I want max startdate but there is a NULL data, it will be null.
Sample data is as follows:
DECLARE #Tbl TABLE (Id INT, StartDate DATETIME)
INSERT INTO #Tbl
VALUES (1, NULL),
(1, '2016.07.30'),
(1, '2016.07.05'),
(1, '2016.07.05'),
(2, '2016.07.07'),
(2, '2016.07.05'),
(3, '2016.07.05'),
(3, NULL)
My Query:
SELECT Id, MAX(StartDate) AS StartDate
FROM #Tbl
GROUP BY Id
Output:
Id StartDate
----------- ----------
1 2016-07-30
2 2016-07-07
3 2016-07-05
Desired Output:
Id StartDate
----------- ----------
1 NULL
2 2016-07-07
3 NULL
To solve this problem we can use a count function that behave different in two cases:
when we use count(*) then all rows are count (also with null value)
when we use count(someFieldName) then only rows with not null value are count
You can see this different behaviour on this example using sample data from the question
select Id, count(*) as count_all, count(StartDate) as count_StartDate
from #Tbl
group by Id;
On the output we can see this
Id count_all count_StartDate
1 4 3
2 2 2
3 2 1
We can use this different behaviour to solve problem from question by this query
select Id, case when count(*) = count(StartDate)
then max(StartDate)
else null
end as StartDate
from #Tbl
group by Id
On the output we can see the desired result
Id StartDate
1 NULL
2 2016-07-07 00:00:00.000
3 NULL
Found the result.
SELECT Id, CASE
WHEN MAX(COALESCE(StartDate, '2099.01.01')) = '2099.01.01' THEN NULL
ELSE MAX(StartDate) END AS StartDate
FROM #Tbl
GROUP BY Id
Related
I will give you example of table that I have:
Supplier | Value
sup1 | 4
sup2 | 1
sup1 | 0
sup1 | 3
sup2 | 5
I need a result that will do average by supplier, but if there is value 0 for a supplier, do not average, but return 0 instead
It should look like this:
Supplier | Value
sup1 | 0
sup2 | 3
This is a little trick but it should work :
SELECT Supplier,
CASE WHEN MIN(ABS(Value)) = 0 THEN 0 ELSE AVG(Value) END
FROM TableTest
GROUP BY Supplier
EDIT : Using the ABS() function let you avoid having problems with negative values
DECLARE #TAB TABLE (SUPPLIER VARCHAR(50),VALUE INTEGER)
INSERT INTO #TAB
SELECT 'sup1',4
UNION ALL
SELECT 'sup2',1
UNION ALL
SELECT 'sup1',0
UNION ALL
SELECT 'sup1',3
UNION ALL
SELECT 'sup2',5
SELECT * FROM #TAB
SELECT T1.SUPPLIER,CASE WHEN EXISTS(SELECT 1 FROM #TAB T WHERE T.SUPPLIER = T1.SUPPLIER AND T.VALUE = 0) THEN 0 ELSE AVG(T1.VALUE) END AS VALUE
FROM #TAB T1
GROUP BY T1.SUPPLIER
Result
SUPPLIER VALUE
sup1 0
sup2 3
Using the following query is one of the way to do.
First I push the supplier which has the Value = 0, then based on the result, I will do the remaining calculation and finally using UNION to get the expected result:
DECLARE #ZeroValue TABLE (Supplier VARCHAR (20));
INSERT INTO #ZeroValue (Supplier)
SELECT Supplier FROM TestTable WHERE Value = 0
SELECT Supplier, 0 AS Value FROM #ZeroValue
UNION
SELECT T.Supplier, AVG(T.Value) AS Value
FROM TestTable T
JOIN #ZeroValue Z ON Z.Supplier != T.Supplier
GROUP BY T.Supplier
Schema used for the sample:
CREATE TABLE TestTable (Supplier VARCHAR (20), Value INT);
INSERT INTO TestTable (Supplier, Value) VALUES
('sup1', 4), ('sup2', 1), ('sup1', 0), ('sup1', 3), ('sup2', 5);
Please find the working demo on db<>fiddle
How to achieve 1 column 2 rows to 2 columns 1 row on DB2 please?
eg :
select value from <tablename> WHERE name='VAR' ORDER BY effectivedate DESC FETCH FIRST 2 ROWS ONLY;
which gives
VAR
----
12
57
But I want to get
VAR1,VAR2
-----------
12 ,57
Thanks very much!
Typically, the best way to "pivot" rows to columns is to aggregate over CASE statements.
For example
SELECT MAX(CASE WHEN RN = 1 THEN value END) AS VAR1
, MAX(CASE WHEN RN = 2 THEN value END) AS VAR2
, MAX(CASE WHEN RN = 3 THEN value END) AS VAR3
, MAX(CASE WHEN RN = 4 THEN value END) AS VAR4
FROM (
SELECT *, ROW_NUMBER() OVER(ORDER BY effectivedate DESC) AS RN
FROM a_table T
)
will return this
VAR1 VAR2 VAR3 VAR4
---- ---- ---- ----
12 57 1 NULL
using the table and data in my other answer
which would return
Use substring and aliases
SELECT
SUBSTR(VAR, 1,LOCATE(' ',VAR)-1) as VAR1
, SUBSTR(VAR, LOCATE(' ',VAR)+1) as VAR2
FROM YOURTABLE;
Basically breaking on space, if you have fixed length you can use without locate.
