Given a table of random numbers as follows:
** Person table schema **
Name
Marks1
Marks2
I want to return a table with similar structure and headings, where if the sum of a column is odd, the column shows the maximum value for that column, and when the sum is even, it shows the minimum value by using a case statement.
** output table schema **
Marks1
Marks2
I've tried the following code.
select Marks1,Marks2 ,
(case
when mod(sum(Marks1),2)=0 then
min(Marks1)
else max(Marks1)
end) as Marks1 ,
(case
when mod(sum(Marks2),2)=0 then
min(Marks2)
else max(Marks2)
end) as Marks2
from numbers
group by Marks1;
Sample output -
TABLE
Ash 56 45
David 45 35
Output -
56 35
As 56+45 = 101 odd number so output 56(max number). Whereas in marks2 column, 45+35 =80, even number so output 35(min number).
Can anyone tell me what's wrong with it? Thanks in advance.
Use a CTE to get your min(), max(), and sum() values. Then use case to determine what values to display.
Since your problem statement and sample results do not match, I followed your sample results to return max() on an odd sum(). You can switch this by changing the two case statements from 1 to 0.
Working fiddle
with totals as (
select sum(marks1) as marks1sum,
min(marks1) as marks1min,
max(marks1) as marks1max,
sum(marks2) as marks2sum,
min(marks2) as marks2min,
max(marks2) as marks2max
from numbers
)
select case mod(marks1sum, 2)
when 1 then marks1max
else marks1min
end as marks1,
case mod(marks2sum, 2)
when 1 then marks2max
else marks2min
end as marks2
from totals;
You are reusing marks1 and marks2 when aliasing your third and fourth column which is colliding. Try using different name.
Related
I have the following table in Postgresql. The first 4 records are the base data and the others were generated with the ROLLUP function.
I want to add a column "grp_1" that will display the first non-null value of the columns grp1_l1, grp2_l2 and grp2_l3
I can get to the desired result by nesting 3 "case" functions using the SQL below, but my real table has 4 groups with each 8 to 10 columns (so a lot of nested "case" function).
sql:
SELECT grp1_l1, grp1_l2, grp1_l3, case when grp1_l1 is not null then grp1_l1 else case when grp1_l2 is not null then grp1_l2 else case when grp1_l3 is not null then grp1_l3 else null end end end as grp1, value
FROM public.query_test;
Is there a better and more scalable to handle this requirement ? Any suggestions are welcome.
The id will not always have 3 digits, that is just the case in my example here
Use coalesce() it's defined as "returns the first of its arguments that is not null" - which is exactly what you want.
coalesce(grp1_l1, grp1_l2, grp1_l3)
I may be trying it wrong. I am looking for any approach which is best.
Requirement:
My Query joins 4-5 tables based on few fields.
I have a column called product id. In my table there are 1.5 million rows. Out of those only 10% rows has product ids with the following attribute
A300X-%
A500Y-%
300,500, 700 are valid model numbers. X and Y are classifications. My query picks all the systems.
I have a check as follows
CASE
WHEN PID LIKE 'A300X%'
THEN 'A300'
...
END AS MODEL
Similarly
CASE
WHEN PID LIKE 'A300X%'
THEN 'X'
...
END AS GENRE
I am looking for the best option from the below
How do I Combine both case statement and add another[third] case which will have these two cases. i.e
CASE
WHEN desc in ('AAA')
First Case
Second Case
ELSE
don't do anything for other systems
END
Is there any regex way of doing this? Before first - take the string. Look for X, Y and also 300,500,700.
Is there any other way of doing this? Or doing via code is the best way?
Any suggestions?
EDIT:
Sample desc:
AAA,
SoftwARE,
sw-app
My query picks all the desc. But the case should be running for AAA alone.
And Valid models are
A300X-2x-P
A500Y-5x-p
A700X-2x-p
A50CE-2x-P
I have to consider only 300,500,700. And the above two cases.
Expected result:
MODEL GENRE
A300 X
A500 Y
A300 Y
Q: How do I Combine both CASE statement expressions
Each CASE expression will return a single value. If the requirement is to return two separate columns in the resultset, that will require two separate expressions in the SELECT list.
