* from table1 t1,
(select distinct t2.a, t2.b from table1 t2 limit N) tabledist
where t1.a=tabledist.a and t1.b=tabledist.b)
delete from table1 where exists
(select * from toremove
where table1.a=toremove.a and table1.b=toremove.b and table1.c=toremove.c);
I have an input:
id
1
2
3
4
5
6
7
8
9
10
I want get even and odd columns separately by columns in specified output like this
id col
1 2
3 4
5 6
7 8
9 10
here id and col are separate columns id contains the odd number and col contains the even number for specified input
SELECT MIN(id) as id, MAX(id) as col
FROM YourTable
GROUP BY FLOOR((id+1)/2)
For IDs 1 and 2, (id+1)/2 are 2/2 = 1 and 3/2 = 1.5, respectively, and FLOOR then returns 1 for both of them. Similarly, for 3 and 4, this is 2, and so on. So it groups all the input rows into pairs based on this formula. Then it uses MIN and MAX within each group to get the lower and higher IDs of the pairs.
Joined the table on itself
select *
from yourTable tA
left join yourTable tb on tA.id = (tB.id - 1)
where tA.id % 2 <> 0
If you use SQL you can try:
SELECT CASE WHEN column % 2 = 1
THEN column
ELSE null
END AS odds,
CASE WHEN column % 2 = 2
THEN column
ELSE null
END AS even
FROM yourtable
but not exactl as you ask
To show odd:
Select * from MEN where (RowID % 2) = 1
To show even:
Select * from MEN where (RowID % 2) = 0
Now, just join those two result sets and that's it.
Source
By using SQlite, I'd like to get all rows that show in a specific column only one single distinct value. Like from following table:
A B
1 2
2 1
3 2
4 3
5 1
6 1
7 2
8 4
9 2
Here I'd like to get only row Nr. 4 an 8 as there values (3 and 4) occur only once in the entire column.
You could use a query like this:
SELECT *
FROM mytable
WHERE B IN (SELECT B FROM mytable GROUP BY B HAVING COUNT(DISTINCT A)=1)
Please see fiddle here.
Subquery will return all B values that are present only once (you could also use HAVING COUNT(*)=1 in this case), the outer query will return all rows where B is returned by the subquery.
I don't know what in the world is the best way to go about this. I have a very large array of columns, each one with 1-25 rows associated with it. I need to be able to combine all into one large column, skipping blanks if at all possible. Is this something that Access can do?
a b c d e f g h
3 0 1 1 1 1 1 5
3 5 6 8 8 3 5
1 1 2 2 1 5
4 4 2 1 1 5
1 5
there are no blanks within each column, but each column has a different number of numbers in it. they need to be added from left to right so a,b, c, d, e, f. And the 0 from be needs to be in the first blank cell after the second 3 in A. And the first 5 in H needs to be directly after the 1 in g, with no blanks.
So you want a result like:
3
3
0
5
1
4
1
6
1
4
etc?
Here is how I would approach the problem. Insert your array into a work table with an autonumber column (important to retain the order the data is in, databases do not guarnatee an order unless you can give them something to sort on) called id
as well as the array columns.
Create a final table with an autonumber column (see above note on why you need an automnumber) and the column you want as you final table.
Run a separate insert statment for each column in your work table and run them in the order you want the data.
so the inserts would look something like:
insert table2 (colA)
select columnA from table1 order by id
insert table2 (colA)
select columnB from table1 order by id
insert table2 (colA)
select columnC from table1 order by id
Now when you do select columnA from table2 order by id you should have the results you need.