There are many ways to do this. If you are on Db2 LUW 11.1 or above, this will work
SELECT * FROM TABLE(VALUES
( ( select value from a_table WHERE name='VAR' ORDER BY effectivedate DESC FETCH FIRST 1 ROW ONLY)
, ( select value from a_table WHERE name='VAR' ORDER BY effectivedate DESC OFFSET 1 ROW FETCH NEXT 1 ROW ONLY )
)) AS t(VAR1, VAR2)
and with this table and data
create TABLE a_table( value int, name char(3), effectivedate date);
INSERT INTO a_table values (12,'VAR','2018-01-10'),(57,'VAR', '2018-01-09'),(1,'VAR','2018-01-08');
will return this result
VAR1 VAR2
---- ----
12 57
I have following table:
========================
Id SubCode Title
========================
1 1 test1
1 2 test2
1 3 NULL
1 4 NULL
2 1 k1
2 2 k2
2 3 k3
2 4 NULL
No I want to select latest rows which their title is not null, for example for Id 1 then query must show test2 and for Id 2 it must be k3:
========================
Id SubCode Title
========================
1 2 test2
2 3 k3
I have written this query:
select t.Id, t.SubCode, t.Title from Test t
inner join (
select max(Id) as Id, max(SubCode) as SubCode
from Test
group by Id
) tm on t.Id = tm.Id and t.SubCode = tm.SubCode
But this code gives the wrong result:
========================
Id SubCode Title
========================
1 4 NULL
2 4 NULL
Any idea?
You forgot to exclude NULLs by writing an appropriate WHERE clause (where title is not null).
However such problems (to get a best / last / ... record) are usually best solved with analytic functions (RANK, DENSE_RANK, ROW_NUMBER) anyway, because with them you access the table only once:
select id, subcode, title
from
(
select id, subcode, title, rank() over (partition by id order by subcode desc) as rn
from test
where title is not null
) ranked
where rn = 1;
You need a Title is not null where clause in your inner select:
select t.Id, t.SubCode, t.Title from Test t
inner join (
select max(Id) as Id, max(SubCode) as SubCode
from Test
where Title is not null
group by Id
) tm on t.Id = tm.Id and t.SubCode = tm.SubCode
I have a table TaggedData with the following fields and data
ID GroupID Tag MyData
** ******* *** ******
1 Texas AA01 Peanut Butter
2 Texas AA15 Cereal
3 Ohio AA05 Potato Chips
4 Texas AA08 Bread
I have a second table of BlockedTags as follows:
ID StartTag EndTag
** ******** ******
1 AA00 AA04
2 AA15 AA15
How do I select from this to return all data matching a given GroupId but NOT in any blocked range (inclusive)? For the data given if the GroupId is Texas, I don't want to return Cereal because it matches the second range. It should only return Bread.
I did try left joins based queries but I'm not even that close.
Thanks
create table TaggedData (
ID int,
GroupID varchar(16),
Tag char(4),
MyData varchar(50))
create table BlockedTags (
ID int,
StartTag char(4),
EndTag char(4)
)
insert into TaggedData(ID, GroupID, Tag, MyData)
values (1, 'Texas', 'AA01', 'Peanut Butter')
insert into TaggedData(ID, GroupID, Tag, MyData)
values (2, 'Texas' , 'AA15', 'Cereal')
insert into TaggedData(ID, GroupID, Tag, MyData)
values (3, 'Ohio ', 'AA05', 'Potato Chips')
insert into TaggedData(ID, GroupID, Tag, MyData)
values (4, 'Texas', 'AA08', 'Bread')
insert into BlockedTags(ID, StartTag, EndTag)
values (1, 'AA00', 'AA04')
insert into BlockedTags(ID, StartTag, EndTag)
values (2, 'AA15', 'AA15')
select t.* from TaggedData t
left join BlockedTags b on t.Tag between b.StartTag and b.EndTag
where b.ID is null
Returns:
ID GroupID Tag MyData
----------- ---------------- ---- --------------------------------------------------
3 Ohio AA05 Potato Chips
4 Texas AA08 Bread
(2 row(s) affected)
So, to match on given GroupID you change the query like that:
select t.* from TaggedData t
left join BlockedTags b on t.Tag between b.StartTag and b.EndTag
where b.ID is null and t.GroupID=#GivenGroupID
I Prefer the NOT EXISTS simply because it gives you more readability, usability and better performance usually in large data (several cases get better execution plans):
would be like this:
SELECT * from TaggedData
WHERE GroupID=#GivenGroupID
AND NOT EXISTS(SELECT 1 FROM BlockedTags WHERE Tag BETWEEN StartTag ANDEndTag)
OrderId OrderCode Description
-------------------------------
1 Z123 Stuff
2 ABC999 Things
3 Z123 Stuff
I have duplicates in a table like the above. I'm trying to get a report of which Orders are duplicates, and what Order they are duplicates of, so I can figure out how they got into the database.
So ideally I'd like to get an output something like;
OrderId IsDuplicatedBy
-------------------------
1 3
3 1
I can't work out how to code this in SQL.
You can use the same table twice in one query and join on the fields you need to check against. T1.OrderID <> T2.OrderID is needed to not find a duplicate for the same row.
declare #T table (OrderID int, OrderCode varchar(10), Description varchar(50))
insert into #T values
(1, 'Z123', 'Stuff'),
(2, 'ABC999', 'Things'),
(3, 'Z123', 'Stuff')
select
T1.OrderID,
T2.OrderID as IsDuplicatedBy
from #T as T1
inner join #T as T2
on T1.OrderCode = T2.OrderCode and
T1.Description = T2.Description and
T1.OrderID <> T2.OrderID
Result:
OrderID IsDuplicatedBy
1 3
3 1