For example:
DESC PID model_number genre
---- ---------- ------------ ------
AAA A300X-2x-P 300 X
AAA A500Y-5x-p 500 Y
AAA A700X-2x-p 700 X
AAA A50CE-2x-P (NULL) (NULL)
FOO A300X-2x-P (NULL) (NULL)
There will need to be an expression to return the model_number column, and a separate expression to return the genre column.
It's not possible for a single expression to return two separate columns.
Q: and add another[third] case which will have these two cases.
A CASE expression returns a value; we can use a CASE expression almost anywhere in a SQL statement where we can use a value, including within another CASE expression.
We can also combine multiple conditions in a WHEN test with AND and OR
As an example of combining conditions and nesting CASE expressions ditions...
CASE
WHEN ( ( t.PID LIKE '_300%' OR t.PID LIKE '_500%' OR t.PID LIKE '_700%' )
AND ( t.DESC = 'AAA' )
)
THEN CASE
WHEN ( t.PID LIKE '____X%' )
THEN 'X'
WHEN ( t.PID LIKE '____Y%' )
THEN 'Y'
ELSE NULL
END
ELSE NULL
END AS `genre`
There are other expressions that will return an equivalent result; the example shown here isn't necessarily the best expression. It just serves as a demonstration of combining conditions and nesting CASE expressions.
Note that to return another column model we would need to include another expression in the SELECT list. Similar conditions will need to be repeated; it's not possible to reference the WHEN conditions in another CASE expression.
Based on your sample data, logic such as this would work:
(CASE WHEN REGEXP_LIKE(PID, '^A[0-9]{3}[A-Z]-')
THEN SUBSTR(PID, 1, 4)
ELSE PID
END) AS MODEL
(CASE WHEN REGEXP_LIKE(PID, '^A[0-9]{3}[A-Z]-')
THEN SUBSTR(PID, 5, 1)
ELSE PID
END) AS GENRE
This assumes that the "model number" always starts with "A" and is followed by three digits (as in your example data). If the model number is more complicated, you may need regexp_substr() to extract the values you want.
I am using sum function inside case statement. I want to do selective summation of rows.
case when
type in ('A','B')
then nvl(SUM(Amount_1),Amount)
else Amount
Two columns are there Amount and Amount_1 and for the Amount_1 column, I want to remove few rows based on some condition C1. For e.g. If I have 10 rows that have type in A and based on condition C1 I am getting only 8 rows then I want to sum Amount_1 column on the basis of 8 rows only.
I think you have the basic logic understood correctly, but your syntax is a bit off. You should be using the CASE expression inside the SUM() function, not the other way around.
SELECT type,
SUM(CASE WHEN type IN ('A', 'B')
THEN COALESCE(Amount_1, Amount) ELSE Amount END) AS type_sum -- ELSE 0 ?
FROM yourTable
This will compute the sum of COALESCE(Amount_1, Amount) for those records where the type is either A or B, otherwise it will use Amount in the sum. If you intended to not count non-matching records at all, then modify my query by using ELSE 0 in the CASE expression.
I have a table that has an integer column from which I am trying to get a few counts from. Basically I need four separate counts from the same column. The first value I need returned is the count of how many records have an integer value stored in this column between two values such as 213 and 9999, including the min and max values. The other three count values I need returned are just the count of records between different values of this column. I've tried doing queries like...
SELECT (SELECT Count(ID) FROM view1 WHERE ((MyIntColumn BETWEEN 213 AND 9999));)
AS Value1, (SELECT Count(ID) FROM FROM view1 WHERE ((MyIntColumn BETWEEN 500 AND 600));) AS Value2 FROM view1;
So there are for example, ten records with this column value between 213 and 9999. The result returned from this query gives me 10, but it gives me the same value of 10, 618 times which is the number of total records in the table. How would it be possible for me to only have it return one record of 10 instead?
