I have to Case statements that count the same column just with a differnt criteria. The problem i am having is that the first case creates a null entry in the Test2 column but then counts it on my second case statement and leaves the Test 1 column null. I would like to have both counts side by side instead of created a duplicate row.
select m.no,
Case when itemtype = 'S' THEN count(ITEMKEY) end as Test1,
case when ItemType='C' THEN count(ITEMKEY) END as Test2
from test m
I'm pretty sure you want conditional aggregation. The case expression is an argument to the aggregation function:
select m.no,
sum(case when itemtype = 'S' then 1 else 0 end) as test1,
sum(case when itemtype = 'C' then 1 else 0 end) as test2
from test m
group by m.no;
This assumes that itemKey is never null, so the count() is just counting rows.
Following query can display records which having Itemtype 'S' or 'C' with count of itemkey. if itemkey is null it will display 0 else count of item key
select m.no,
Case when isnull( m.itemtype = 'S',0) THEN (select count(a.ITEMKEY) from test a where a.itemtype = 'S' ) else 0 end as Test1,
case when isnull( m.itemtype='C',0) THEN (select count(b.ITEMKEY) from test b where b.itemtype = 'C') else 0 END as Test2
from test m
Related
I have a table which consists of data where in I'm having trouble counting the corresponding rows.
Here is the sample table:
I am expecting an output like this:
You can do conditional aggregation:
select
sum(case when result = 'X' then 1 else 0 end) count_x,
sum(case when result is null then 1 else 0 end) count_blank
from mytable
I assume that by blank you mean null. If not, then you can change the condition in the second sum() from result is null to result = ''.
If you are running MySQL, this can be shortened a little:
select
sum(result = 'X') count_x,
sum(result is null) count_blank
from mytable
Lets say I have the following table:
FKEY A B C D E F
'A' 1 0 1 0 1 0
'A' 0 1 1 1 0 0
Now i want to make a group by FKEY but I just want to know if the A-F columns has 1 in one, all or none of the grouped rows.. The resulton the above table would be:
FKEY A B C D E F
'A' S S A S S N
..where S is "some", A is "all" and N is "none".
What would be the best approach to make this query. I could so some nested queries, but isnt there a smarter way?
In my real life data, the 1's and 0's are actually DATETIME and NULL's
You can use case and aggregation:
select fkey,
(case when sum(a) = 0 then 'N'
when sum(a) = count(*) then 'A'
else 'S'
end) as a,
(case when sum(b) = 0 then 'N'
when sum(b) = count(*) then 'A'
else 'S'
end) as b,
. . .
from t
group by fkey;
The above assumes that the values are only 0 and 1. If that is the case, you can actually phrase this as:
(case when max(a) = 0 then 'N'
when min(a) = 1 then 'A'
else 'S'
end) as a,
You mentioned that your 0 and 1 are actually null or non null dates. Here's a modified version of Gordon's query that caters for that:
select fkey,
(case when count(datecol) = 0 then 'all dates are null'
when count(datecol) = count(*) then 'all dates are filled'
else 'some are null, some filled'
end) as a,
...
from t
group by fkey;
COUNT(null) is 0, COUNT('2001-01-01') is 1, COUNT(*) is the row count independent of any variable. Hence, if our count of the dates was 0, all must be null. If the count of the dates was equal to the count of the rows, then all must be filled with some value, otherwise it's a mix
I am trying to get a count on values that might appear in 3 different columns but only require the count of unique values. Microsoft SQL.
Eg. value X might appear in column A, B, or C or all 3 but need to make sure I only get a unique count of value X no matter what columns it comes under.
Thanks!
If you want to count each individual occurrence of X in any column A, B, or C, then the following should work:
SELECT
SUM(CASE WHEN A = 'X' THEN 1 ELSE 0 END) +
SUM(CASE WHEN B = 'X' THEN 1 ELSE 0 END) +
SUM(CASE WHEN C = 'X' THEN 1 ELSE 0 END)
FROM yourTable
Is this what you are looking for? This will Count only 1 occurrence per row regardless of how many columns it is found in.
