I need help with writing a select clause query.
For example, lets say I have a query like that:
select value from some_table order by value asc;
as a result I get this:
1
2
3
4
5
6
7
8
9
10
but a special query I want to write, is the one which still will give me sorted values, but will put 5 after 8.
this means I need one value to be out of regular order.
it can be described in other way. lets say I have two groups of numbers (example):
A={ a | 1<=a<=118, a!=78 } B={ b | b>118 }
I have a group C=A U B U {78}
and I need all these values sorted like "A,78,B"
Assuming value is integer, you could do this:
SELECT *
FROM tbl
ORDER BY
CASE
WHEN value = 5 THEN 8.5
ELSE value
END
Or to expand upon DCP's answer...
SELECT *
FROM tbl
ORDER BY
CASE
WHEN (Condition for first grouping) THEN 1
WHEN (Condition for second grouping) THEN 2
WHEN (Condition for third grouping) THEN 3
ELSE 4
END
You can use multiple conditions in your order by:
ORDER BY (value BETWEEN 1 AND 118) AND value != 78 DESC,
value > 118 DESC,
value
This will ensure that values which match the first predicate come first, then values matching the second predicate, and finally values matching none of the predicates. If there is a tie (two numbers matching the same predicate) then these numbers are sorted in ascending order.
Note that I haven't tested this in Oracle. It might be necessary to wrap the predicate in a CASE expression (CASE WHEN predicate THEN 1 ELSE 0 END) to get the sorting to work in Oracle.
ORDER BY
(CASE WHEN ((value BETWEEN 1 AND 118) AND value <> 78) THEN 1 ELSE 0 END) DESC,
(CASE WHEN (value > 118) THEN 1 ELSE 0 END) DESC,
value
Order by some CASE-expression to remap your values.
Related
So I essentially want to work around the fact that CASE WHEN stops executing when it finds its first TRUE return.
I'd like to sum every instance of a non-null value between multiple columns, and group these based on my ID. Example table:
id
input1
input2
input3
1
a
null
k
2
null
null
b
3
null
null
null
4
q
null
r
5
x
p
j
6
null
y
q
I would like the output of my function to be:
id
total_inputs
1
2
2
1
3
0
4
2
5
3
6
2
Any work arounds? Is a custom function in order to create a count of unique or non-null entries across multiple columns, grouped by row?
I know I can create a CTE and assign 1's to each non-null column but that seems tedious (my data set has 39 inputs) - and I'd like to have a reusable function I could use again in the future.
You could use a simple aggregation as the following:
Select id,
Count(input1) + Count(input2) + Count(input3) As total_inputs
From table_name
Group By id
Order By id
Noting that Count(inputX) = 0, where inputX is null.
See a demo.
We can simply use:
select ID,
case when input1 is not null then 1 else 0 end
+ case when input2 is not null then 1 else 0 end
+ ...
+ case when input39 is not null then 1 else 0 end as total_inputs
from ...
No need to group by if you want every row (or count, we are not aggregating rows - that is what COUNT()..GROUP BY is for), or CTE.
Also, for some PostgreSQL versions, there is a num_nulls function to count null parameters:
select
, 32-num_nulls(input1, input2, input3, ..., input32)
I have a list of words I need to find in a specific column , "description of what happenned "
this holds anything up to 500 or more characters. I have the script below that does work
However how do I replace the Name column 1.2.3 with the actual name of the word I am looking for with the total next to it.
Just cant get it to display prob something simple.
select GROUPING_ID ( Amoxicillin ,Atorvastatin ) as Name ,count(*) as Total
from ( select case when [description_of_what_happened] like '%Amoxicillin%'
then 1 else 0 end as Amoxicillin ,
case when [description_of_what_happened] like '%Atorvastatin%'
then 1 else 0 end as Atorvastatin
FROM "NAME OF TABLE"
group by grouping sets (() ,(Amoxicillin),(Atorvastatin))
having coalesce (Amoxicillin,1) != 0 and coalesce (Atorvastatin,1) != 0
order by grouping_id (Amoxicillin,Atorvastatin)
row 3 being the total I need row 1 and row 2 to show the name of the product
result as below
Name Total
1 7
2 9
3 4112
You can use strings instead of flags:
select coalesce(Amoxicillin, Atorvastatin, 'Total') as Name,
count(*) as Total
from (select (case when [description_of_what_happened] like '%Amoxicillin%'
then 'Amoxicillin'
end) as Amoxicillin ,
(case when [description_of_what_happened] like '%Atorvastatin%'
then 'Atorvastatin'
end
) as Atorvastatin
from "NAME OF TABLE"
where Amoxicillin is not null or Atorvastatin is not null
group by grouping sets ((), (Amoxicillin), (Atorvastatin))
order by name;
Note that I also moved the logic in the having to the where.
