On the same row I have dulpicate data.
I have columns aCust, bCust, aPart, bPart, aSM, bSM, aSales, bSales.
I want to combine the Cust together, parts together, and SM together while keeping Sales separate. Some rows have data in both a and b, some a's are null and some b's are null. How do I combine this? If there is data in both a and b, it is always identical (except for sales).
Try this query. It looks weird but will do the job. You didn't specify what RDBMS you're using (Oracle, MySQL, SQL Server, etc.). That's why I didn't use anything like ISNULL.
select
case when aCust is null then bCust else bCust end as Cust,
case when aPart is null then bPart else bPart end as Part,
case when aSM is null then bSM else bSM end as SM,
aSales, bSales
from
tbl
You can do this with coalesce():
select coalesce(aCust, bCust) as Cust,
coalesce(aPart, bPart) as Part,
coalesce(aSM, bSM) as SM,
aSales, bSales
from table;
This will choose the first non-NULL value to return for each field.
Related
SELECT
SP.SITE,
SYS.COMPANY,
SYS.ADDRESS,
SP.CUSTOMER,
SP.STATUS,
DATEDIFF(MONTH,SP.MEMBERSINCE, SP.EXPIRES) AS MONTH_COUNT
CASE WHEN(MONTH_COUNT = 0 THEN MONTH_COUNT = DATEDIFF(DAY,SP.MEMBERSINCE, SP.EXPIRES) AS DAY_COUNT)
ELSE NULL
END
FROM SALEPASSES AS SP
INNER JOIN SYSTEM AS SYS ON SYS.SITE = SP.SITE
WHERE STATUS IN (7,27,29);
I am still trying to understand SQL. Is this the right order to have everything? I'm assuming my datediff() is unable to work because it's inside case when. What I am trying to do, is get the day count if month_count is less than 1 (meaning it's less than one month and we need to count the days between the dates instead). I need month_count to run first to see if doing the day_count would even be necessary. Please give me feedback, I'm new and trying to learn!
Case is an expression, it returns a value, it looks like you should be doing this:
DAY_COUNT =
CASE WHEN DATEDIFF(MONTH,SP.MEMBERSINCE, SP.EXPIRES) = 0
THEN DATEDIFF(DAY,SP.MEMBERSINCE, SP.EXPIRES))
ELSE NULL END
You shouldn't actually need else null as NULL is the default.
Note also you [usually] cannot refer to a derived column in the same select
It appears that what you are trying to do is define the MonthCount column's value, and then reuse that value in another column's definition. (The Don't Repeat Yourself principle.)
In most dialects of SQL, you can't do that. Including MS SQL Server.
That's because SQL is a "declarative" language. This means that SQL Server is free to calculate the column values in any order that it likes. In turn, that means you're not allowed to do anything that would rely on one column being calculated before another.
There are two basic ways around that...
First, use CTEs or sub-queries to create two different "scopes", allowing you to define MonthCount before DayCount, and so reuse the value without retyping the definition.
SELECT
*,
CASE WHEN MonthCount = 0 THEN foo ELSE NULL END AS DayCount
FROM
(
SELECT
*,
bar AS MonthCount
FROM
x
)
AS derive_month
The second main way is to somehow derive the value Before the SELECT block is evaluated. In this case, using APPLY to 'join' a single value on to each input row...
SELECT
x.*,
MonthCount,
CASE WHEN MonthCount = 0 THEN foo ELSE NULL END AS DayCount
FROM
x
CROSS APPLY
(
SELECT
bar AS MonthCount
)
AS derive_month
In this query, I want to add a new column, which gives the SUM of a.VolumetricCharge, but only where PremiseProviderBillings.BillingCategory = 'Water'. But i don't want to add it in the obvious place since that would limit the rows returned, I only want it to get the new column value
SELECT b.customerbillid,
-- Here i need SUM(a.VolumetricCharge) but where a.BillingCategory is equal to 'Water'
Sum(a.volumetriccharge) AS Volumetric,
Sum(a.fixedcharge) AS Fixed,
Sum(a.vat) AS VAT,
Sum(a.discount) + Sum(deferral) AS Discount,
Sum(Isnull(a.estimatedconsumption, 0)) AS Consumption,
Count_big(*) AS Records
FROM dbo.premiseproviderbillings AS a WITH (nolock)
LEFT JOIN dbo.premiseproviderbills AS b WITH (nolock)
ON a.premiseproviderbillid = b.premiseproviderbillid
-- Cannot add a where here since that would limit the results and change the output
GROUP BY b.customerbillid;
Bit of a tricky one, as what you're asking for will definitely affect performance (your asking SQL Server to do more work after all!).
However, we can add a column to your results which performs a conditional sum so that it does not affect the result of the other columns.
