I have the following table, TableA, with data:
ID ColA
0 10
1 null
2 20
I have another table, TableB, with the following data.
ID ColB ColC
1 30 80
1 40 70
3 50 100
I need to select rows in TableA but when ColA in the row is null, I want to retrieve the value of ColB in TableB (if one exists) and use it in place of ColA. If no value in ColB exists, then the value of ColA in the result should be null. The join is done on TableA.ID and TableB.ID. TableB can have multiple rows where the ID column repeats. TableB.ID and TableB.ColC together make a row unique. So my result should look like this if ColC is limited to the value of 70:
ID ColA
0 10
1 40
2 20
Not sure how to do this. Thanks for your help!
select a.ID, COALESCE(a.ColA, b.ColB) as 'ColA'
from TableA a
left join TableB b on a.ID = b.ID and b.ColC = 70
This seems to do what you want if I have correctly interpreted your question:
SELECT a.ID,
ISNULL(a.ColA, b.ColB) ColA
FROM TableA a
LEFT JOIN
TableB b
ON a.ID = b.ID
AND b.ColC = 70
I have literally "limited to the value of 70" in ColC as you stated.
sounds like you're looking for a case statement. try case when TableA.Value is null then TableB.Value end
SQL Case Statements
Related
I have large table table_A that has all the records from a smaller table table_B. I want to join these tables to find only those records from table_A that do not match with table_B
Example:
Table_A has
1
2
3
4
5
Table_B has
2
3
4
I need the result to show:
result:
1
5
There are different possibilities, but I would use the NOT EXISTS. For e.g.:
Select *
FROM Table_A AS ta
WHERE NOT EXISTS (
SELECT 1
FROM Table_B AS tb
WHERE tb.Id = ta.Id
)
Hope this helps!
You can use the ff. method in order to achieve this.
SELECT
A.Value
FROM Table_A as A
LEFT JOIN Table_B as B
ON A.Value = B.Value
WHERE B.Value IS NULL
I have two table:
Table1 is:
ID fname lname
---------------------
11 p1 p2
22 a1 a2
Table2 is:
ID fk_id field1 field2
------------------------------
1 11 2 3
2 22 5 4
and I have this statement in sqlite:
select * from Table1
where Table1.id=(select fk_id
from Table2
where (select sum([field1]-[field2])
from Table2 GROUP BY [fk_id]) > 0)
I expect that this query return all rows of Table1 but it return just one row!
why?!
I can't understand this!
It would help if there was the result.
So I guess because for table 11
sum(2 - 3) = -1
which fails for
select fk_id
from Table2
where (select sum([field1]-[field2])
from Table2 GROUP BY [fk_id]) > 0
So you only got 22 as your result.
You probably need a abs(sum([field1]-[field2]) then.
I have a query
SELECT id_anything FROM table1 JOIN table2 USING (id_tables)
Now, i have a situation which is:
If that join returns two rows from table2 i want to show the id_anything from table1 (1 row only)
and if the join from table2 returns 1 row, i want to show id_anything from table2.
Ps: id_anything from table 2 returns different values
Example data:
table1
id_tables | id_anything
1 | 1
table2
id_tables | id_anything
1 | 10
1 | 100
Return expected: 1
First, get the value you may want to return and the basis for deciding which to return together into one row.
SELECT table1.id_tables, table1.id_anything AS table1_id, MIN(table2.id_anything) AS table2_id, COUNT(*)
FROM table1 JOIN table2 USING (id_tables)
GROUP BY table1.id_tables, table1.id_anything
The aggregate function you use doesn't really matter since you'll only be using the value if there is only one.