I have a table where the id field (not a primary key) contains either 1 or null. Over the past several years, any given part could have been entered multiple times with one, or both of these possible options.
I'm trying to write a statement that will return some value if there is ever a 1 associated with the select statement. There are lots of semi-duplicate rows, some with 1 and some with null, but if there is ever a 1, I want to return true, and if there are only null values, I want to return false. I'm not sure how to code this though.
If this is my SELECT part,id from table where part = "ABC1234" statement
part id
ABC1234 1
ABC1234 null
ABC1234 null
ABC1234 null
ABC1234 1
I want to write a statement that returns true, because 1 exists in at least one of these rows.
The closest I've come to this is by using a CASE statement, but I'm not quite there yet:
SELECT
a1.part part,
CASE WHEN a2.id is not null
THEN
'true'
ELSE
'false'
END AS id
from table.parts a1, table.ids a2 where a1.part = "ABC1234" and a1.key = a2.key;
I also tried the following case:
CASE WHEN exists
(SELECT id from table.ids where id = 1)
THEN
but I got the error subqueries are not supported in the select list
For the above SELECT statement, how do I return 1 single line that reads:
part id
ABC1234 true
You can use conditional aggregation to check if a part has atleast one row with id=1.
SELECT part,'True' id
from parts
group by part
having count(case when id = 1 then 1 end) >= 1
To return false when the id's are all nulls use
select part, case when id_true>=1 then 'True'
when id_false>=1 and id_true=0 then 'False' end id
from (
SELECT part,
count(case when id = 1 then 1 end) id_true,
count(case when id is null then 1 end) id_false,
from parts
group by part) t
This question already has answers here:
Return a value if no record is found
(6 answers)
Get 0 value from a count with no rows
(6 answers)
Closed 7 years ago.
I have a simple query:
Select qty from X where id=....;
this query always return 0 or 1 row.
when it return 1 row everything works.
but if it return 0 rows my query fails as qty is used in calculations. (This is acatually a Sub query in Select statment).
I need somehow to make sure the query always return 1 row.
I tried:
Select coalesce(qty,0) from X where id=....;
but it doesn't help as if there are no rows the coalesce is useless.
if no row found it should give 0
How can I fix it?
You can do this:
SELECT COALESCE( (SELECT qty from X where id=....), 0)
if nothing is returned from the inner SELECT statement, COALESCE will give you 0 in the outer SELECT statement.
Select *.a from (
Select qty, 0 as priority from X where id=....
Union
Select 0, 1 as priority
) a
Order By a.priority Asc
Limit 1
This select basically ensures that at least one row is returned by adding an additional row to the end and by adding the limit statement we just return the first row.
So now there is the case where at least one row is found and the additional row is added to the end. In this case the first row found (see ->) will be returned due to the ascending order by priority:
qty priority
-> 1 0
3 0
4 0
. .
0 1
And then there is the case where no row is found but the additional row is returned:
qty priority
-> 0 1
try this.
SELECT COALESCE((SELECT qty
FROM x
WHERE id = #MyIdVar), 1)
If no records found then its return 'No rows found'
if not exists(Select * from table where condition=...)
Begin
Select * from table where condition=...
End
Else
Begin
Select 'No rows found'
End
Whenever you use this you will get record else no record found message.
Without using COALESCE()
select qty from X where id=1 UNION SELECT 0 order by qty desc limit 1
Demo
Assume we have the table as follows,
id Col-1 Col-2
A 1 some text
B 0 some other text
C 3
...
Take the table above as example, I want to build one SQL statement which would output the result: 2, 2.
The first value is the avg of all col-1 values except for 0, that is (1+3)/2 = 2. (If 0 is counted, then the result would be (1+0+3)/3 = 1, which is not what I want.)
The second value is the total number of all col-2 that is not empty. So the value is 2.
P.S, I know how to create them separately. What I prefer is to create only 1 statement to get both results.
For the first you can use NULLIF as null values are ignored in aggregations such as AVG.
For the second I assume you want to only count values not NULL or empty string.
SELECT AVG(NULLIF(Col1, 0)),
COUNT(CASE WHEN Col2 <> '' THEN 1 END)
FROM T
You want conditional aggregation:
select avg(case when col1 <> 0 then col1 end) as avg_not_zero,
count(col2) as num_not_empty
from table t;
As a note: 0 does not mean that the value is empty. Often NULL is used for this purpose in SQL, although strictly speaking, NULL means an unknown value.
Note: If "empty" could mean the empty string instead of NULL:
select avg(case when col1 <> 0 then col1 end) as avg_not_zero,
count(nullif(col2, '')) as num_not_empty
from table t;