I'm having some trouble figuring out any way to combine two SQL queries into a single one that expresses some greater idea.
For example, let's say that I have query A, and query B. Query A returns the total number of hours worked. Query B returns the total number of hours that were available for workers to work. Each one of these queries returns a single column with a single row.
What I really want, though, is essentially query A over query B. I want to know the percentage of capacity that was worked.
I know how to write query A and B independently, but my problem comes when I try to figure out how to use those prewritten queries to come up with a new SQL query that uses them together. I know that, on a higher level, like say in a report, I could just call both queries and then divide them, but I'd rather encompass it all into a single SQL query.
What I'm looking for is a general idea on how to combine these queries using SQL.
Thanks!
Unconstrained JOIN, Cartesian Product of 1 row by 1 row
SELECT worked/available AS PercentageCapacity
FROM ( SELECT worked FROM A ),
( SELECT available FROM B )
You can declare variables to store the results of each query and return the difference:
DECLARE #first INT
DECLARE #second INT
SET #first = SELECT val FROM Table...
SET #second = SELECT val FROM Table...
SELECT #first - #second
The answer depends on where the data is coming from.
If it's coming from a single table, it could be something as easy as:
select totalHours, availableHours, (totalHours - availableHours) as difference
from hoursTable
But if the data is coming from separate tables, you need to add some identifying column so that the rows can be joined together to provide some useful view of the data.
You may want to post examples of your queries so we know better how to answer your question.
You can query the queries:
SELECT
a.ID
a.HoursWorked/b.HoursAvailable AS UsedWork
FROM
( SELECT ID, HoursWorked FROM Somewhere ) a
INNER JOIN
( SELECT ID, HoursAvailable FROM SomewhereElse ) b
ON
a.ID = b.ID
Related
First time posting here, hopes it goes well.
I try to make a query with Oracle SQL Developer, where it returns a customer_ID from a table and the time of the payment from another. I'm pretty sure that the problems lies within my logicflow (It was a long time I used SQL, and it was back in school so I'm a bit rusty in it). I wanted to list the IDs as DISTINCT and ORDER BY the dates ASCENDING, so only the first date would show up.
However the returned table contains the same ID's twice or even more in some cases. I even found the same ID and same DATE a few times while I was scrolling through it.
If you would like to know more please ask!
SELECT DISTINCT
FIRM.customer.CUSTOMER_ID,
FIRM.account_recharge.X__INSDATE FELTOLTES
FROM
FIRM.customer
INNER JOIN FIRM.account
ON FIRM.customer.CUSTOMER_ID = FIRM.account.CUSTOMER
INNER JOIN FIRM.account_recharge
ON FIRM.account.ACCOUNT_ID = FIRM.account_recharge.ACCOUNT
WHERE
FIRM.account_recharge.X__INSDATE BETWEEN TO_DATE('14-01-01', 'YY-MM-DD') AND TO_DATE('14-12-31', 'YY-MM-DD')
ORDER
BY FELTOLTES
Your select works like this because a CUSTOMER_ID indeed has more than one X__INSDATE, therefore the records in the result will be distinct. If you need only the first date then don't use DISTINCT and ORDER BY but try to select for MIN(X__INSDATE) and use GROUP BY CUSTOMER_ID.
SELECT DISTINCT FIRM.customer.CUSTOMER_ID,
FIRM.account_recharge.X__INSDATE FELTOLTES
Distinct is applied to both the columns together, which means you will get a distinct ROW for the set of values from the two columns. So, basically the distinct refers to all the columns in the select list.
It is equivalent to a select without distinct but a group by clause.
It means,
select distinct a, b....
is equivalent to,
select a, b...group by a, b
If you want the desired output, then CONCATENATE the columns. The distict will then work on the single concatenated resultset.
I have two queries which return separate result sets, and the queries are returning the correct output.
How can I combine these two queries into one so that I can get one single result set with each result in a separate column?
Query 1:
SELECT SUM(Fdays) AS fDaysSum From tblFieldDays WHERE tblFieldDays.NameCode=35 AND tblFieldDays.WeekEnding=?
Query 2:
SELECT SUM(CHdays) AS hrsSum From tblChargeHours WHERE tblChargeHours.NameCode=35 AND tblChargeHours.WeekEnding=?
Thanks.
You can aliasing both query and Selecting them in the select query
http://sqlfiddle.com/#!2/ca27b/1
SELECT x.a, y.b FROM (SELECT * from a) as x, (SELECT * FROM b) as y
You can use a CROSS JOIN:
SELECT *
FROM ( SELECT SUM(Fdays) AS fDaysSum
FROM tblFieldDays
WHERE tblFieldDays.NameCode=35
AND tblFieldDays.WeekEnding=1) A -- use you real query here
CROSS JOIN (SELECT SUM(CHdays) AS hrsSum
FROM tblChargeHours
WHERE tblChargeHours.NameCode=35
AND tblChargeHours.WeekEnding=1) B -- use you real query here
You could also use a CTE to grab groups of information you want and join them together, if you wanted them in the same row. Example, depending on which SQL syntax you use, here:
WITH group1 AS (
SELECT testA
FROM tableA
),
group2 AS (
SELECT testB
FROM tableB
)
SELECT *
FROM group1
JOIN group2 ON group1.testA = group2.testB --your choice of join
;
You decide what kind of JOIN you want based on the data you are pulling, and make sure to have the same fields in the groups you are getting information from in order to put it all into a single row. If you have multiple columns, make sure to name them all properly so you know which is which. Also, for performance sake, CTE's are the way to go, instead of inline SELECT's and such. Hope this helps.
how to club the 4 query's as a single query
show below query
total number of cases pending + 2.cases filed during this month ( base on sysdate) + total number of cases (1+2) + no. cases disposed where nse= disposed + no. of cases pending (other than nse <> disposed)
nsc = nature of case
report is taken on 06th of every month
( monthly report will be counted from 05th previous month to 05th present of present month)
Given a relation R with n columns. Use sql to returns the tuples having the maximum number of occurrences of the values. I have no idea how to do query horizontally?
