I have an SQL query like :
SELECT SUM(CASE WHEN <table_name>.status = '2' THEN 1 ELSE 0 END) FROM <table name>.
I want to write the corresponding Ecto Query for the above. Something like:
from t in <table_name>, select: sum(...)
What is the analogy to "case-when" in the above case?
Like the comment said, you can use fragment/1:
query = from t in <Model>, select: fragment("SUM(CASE WHEN status = ? THEN 1 ELSE 0 END)", 2)
If you want to specify the table, this works for me:
query = from t in <Model>, select: fragment("SUM(CASE WHEN ? = ? THEN 1 ELSE 0 END)", t.status, 2)
You can also leverage on macros to extend Ecto query language:
defmacro case_when(condition, do: then_expr, else: else_expr) do
quote do
fragment(
"CASE WHEN ? THEN ? ELSE ? END",
unquote(condition),
unquote(then_expr),
unquote(else_expr)
)
end
end
Then use it like this:
query = from t in <Model>,
select: case_when t.status == 2
do 1
else 0
end
Related
My SQL code looks like this:
SELECT
Scores.PupilId, Scores.BoysName, Scores.FormGroup,
IF (Scores.FormGroup = "10SB", "Great", "ok")
FROM
Scores
I get this message
no such function: if: SELECT Scores.PupilId, Scores.BoysName, Scores.FormGroup,
if(Scores.FormGroup="10SB","Great","ok")
FROM Scores
This is flat file database
Can anyone please help me understand why I am getting a message?
The correct ANSI-standard conditional expression in SQL is the case expression:
SELECT Scores.PupilId, Scores.BoysName, Scores.FormGroup,
(CASE WHEN Scores.FormGroup = '10SB' THEN 'Great' ELSE 'ok' END)
FROM Scores ;
I have an issue that I'm hoping you can help me with. I am trying to create charting data for performance of an application that I am working on. The first step for me to perform two select statements with my feature turned off and on.
SELECT onSet.testName,
avg(onSet.elapsed) as avgOn,
0 as avgOff
FROM Results onSet
WHERE onSet.pll = 'On'
GROUP BY onSet.testName
union
SELECT offSet1.testName,
0 as avgOn,
avg(offSet1.elapsed) as avgOff
FROM Results offSet1
WHERE offSet1.pll = 'Off'
GROUP BY offSet1.testName
This gives me data that looks like this:
Add,0,11.4160277777777778
Add,11.413625,0
Delete,0,4.5245277777777778
Delete,4.0039861111111111,0
Evidently union is not the correct feature. Since the data needs to look like:
Add,11.413625,11.4160277777777778
Delete,4.0039861111111111,4.5245277777777778
I've been trying to get inner joins to work but I can't get the syntax to work.
Removing the union and trying to put this statement after the select statements also doesn't work. I evidently have the wrong syntax.
inner join xxx ON onSet.testName=offset1.testName
After getting the data to be like this I want to apply one last select statement that will subtract one column from another and give me the difference. So for me it's just one step at a time.
Thanks in advance.
-KAP
I think you can use a single query with conditional aggregation:
SELECT
testName,
AVG(CASE WHEN pll = 'On' THEN elapsed ELSE 0 END) AS avgOn,
AVG(CASE WHEN pll = 'Off' THEN elapsed ELSE 0 END) AS avgOff
FROM Results
GROUP BY testName
I just saw the filemaker tag and have no idea if this work there, but on MySQL I would try something along
SELECT testName, sum(if(pll = 'On',elapsed,0)) as sumOn,
sum(if(pll = 'On',1,0)) as numOn,
sum(if(pll ='Off',elapsed,0)) as sumOff,
sum(if(pll ='Off',1,0)) as numOff,
sumOn/numOn as avgOn,
sumOff/numOff as avgOff
FROM Results
WHERE pll = 'On' or pll='Off'
GROUP BY testName ;
If it works for you then this should be rather efficient as you do not need to join. If not, thumbs pressed that this triggers another idea.
The difficulty you have with the join you envisioned is that the filtering in the WHERE clause is performed after the join was completed. So, you would still not know what records to use to compute the averages. If the above is not implementable with FileMaker then check if nested queries work. You would then
SELECT testName, on.avg as avgOn, off.avg as avgOff
FROM ( SELECT ... FROM Results ...) as on, () as off
JOIN on.testName=off.testName
If that is also not possible then I would look for temporary tables.
OK guys... thanks for the help again. Here is the final answer. The statement below is FileMaker custom function that takes 4 arguments (platform, runID, model and user count. You can see the sql statement is specified. FileMaker executeSQL() function does not support nested select statements, does not support IF statements embedded in select statements (calc functions do of course) and finally does not support the SQL keyword VALUES. FileMaker does support the SQL keyword CASE which is a little more powerful but is a bit wordy. The select statement is in a variable named sql and result is placed in a variable named result. The ExecuteSQL() function works like a printf statement for param text so you can see the swaps do occur.
Let(
[
sql =
"SELECT testName, (sum( CASE WHEN PLL='On' THEN elapsed ELSE 0 END)) as sumOn,
sum( CASE WHEN PLL='On' THEN 1 ELSE 0 END) as countOn,
sum( CASE WHEN PLL='Off' THEN elapsed ELSE 0 END) as sumOff,
sum( CASE WHEN PLL='Off' THEN 1 ELSE 0 END) as countOff
FROM Results
WHERE Platform = ?
and RunID = ?
and Model = ?
and UserCnt = ?
