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I have a long expression which may return a positive, negative or zero decimal value. I would like to do this:
SELECT CASE WHEN {long expression} < 0 THEN 0 ELSE {long expression} END
But I don't want to repeat the long expression. I would like something like ISNULL, such as
SELECT ISNEGATIVE({long expression}, 0)
But that doesn't seem to be a thing. Obviously GREATER would work but it's 2017.
I'm pretty sure I'm hosed, but was hoping for a miracle. Anyone?
Consider using a CROSS APPLY. They will allow you to reference aliases and stack calculations
Select CASE WHEN AVAL < 0 THEN 0 ELSE AVAL END
From YourTable A
Cross Apply ( values (longexpression) )B(AVAL)
Just for some variety...
You could round trip it through FORMAT as this allows positive values, negative values and zeroes to be treated differently.
SELECT CAST(FORMAT({long expression}, '#.########;\0;0') AS DECIMAL(18,8))
I'd just use the APPLY myself though as first port of call (rather than gratuitously calling a known slow function unnecessarily with some completely unwarranted string casting).
A CTE could be a good fit here. Something like:
with cte as (
select *,
longExpression = «long expression definition here»
from yourTable
)
select «other stuff»,
CASE WHEN longExpression < 0 THEN 0 ELSE longExpression END
from cte;
I want to slice a word eg: SMILE into :
S
M
I
L
E
I did it like this
SEL SUBSTR(EMP_NAME,1,1) FROM etlt5.employe where EMP_ID='28008'
UNION ALL
SEL SUBSTR(EMP_NAME,2,1) FROM etlt5.employe where EMP_ID='28008'
UNION ALL
SEL SUBSTR(EMP_NAME,3,1) FROM etlt5.employe where EMP_ID='28008'
I also tried it with recursive query but no final results.is there a better way of doing this because this looks more like a hardcoded one.
You could use STRTOK_SPLIT_TO_TABLE to do this. STRTOK_SPLIT_TO_TABLE splits a field by a delimiter and then takes each token (stuff between the delimiter) and sticks it in it's own record of a new derived table.
In your case you don't have a delimiter between the characters of "SMILE" so we can use some REGEXP_REPLACE magic to stick a comma between each letter, and then split that to a table:
WITH test (id, word) AS (SELECT 1, 'SMILE')
SELECT D.*
FROM TABLE (strtok_split_to_table(test.id, REGEXP_REPLACE(test.word, '([a-zA-Z])', ',\1'), ',')
RETURNS
( id integer
, rownum integer
, new_col varchar(100)character set unicode)
) as d
I've used this STRTOK_SPLIT_TO_TABLE(REGEXP_REPLACE()) before to split apart document numbers in order to determine a check digit, so it definitely has its uses.
May I ask why you want to do that?
You need a table with a sequence from 1 to the max length of EMP_NAME:
select SUBSTR(EMP_NAME,n,1)
FROM etlt5.employe CROSS JOIN number_table
where EMP_ID='28008'
select top 1 #arastr = k
from #m
where datalength(k) = (select max(datalength(k)) from #m)
What does this query do, and what is the point of select top 1 #arastr = k? This query is taken from a stored procedure which has been working for 7-8 years, so there is nothing wrong with the query, but I could not understand what it does.
(#m is a temp table which is created in the early part of the query.)
The query select one random value (since top is used without an order by clause) from the column k in the temporary table #m and assigns it to a variable #arastr (which has been previously declared supposedly). The string selected will be any matching the longest (measured in bytes (by the datalength function)) string in the table.
This is a quite common (but a little old fashioned) way to get the value of k into the (previously declared!) variable #arastr for later usage.
The function DATALENGTH will measure the length of e.g. a VARCHAR.
With TOP 1 you geht in any case only one result row, the one with the "longest" k, it's value is in #arastr afterwards...
EDIT: As pointed out by #jpw this will be random, if there is more than one k with the same (longest) length.