SELECT
ID
,SUM(CASE WHEN ColA = 'X' OR ColB = 'X' OR ColC = 'X' THEN 1 ELSE 0 END) AS ValueCount
FROM
TABLENAME
GROUP BY
ID
I guess I should show it without the group by too because you don't specify a grouping.
SELECT
,SUM(CASE WHEN ColA = 'X' OR ColB = 'X' OR ColC = 'X' THEN 1 ELSE 0 END) AS ValueCount
FROM
TABLENAME
I've a table in my database for which I need to check if all rows have one field not null.
If there are no row or if there is at least 1 row with the field null => true
If there are rows and they are all with the field not null => False
Is there a way to do this in on simple query? Or I need to check if my table is empty first then if it's not check if I've a row with the field value empty ?
This will count how many NULL values you have in a field;
SELECT
SUM(CASE WHEN FieldName IS NULL THEN 1 ELSE 0 END) NullValues
FROM TableName
Will return 0 if there are no NULL values, and will return the number of NULLS if there are any present.
If you actually want to return a value as 'True' or 'False' then do this;
SELECT CASE
WHEN a.NullValues > 0
THEN 'True'
ELSE 'False'
END CheckField
FROM (
SELECT
SUM(CASE WHEN FieldName IS NULL
THEN 1
ELSE 0
END) NullValues
FROM TableName
) a
Use count(*) and count(field) and compare the two:
select
case when count(*) > 0 and count(*) = count(field) then 1 -- not empty and no nulls
else 0 end as isgood
from mytable;
Oracle SQL has no boolean data type , so I use 1 for true and 0 for false. You can replace this with whatever you like (e.g. 'true' instead of 1 and 'false' instead of 0).
As to turning this into a predicate (correlated to a main query), you'd use something along the lines of:
select ...
from main
where exists
(
select 1
from mytable
where mytable.colx = main.coly
having count(*) > 0 and count(*) = count(field)
);
You can do this with aggregation. However, it is difficult to understand what you are asking for. If you want to check that a field has no NULL values, you can do:
select (case when count(*) > 0 then 1 else 0 end) as HasNullValues
from t
where field is null;
Alternate way I found using max with putting null first:
select case when
max(field) keep (dense_rank first order by datfin desc nulls first) is null then 1
else 0 end as flag
from MYTABLE;
I'm after a CTE which I want to return two columns, one with the total number of 1's and one with the total number of 0's. Currently I can get it to return one column with the total number of 1's using:
WITH getOnesAndZerosCTE
AS (
SELECT COUNT([message]) AS TotalNo1s
FROM dbo.post
WHERE dbo.checkletters([message]) = 1
--SELECT COUNT([message]) AS TotalNo0s
--FROM dbo.post
--WHERE dbo.checkletters([message]) = 0
)
SELECT * FROM getOnesAndZerosCTE;
How do I have a second column called TotalNo0s in the same CTE which I have commented in there to show what I mean.
Using conditional aggregation:
WITH getOnesAndZerosCTE AS(
SELECT
TotalNo1s = SUM(CASE WHEN dbo.checkletters([message]) = 1 THEN 1 ELSE 0 END),
TotalNo0s = SUM(CASE WHEN dbo.checkletters([message]) = 0 THEN 1 ELSE 0 END)
FROM post
)
SELECT * FROM getOnesAndZerosCTE;
For using COUNT() directly just be aware that it counts any NON-NULL values. You can omit the ELSE condition which implicitly returns NULL if not stated
SELECT
COUNT(CASE WHEN dbo.checkletters([message]) = 1 THEN 1 END) TotalNo1s
, COUNT(CASE WHEN dbo.checkletters([message]) = 0 THEN 1 END) TotalNo0s
FROM post
or, explicitly state NULL
SELECT
COUNT(CASE WHEN dbo.checkletters([message]) = 1 THEN 1 ELSE NULL END) TotalNo1s
, COUNT(CASE WHEN dbo.checkletters([message]) = 0 THEN 1 ELSE NULL END) TotalNo0s
FROM post
You can do it without CTE
select count(message) total,
dbo.checkletters(message) strLength
from post
group by dbo.checkletters(message)
having dbo.checkletters(message) in (1, 2) //All the messages with length 1 or 2