GROUP BY testName";
result = ExecuteSQL ( sql ; "" ; ""
; platform
; runID
; model
; userCnt )
];
getAverages ( Result ; "" ; 2 )
)
For those interested the custom function looks like this:
getAverages( result, newList, pos )
Let (
[
curValues = Substitute( GetValue( data; pos ); ","; ¶ );
sumOn = GetValue( curValues; 2 ) ;
countOn = GetValue( curValues; 3 );
sumOff = GetValue( curValues; 4 );
countOff = GetValue( curValues; 5 );
avgOn = sumOn / countOn;
avgOff = sumOff / countOff
newItem = ((avgOff - avgOn) / avgOff ) * 100
];
newList & If ( pos > ValueCount( data); newList;
getAverages( data; If ( not IsEmpty( newList); ¶ ) & newItem; pos + 1 ))
)
I need to write an expression for derived column. My column name is 'status'. what is the equivalent expression in SSIS for the below condition?
Case when Status Like '%Open%' then 0
when Status like '%Won%' then 1
when status like "%Lost%' then 2 Else 3
Thanks in advance
Give this a shot:
FINDSTRING(Status,"Open",1) > 0 ? 0 : (FINDSTRING(Status,"Won",1) > 0 ? 1 : (FINDSTRING(Status,"Lost",1) > 0 ? 2 : 3))
I want to use parameter in my query but I can't handle with it
I have 3 big selects to raport and I just want to use parameter for some part of code which depends from choice
I have 3 different Where conditions
1st
..WHERE A.CANCELLED = 'FALSE' AND a.open_amount!=0 AND A.IDENTITY = '&client_id'..
2nd
...WHERE A.CANCELLED = 'FALSE' AND A.IDENTITY = '&client_id' ...
3rd
WHERE AND A.CANCELLED = 'FALSE' AND a.invoice_amount != a.open_amount AND A.IDENTITY = '&client_id'
I tried with decode but I guess it could be ok if there would be value in 2nd case but there isn't and I cant decode like this
WHERE decode(xxx,x1,'AND a.open_amount!= 0',x2,'',x3, 'AND a.invoice_amount != a.open_amount')
How I should solve that problem any tips?
Do you mean, if the first "where condition" OR the second OR the third is/are TRUE, you want the overall to be TRUE (select the row), and you are looking for a simplified way to write it? That is, without simply combining them with OR?
To achieve that, you don't need CASE and nested CASE statements or DECODE. You could do it like this:
WHERE A.CANCELLED = 'FALSE'
AND A.IDENTITY = '&client_id'
AND ( (xxx = x1 AND a.open_amount != 0) OR (xxx = x2) OR
(xxx = x3 AND a.invoice_amount != a.open_amount) )
This is more readable, the intent is clear, it will be easier to modify if needed, ...
You can try something like -
WHERE A.CANCELLED = 'FALSE'
AND A.IDENTITY = '&client_id'
AND a.open_amount <>
(CASE
WHEN x1 THEN 0
WHEN x2 THEN a.open_amount + 1 -- This needs to be something that is always TRUE, to nullify the condition
WHEN x3 THEN a.invoice_amount
END);
Edit: This is based on the assumption that a.open_amount is a NUMBER and uses a quick hack where we create an always TRUE condition like x <> x + 1. You should probably change this to whatever suits you better based on your data.
Is there any way to do the following in HQL:
SELECT
case when flag = true then SUM(col1) else SUM(col2)
FROM
myTable
I guess you can (3.6, 4.3) [inline edit] ...for where-clauses:
"Simple" case, case ... when ... then ... else ... end, and "searched" case, case when ... then ... else ... end
Apparently the ability to do this was added in 3.0.4, with the limitation that you cannot use sub-selects in the else clause.
See Hibernate-Forum: https://forum.hibernate.org/viewtopic.php?t=942197
Answer from Team (Gavin):
case is supported in the where clause, but not in the select clause in HB3.
And seen in JIRA with State "Unresolved".
Below you can find a working query (hibernate on postgresql) that uses 2 case statements to replace a boolean value with the corresponding textual representation.
SELECT
CASE ps.open WHEN true THEN 'OPEN'
else 'CLOSED' END,
CASE ps.full WHEN true THEN 'FULL'
else 'FREE' END,
ps.availableCapacity
FROM ParkingState as ps
I facing the same problem in HQL then I solved the following query is
select CONCAT(event.address1,', ', CASE WHEN event.address2 IS NULL THEN '' ELSE concat(event.address2,', ') END, event.city from EventDetail event where event.startDate>=:startDate and event.endDate<=:endDate;
We use hibernate HQL query extensively and I think finally there is a hackish way of doing such a thing :
Assuming we originally had a query of
i2.element.id = :someId
Then decided to expand this to be something like this:
((i.element.id = :someId and i2.element.id=:someId) or (i2.element.id = :someId))
But there was an issue where we want it to only lookup for this based on classType so a case statement:
(case when type(i)=Item then
((i.element.id = :someId and i2.element.id=:someId) or (i2.element.id = :someId))
else
i.element.id = :someId
end)
Above will not work you could make an easy version of above work by doing:
(case when type(i)=Item then
i2.element.id
else
i.element.id
end)=:elementId
But this does not actually do what we need it to do, we want it to do exact above query, so knowing you can assign a variable at the end of a case statement in there where bit of HQL:
(
(
(case when
type(r)=Item then
i.element.id
else
i.element.id end) = :elementId
and
(case when
type(r)=Item then
i2.element.id
else
i.element.id end) = :elementId
)
or
(case when
type(r)=Item then
i2.element.id
else
i.element.id end) = :elementId
)
I have managed to make the query now work based on case statement, sure it is a lot more long winded but actually does the same as the first instance
This is an example using a string comparison in the condition:
SELECT CASE f.type WHEN 'REMOVE'
THEN f.previousLocation
ELSE f.currentLocation
END
FROM FileOperation f