The answer lies in using a CASE expression!
Sum(
CASE
WHEN PremiseProviderBillings.BillingCategory = 'Water' THEN
a.volumetriccharge
ELSE
0
END
) AS WaterVolumetric
I have a SQL query in which I am calculating a function cal(a,b) and performing subtraction like below
case
when a=1 and b=0 then case when (c -cal(a,b)) >0 then cal(a,b) else c end
end
In such a scenario, I have to call cal(a,b) twice which is costly.
Is there any way in oracle SQL such that I can store the value of this function
and it is pre-written SQL query so I can not use PL/SQL.
Depending on how you use your mentionned statement, you can have a table that stores such result, a new column that stores such result, in both cases, the values are either calculated "on demand", or calculated using a trigger. It may also be a materialized view that store such result of cal(a, b), but again, it depends how easy it is to obtain a and b, process and store, but also retrieve the result.
That being said, Oracle caching system is well-done and I'm not sure why Oracle would process cal(a, b) a second time if it was called with the same parameter in the same statement.
Use a subquery:
select t.*,
(case when a = 1 and b = 10and c > cal_11
then cal_11
end)
from (select t.*,
(case when a = 1 and b = 0 then cal(a, b) end) as cal11
from t
) t;
I have the below query. The problem is the last column productdesc is returning two records and the query fails because of distinct. Now i need to add one more column in where clause of the select query so that it returns one record. The issue is that the column i need
to add should not be a part of group by clause.
SELECT product_billing_id,
billing_ele,
SUM(round(summary_net_amt_excl_gst/100)) gross,
(SELECT DISTINCT description
FROM RES.tariff_nt
WHERE product_billing_id = aa.product_billing_id
AND billing_ele = aa.billing_ele) productdescr
FROM bil.bill_sum aa
WHERE file_id = 38613 --1=1
AND line_type = 'D'
AND (product_billing_id, billing_ele) IN (SELECT DISTINCT
product_billing_id,
billing_ele
FROM bil.bill_l2 )
AND trans_type_desc <> 'Change'
GROUP BY product_billing_id, billing_ele
I want to modify the select statement to the below way by adding a new filter to the where clause so that it returns one record .
(SELECT DISTINCT description
FROM RRES.tariff_nt
WHERE product_billing_id = aa.product_billing_id
AND billing_ele = aa.billing_ele
AND (rate_structure_start_date <= TO_DATE(aa.p_effective_date,'yyyymmdd')
AND rate_structure_end_date > TO_DATE(aa.p_effective_date,'yyyymmdd'))
) productdescr
The aa.p_effective_date should not be a part of GROUP BY clause. How can I do it? Oracle is the Database.
So there are multiple RES.tariff records for a given product_billing_id/billing_ele, differentiated by the start/end dates
You want the description for the record that encompasses the 'p_effective_date' from bil.bill_sum. The kicker is that you can't (or don't want to) include that in the group by. That suggests you've got multiple rows in bil.bill_sum with different effective dates.
The issue is what do you want to happen if you are summarising up those multiple rows with different dates. Which of those dates do you want to use as the one to get the description.
If it doesn't matter, simply use MIN(aa.p_effective_date), or MAX.
Have you looked into the Oracle analytical functions. This is good link Analytical Functions by Example
Ok, I have to put null values last. The query should run under Oracle and MySQL.
I've already came up with
ORDER BY
CASE WHEN some_table.ord IS NULL THEN 9999999999 ELSE some_table.ord END
I should use value > max(some_table.ord) instead of 9999999999.
I think subquery to determine this value is too ugly here.
If this was C++ I can use some macro like INT_MAX for this purpose. Can you name its cross-DBMS SQL twin?
UPDATE
the question is if can I put something .. beautiful instead of 9999999999, so that query will work both in Oracle and MySQL,
not how to put null values last
Use an extra column for the null flag:
order by
case when some_table.ord is null then 2 else 1 end ,
some_table.ord
Or, if you have enough knowledge of the values that this column can take, just hard-code a number that is larger than anything in there:
order by coalesce(some_table.ord, 9999999999)
In Oracle, it's simply
ORDER BY some_table.ord NULLS LAST
Something like the following might work:
SELECT S.VAL1, S.VAL2, S.VAL3, COALESCE(S.ORD, O.MAX_ORD+1) AS ORD
FROM SOME_TABLE S,
(SELECT MAX(ORDER) AS MAX_ORD FROM SOME_TABLE) O
WHERE S.whatever = whichever AND
S.something <> something_else
ORDER BY ORD
Not sure if MySQL allows sub-queries in the FROM list. The idea here is to avoid the use of a magic value to handle the NULL case.
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