Use the Iif() function instead of CASE WHEN
select Condition1: iif( ), condition2: iif( ), etc
P.S. : What I used to do when working with Access was have the iif() resolve to 1 or 0 and then do a SUM() to get the counts. Roundabout but it worked better with aggregation since it avoided nulls.
SELECT
COUNT(CASE
WHEN MyIntColumn >= 213 AND MyIntColumn <= 9999
THEN MyIntColumn
ELSE NULL
END) AS FirstValue
, ??? AS SecondValue
, ??? AS ThirdValue
, ??? AS FourthValue
FROM Table
This doesn't need nesting or CTE or anything. Just define via CASE your condition within COUNTs argument.
I dont really understand what You want in the second, third an fourth column. Sounds to me, its very similar to the first one.
Reformatted, your query looks like:
SELECT (
SELECT Count(ID)
FROM view1
WHERE MyIntColumn BETWEEN 213 AND 9999
) AS Value1
FROM view1;
So you are selecting a subquery expression that is not related to the outer query. For each row in view1, you calculate the number of rows in view1.
Instead, try to do the calculation once. You just have to remove your outer query:
SELECT Count(ID)
FROM view1
WHERE MyIntColumn BETWEEN 213 AND 9999;
OLEDB Connection in MS Access does not support key words CASE and WHEN .
You can only use iif() function to count two, three.. values in same columns
SELECT Attendance.StudentName, Count(IIf([Attendance]![Yes_No]='Yes',1,Null)) AS Yes, Count(IIf([Attendance]![Yes_No]='No',1,Null)) AS [No], Count(IIf([Attendance]![Yes_No]='Not',1,Null)) AS [Not], Count(IIf([Attendance]![Yes_No],1,Null)) AS Total
FROM Attendance
GROUP BY Attendance.StudentName;
I've got a table called datapoints with about 150 columns and 2600 rows. I know, 150 columns is too much, but I got this db after importing a csv and it is not possible to shrink the number of columns.
I have to get some statistical stuff out of the data. E.g. one question would be:
Give me the total number of fields (of all columns), which are null. Does somebody have any idea how I can do this efficiently?
For one column it isn't a problem:
SELECT count(*) FROM datapoints tb1 where 'tb1'.'column1' is null;
But how can I solve this for all columns together, without doing it by hand for every column?
Best,
Michael
Building on Lamak's idea, how about this idea:
SELECT (N * COUNT(*)) - (
COUNT(COLUMN_1)
+ COUNT(COLUMN_2)
+ ...
+ COUNT(COLUMN_N)
)
FROM DATAPOINTS;
where N is the number of columns. The trick will be in making the summation series of COUNT(column), but that shouldn't be too terrible with a good text editor and/or spreadsheet.
i don't think there is an easy way to do it. i'd get started on the 150 queries. you only have to replace one word (column name) each time.
Well, COUNT (and most aggregations funcions) ignore NULL values. In your case, since you are using COUNT(*), it counts every row in the table, but you can do that on any column. Something like this:
SELECT TotalRows-Column1NotNullCount, etc
FROM (
SELECT COUNT(1) TotalRows,
COUNT(column1) Column1NotNullCount,
COUNT(column2) Column2NotNullCount,
COUNT(column3) Column3NotNullCount ....
FROM datapoints) A
To get started it's often helpful to use a visual query tool to generate a field list and then use cut/paste/search/replace or manipulation in a spreadsheet program to transform it into what is needed. To do it all in one step you can use something like:
SELECT SUM(CASE COLUMN1 WHEN NULL THEN 1 ELSE 0 END) +
SUM(CASE COLUMN2 WHEN NULL THEN 1 ELSE 0 END) +
SUM(CASE COLUMN3 WHEN NULL THEN 1 ELSE 0 END) +
...
FROM DATAPOINTS;
With a visual query builder you can quickly generate:
SELECT COLUMN1, COLUMN2, COLUMN3 ... FROM DATAPOINTS;
You can then replace the comma with all the text that needs to appear between two field names followed by fixing up the first and last fields. So in the example search for "," and replace with " WHEN NULL 1 ELSE 0 END) + SUM(CASE " and then fix up the first and last fields.