Without knowing, what #m looks like and what kind of data is in 'k' I cannot tell you any more.
probably makes more sense if it looks like this
SET #arastr = (SELECT TOP 1 k
FROM #m
WHERE DATALENGTH(k) = (SELECT MAX(DATALENGTH(k)) FROM #m))
I have following query
Select
a,b,c,
case totalcount
when 0 then 0
else abcd/totalcount
end AS 'd',
case totalcount
when 0 then 0
else defg/totalcount
end AS 'e'
From
Table1
In this query, I have same case statement in select query...Can i make it into single select statement.
"totalcount" is some value... abcd and defg are two column values from table1. If totalcount is zero, i dont want to divide, else I wish to divide to get an average value of abcd and defg.
No, since you seem to be requiring two output columns in your desired resultset... Each Case statement can generate at most one output value.
It doesn't matter how many columns the case statement needs to access to do it's job, or how many different values it has to select from (how many When... Then... expressions), it just matters how many columns you are trying to generate in the final resultset.
At first view, I would say no, since you seem to use the exact same condition leading to different results.
Besides, this looks odd to me, why would you need two SELECT CASE for only one condition? This makes no sense.
Could you be more specific or give a real-world example of what you're trying to ask, with "real" data so that we might better answer your question?
EDIT #1
Given that:
Yes...it's two different fields....and the valud i need is calculated one...which is Value = a/b. But i need to check if b is zero or not
I would still answer no, as if they are two different fields, and you want both results in your result set, then you will need to write two CASE statements, one for each of the fields you need to verify whether it is zero-valued or not. Keep in mind that one CASE statement is equivalent to one single column only. So, if you need to check for a zero value, you are required to check for both independently.
By the way, sorry for my misunderstanding, that must be a language barrier, unfortunately. =) But my requirement for "real" data example holds, since this might light us all up with some other related solutions, we never know! =)
EDIT #2
Considering you have to check for a value of 0, I would perhaps rewrite my code as follows, for the sake of readability:
select a, b, c
, case when condition1 <> 0 then abcd / condition1 else 0 end as Result1
, case when condition2 <> 0 then defg / condition2 else 0 end as Result2
from Table1
In my opinion, it is leaner and swifter in the code, and it is easier to understand what is the intention. But after all, the result would be the same! No offense made here! =)
EDIT #3
After having read your question edit:
"totalcount" is some value... abcd and defg are two column values from table1. If totalcount is zero, i dont want to divide, else I wish to divide to get an average value of abcd and defg.
I say, if it is the average that you're after, why not just use the AVG function which will deal with it internaly, without having to care about zero values?
select a, b, c
, AVG(abcd) as Result1
, AVG(defg) as Result2
from Table1
Plus, considering having no record, the average can only be 0!
I don't know about your database engine, but if it is Oracle or SQL Server, and I think DB2 as well, they support this function.
You need to elaborate more - what is the condition? With what you have entered so far, it looks like you are just using the result of the expression, making the CASE statement redundant.
For example, see my inline comments:
SELECT a,b,c,
case condition
when 0 then 0 --this is unnecessary
else abcd/condition, --this is just using the result of the condition?
case condition
when 0 then 0 --this is unnecessary
else defg/condition --this is just using the result of the condition?
from Table1
so you could just refactor this as:
SELECT a
,b
,c
,expression
,expression
from Table1
if you actually meant the else abcd/condition as evaluate another condition or use a default value then you need to expand on that so we can answer accurately.
EDIT: if you are looking to avoid a divide by zero and you only want to evaluate condition once, then you need to do it outside of the SELECT and use the variable inside the SELECT. I wouldn't be concerned about the performance impact of evaluating it multiple times, if the condition doesn't change then its value should be cached by the query execution engine. Although it could look ugly and unmaintainable, in which case you could possibly factor condition into a function.
If all you're trying to do is avoid dividing by zero, and if it's not critical that an attempt to divide by zero actually produces zero, then you can do the following:
Select
a,b,c,
abcd / NULLIF(totalcount,0) AS 'd',
defg / NULLIF(totalcount,0) AS 'e'
From
Table1
This transforms an attempt to divide by zero into an attempt to divide by NULL, which always produces NULL.
If you need zero and you know that abcd and defg will never be NULL, then you can wrap the whole thing in an ISNULL(...,0) to force it to be zero. If abcd or defg might legitimately be null and you need the zero output if totalcount is zero, then I don't know any other option than using a CASE statement, sorry.