You can then pick the relevant value:
WITH join_summary AS (
SELECT table1.id_tables, table1.id_anything AS table1_id, MIN(table2.id_anything) AS table2_id, COUNT(*) AS match_count
FROM table1 JOIN table2 USING (id_tables)
GROUP BY table1.id_tables, table1.id_anything
)
SELECT id_tables, CASE WHEN (match_count > 1) THEN table1_id ELSE table2_id END AS id_anything
FROM join_summary
I have a table segnature describing an item with a varchar field deno and a numeric field ord. A foreign key fk_collection tells which collection the row is part of.
I want to update field ord so that it contains the ordinal of that row per each collection, sorted by field deno.
E.g. if I have something like
[deno] ord [fk_collection]
abc 10
aab 10
bcd 10
zxc 20
vbn 20
Then I want a result like
[deno] ord [fk_collection]
abc 1 10
aab 0 10
bcd 2 10
zxc 1 20
vbn 0 20
I tried with something like
update segnature s1 set ord = (select count(*)
from segnature s2
where s1.fk_collection=s2.fk_collection and s2.deno<s1.deno
)
but query is really slow: 150 collections per about 30000 items are updated in 10 minutes about.
Any suggestion to speed up the process?
Thank you!
You can use a window function to generate the "ordinal" number:
with numbered as (
select deno, fk_collection,
row_number() over (partition by fk_collection order by deno) as rn,
ctid as id
from segnature
)
update segnature
set ord = n.rn
from numbered n
where n.id = segnature.ctid;
This uses the internal column ctid to uniquely identify each rows. The ctid comparison is quite slow, so if you have a real primary (or unique) key in that table, use that column instead.
Alternatively without the common table expression:
update segnature
set ord = n.rn
from (
select deno, fk_collection,
row_number() over (partition by fk_collection order by deno) as rn,
ctid as id
from segnature
) as n
where n.id = segnature.ctid;
SQLFiddle example: http://sqlfiddle.com/#!15/e997f/1
My table is like
ID FName LName Date(mm/dd/yy) Sequence Value
101 A B 1/10/2010 1 10
101 A B 1/10/2010 2 20
101 X Y 1/2/2010 1 15
101 Z X 1/3/2010 5 10
102 A B 1/10/2010 2 10
102 X Y 1/2/2010 1 15
102 Z X 1/3/2010 5 10
I need a query that should return 2 records
101 A B 1/10/2010 2 20
102 A B 1/10/2010 2 10
that is max of date and max of sequence group by id.
Could anyone assist on this.
-----------------------
-- get me my rows...
-----------------------
select * from myTable t
-----------------------
-- limiting them...
-----------------------
inner join
----------------------------------
-- ...by joining to a subselection
----------------------------------
(select m.id, m.date, max(m.sequence) as max_seq from myTable m inner join
----------------------------------------------------
-- first group on id and date to get max-date-per-id
----------------------------------------------------
(select id, max(date) as date from myTable group by id) y
on m.id = y.id and m.date = y.date
group by id) x
on t.id = x.id
and t.sequence = x.max_seq
Would be a simple solution, which does not take account of ties, nor of rows where sequence is NULL.
EDIT: I've added an extra group to first select max-date-per-id, and then join on this to get max-sequence-per-max-date-per-id before joining to the main table to get all columns.
I have considered your table name as employee..
check the below thing helped you.
select * from employee emp1
join (select Id, max(Date) as dat, max(sequence) as seq from employee group by id) emp2
on emp1.id = emp2.id and emp1.sequence = emp2.seq and emp1.date = emp2.dat
I'm a fan of using the WITH clause in SELECT statements to organize the different steps. I find that it makes the code easier to read.
WITH max_date(max_date)
AS (
SELECT MAX(Date)
FROM my_table
),
max_seq(max_seq)
AS (
SELECT MAX(Sequence)
FROM my_table
WHERE Date = (SELECT md.max_date FROM max_date md)
)
SELECT *
FROM my_table
WHERE Date = (SELECT md.max_date FROM max_date md)
AND Sequence = (SELECT ms.max_seq FROM max_seq ms);
You should be able to optimize this further as needed.