SELECT MAX(t.*) FROM mytable t
or
SELECT DISTINCT a, b, c FROM mytable
or
SELECT DISTINCT * FROM mytable
it depends on which SQL implementation you are referring to, and generally more information about the query. but the above examples should get you started so you can google some terms.
I'm not sure what you mean by querying horizontally. Is it one relation with multiple key columns linking the two tables? Sounds like you might just need to group by those columns and order by count(*) descending...
I have a question about how MS SQL evaluates functions inside CTEs. A couple of searches didn't turn up any results related to this issue, but I apologize if this is common knowledge and I'm just behind the curve. It wouldn't be the first time :-)
This query is a simplified (and obviously less dynamic) version of what I'm actually doing, but it does exhibit the problem I'm experiencing. It looks like this:
CREATE TABLE #EmployeePool(EmployeeID int, EmployeeRank int);
INSERT INTO #EmployeePool(EmployeeID, EmployeeRank)
SELECT 42, 1
UNION ALL
SELECT 43, 2;
DECLARE #NumEmployees int;
SELECT #NumEmployees = COUNT(*) FROM #EmployeePool;
WITH RandomizedCustomers AS (
SELECT CAST(c.Criteria AS int) AS CustomerID,
dbo.fnUtil_Random(#NumEmployees) AS RandomRank
FROM dbo.fnUtil_ParseCriteria(#CustomerIDs, 'int') c)
SELECT rc.CustomerID,
ep.EmployeeID
FROM RandomizedCustomers rc
JOIN #EmployeePool ep ON ep.EmployeeRank = rc.RandomRank;
DROP TABLE #EmployeePool;
The following can be assumed about all executions of the above:
The result of dbo.fnUtil_Random() is always an int value greater than zero and less than or equal to the argument passed in. Since it's being called above with #NumEmployees which has the value 2, this function always evaluates to 1 or 2.
The result of dbo.fnUtil_ParseCriteria(#CustomerIDs, 'int') produces a one-column, one-row table that contains a sql_variant with a base type of 'int' that has the value 219935.
Given the above assumptions, it makes sense (to me, anyway) that the result of the expression above should always produce a two-column table containing one record - CustomerID and an EmployeeID. The CustomerID should always be the int value 219935, and the EmployeeID should be either 42 or 43.
However, this is not always the case. Sometimes I get the expected single record. Other times I get two records (one for each EmployeeID), and still others I get no records. However, if I replace the RandomizedCustomers CTE with a true temp table, the problem vanishes completely.
Every time I think I have an explanation for this behavior, it turns out to not make sense or be impossible, so I literally cannot explain why this would happen. Since the problem does not happen when I replace the CTE with a temp table, I can only assume it has something to do with the functions inside CTEs are evaluated during joins to that CTE. Do any of you have any theories?
SQL Server's optimizer is free to decide whether to reevaluate a CTE or not.
For instance, this query:
WITH q AS
(
SELECT NEWID() AS n
)
SELECT *
FROM q
UNION ALL
SELECT *
FROM q
will produce two different NEWID()'s, however, if you use cached XML plan to wrap the CTE into an Eager Spool operation, the records will be same.
I'm doing a probability calculation. I have a query to calculate the total number of times an event occurs. From these events, I want to get the number of times a sub-event occurs. The query to get the total events is 25 lines long and I don't want to just copy + paste it twice.
I want to do two things to this query: calculate the number of rows in it, and calculate the number of rows in the result of a query on this query. Right now, the only way I can think of doing that is this (replace #total# with the complicated query to get all rows, and #conditions# with the less-complicated conditions that rows, from #total#, must have to match the sub-event):
SELECT (SELECT COUNT(*) FROM (#total#) AS t1 WHERE #conditions#) AS suboccurs,
COUNT(*) AS totaloccurs FROM (#total#) as t2
As you notice, #total# is repeated twice. Is there any way around this? Is there a better way to do what I'm trying to do?
To re-emphasize: #conditions# does depend on what #total# returns (it does stuff like t1.foo = bar).
Some final notes: #total# by itself takes ~250ms. This more complicated query takes ~300ms, so postgres is likely doing some optimization, itself. Still, the query looks terribly ugly with #total# literally pasted in twice.
If your sql supports subquery factoring, then rewriting it using the WITH statement is an option. It allows subqueries to be used more than once. With will create them as either an inline-view or a temporary table in Oracle.
Here is a contrived example.
WITH
x AS
(
SELECT this
FROM THERE
WHERE something is true
),
y AS
(
SELECT this-other-thing
FROM somewhereelse
WHERE something else is true
),
z AS
(
select count(*) k
FROM X
)
SELECT z.k, y.*, x.*
FROM x,y, z
WHERE X.abc = Y.abc
SELECT COUNT(*) as totaloccurs, COUNT(#conditions#) as suboccurs
FROM (#total# as t1)
Put the reused sub-query into a temp table, then select what you need from the temp table.
#EvilTeach:
I've not seen the "with" (probably not implemented in Sybase :-(). I like it: does what you need in one chunk then goes away, with even less cruft than temp tables. Cool.