Moreover, since it appears totalcount is an expression, for maintainability you could compute it in a subquery, such as:
Select
a,b,c,
abcd / NULLIF(totalcount,0) AS 'd',
defg / NULLIF(totalcount,0) AS 'e'
From
(
Select
a,b,c,
abcd,
defg,
(... expression goes here ...) AS totalcount
From
Table1
) Data
But if it's a simple expression this may be overkill.
Technically this is possible. I'm not suggesting it's a good idea though!
;with Table1 as
(
select 1 as a, 2 as b, 3 as c, 0 as condition, 1234 as abcd, 4567 AS defg UNION ALL
select 1 as a, 2 as b, 3 as c, 1 as condition, 1234.0 as abcd, 4567 AS defg
)
,
cte AS
(
Select
a,b,c,
case condition
when 0 then CAST(CAST(0 as decimal(18, 6)) as binary(9)) + CAST(CAST(0 as decimal(18, 6)) as binary(9))
else CAST(CAST(abcd/condition as decimal(18, 6)) as binary(9)) + CAST(CAST(defg/condition as decimal(18, 6)) as binary(9))
end AS d
From
Table1
)
Select
a,
b,
c,
cast(substring(d,1,9) as decimal(18, 6)) as d,
cast(substring(d,10,9) as decimal(18, 6)) as e
From cte
I am working with a table that comes from an external source, and cannot be "cleaned". There is a column which an nvarchar(20) and contains an integer about 95% of the time, but occasionally contains an alpha. I want to use something like
select * from sch.tbl order by cast(shouldBeANumber as integer)
but this throws an error on the odd "3A" or "D" or "SUPERCEDED" value.
Is there a way to say "sort it like a number if you can, otherwise just sort by string"? I know there is some sloppiness in that statement, but that is basically what I want.
Lets say for example the values were
7,1,5A,SUPERCEDED,2,5,SECTION
I would be happy if these were sorted in any of the following ways (because I really only need to work with the numeric ones)
1,2,5,7,5A,SECTION,SUPERCEDED
1,2,5,5A,7,SECTION,SUPERCEDED
SECTION,SUPERCEDED,1,2,5,5A,7
5A,SECTION,SUPERCEDED,1,2,5,7
I really only need to work with the
numeric ones
this will give you only the numeric ones, sorted properly:
SELECT
*
FROM YourTable
WHERE ISNUMERIC(YourColumn)=1
ORDER BY YourColumn
select
*
from
sch.tbl
order by
case isnumeric(shouldBeANumber)
when 1 then cast(shouldBeANumber as integer)
else 0
end
Provided that your numbers are not more than 100 characters long:
WITH chars AS
(
SELECT 1 AS c
UNION ALL
SELECT c + 1
FROM chars
WHERE c <= 99
),
rows AS
(
SELECT '1,2,5,7,5A,SECTION,SUPERCEDED' AS mynum
UNION ALL
SELECT '1,2,5,5A,7,SECTION,SUPERCEDED'
UNION ALL
SELECT 'SECTION,SUPERCEDED,1,2,5,5A,7'
UNION ALL
SELECT '5A,SECTION,SUPERCEDED,1,2,5,7'
)
SELECT rows.*
FROM rows
ORDER BY
(
SELECT SUBSTRING(mynum, c, 1) AS [text()]
FROM chars
WHERE SUBSTRING(mynum, c, 1) BETWEEN '0' AND '9'
FOR XML PATH('')
) DESC
SELECT
(CASE ISNUMERIC(shouldBeANumber)
WHEN 1 THEN
RIGHT(CONCAT('00000000',shouldBeANumber), 8)
ELSE
shouoldBeANumber) AS stringSortSafeAlpha
ORDEER BY
stringSortSafeAlpha
This will add leading zeros to all shouldBeANumber values that truly are numbers and leave all remaining values alone. This way, when you sort, you can use an alpha sort but still get the correct values (with an alpha sort, "100" would be less than "50", but if you change "50" to "050", it works fine). Note, for this example, I added 8 leading zeros, but you only need enough leading zeros to cover the largest possible integer in your column.