For those who run into this question twice; apologies. I'm trying to obtain the same answer using different code; I also posted this for obtaining M, powerquery or excel solutions.
I need to retrieve the nearest matching value in a fixed set values for an entire column.
The set of values that have to be matched looks as follows
| preceding column | Sys_size |
===============================
| ... | null |
| ... | 7 |
| ... | 9 |
| ... | 12 |
| ... | 15 |
| ... | 17 |
| ... | null |
so in short, the list above is variable (more sizes could be added or changed), and contains null values.
Second there's a bunch of variable numbers as follows
| preceding column | User_size |
================================
| ... | 8.5 |
| ... | 13 |
| ... | 6 |
| ... | 10.5 |
| ... | 18 |
| ... | 14 |
The result I want to obtain in my script looks like this
| preceding column | User_size | Sys_size |
===========================================
| ... | 8.5 | 9 |
| ... | 13 | 12 |
| ... | 6 | 7 |
| ... | 10.5 | 12 |
| ... | 18 | 17 |
| ... | 14 | 15 |
simply put, it searches the nearest Sys_size matching the User_size input. Note that in case the user's value falls exactly between two Sys_size values the result is rounded up.
So far I have achieved the inverted version of this which looks something along the lines of this, but only works with fixed value input:
SELECT DISTINCT Sys_Size
FROM System
WHERE ABS(Sys_Size - 8.5) = (
SELECT MIN(ABS(Sys_Size - 8.5))
FROM System
)
which would return 9
But this has to be systematically applied to the entire user column. I feel I'm ridiculously close and overlooking something very obvious.
In SQL Server, you can use apply:
select u.*, s.sys_size
from users u cross apply
(select top (1) u.*
from system s
where s.sys_size is not null
order by abs(s.sys_size - u.user_size)
) s;
two options the I know of
declare #U table (s decimal(5,2));
declare #S table (s decimal(5,2));
insert into #U values (7), (9), (12), (15), (17);
insert into #S values (8.5), (13), (6), (10.5), (18), (14);
select u.s, ss.s
from #U u
cross apply ( select top 1 s.s
from #S s
order by abs(u.s - s.s)
) ss;
select us, ss, diff
from
( select u.s as us, s.s as ss
, abs(s.s - u.s) as diff
, ROW_NUMBER() over (partition by u.s order by abs(s.s - u.s) asc) as rn
from #U u
cross join #S s
where u.s is not null and s.s is not null
) tt
where tt.rn = 1
order by us, rn
I want to know if there is a way to remove duplicate values from a table. The key 'distinct' will fetch us the unique rows however if one value differs in a column, it wont. so just wanted to know if this can be achieved by any means. Hope the below example will help.
For example : In the below table there are two entries for Emp_ID 1234 with two different priorities. my output should consider the higher priority row alone. Is it possible?
My table
+---------+------+--------+-------+
| Employee_ID| priority | gender |
+------------+-----------+--------+
| 1234 | 1 | F |
| 1234 | 10 | F |
| 5678 | 2 | M |
| 5678 | 25 | M |
| 9101 | 45 | F |
+------------+-----------+--------+
Output
+---------+------+--------+-------+
| Employee_ID| priority | gender |
+------------+-----------+--------+
| 1234 | 1 | F |
| 5678 | 2 | M |
| 9101 | 45 | F |
+------------+-----------+--------+
DELETE
FROM Table t
WHERE EXISTS ( SELECT Employee_ID FROM Table WHERE Employee_ID = t.Employee_ID AND priority < t.Priority)
That is if you really want to remove them from the table. The Exists part can also be used in a select query to leave the values in the Original table.
SELECT *
FROM Table t
WHERE NOT EXISTS (SELECT Employee_ID FROM Table WHERE Employee_ID = t.Employee_ID AND priority > t.Priority)
select Employee_ID,max(priority) as priority,gender
from table
group by Employee_ID,gender
I have a table like the following:
+-------+--------------+
| Value | Date |
+-------+--------------+
| 14 | 10/11/2010 |
| 12 | 10/12/2010 |
| 12 | 10/13/2010 |
| 10 | 10/14/2010 |
| 8 | 10/15/2010 |
| 6 | 10/16/2010 |
| 4 | 10/17/2010 |
| 2 | 10/18/2010 |
+-------+--------------+
I would like to calculate the return (the quotient) between every row and the last row (which is with the latest date). e.g for the row with date "10/16/2010", the result should be 6/2=3
Hence, the resulting table should be
+-------+--------------+
| result| Date |
+-------+--------------+
| 7 | 10/11/2010 |
| 6 | 10/12/2010 |
| 6 | 10/13/2010 |
| 5 | 10/14/2010 |
| 4 | 10/15/2010 |
| 3 | 10/16/2010 |
| 2 | 10/17/2010 |
| 1 | 10/18/2010 |
+-------+--------------+
Is it possible to complete this? thanks you!
You can get the value you want to divide by. Since that's always going to be a single row, you can just use a cross join to join to that and perform your division. SQL Fiddle
with maxdate as
(select max([Date]) as maxdate from table1),
divby as
(select
value as divby
from
table1
inner join maxdate md
on md.maxdate = table1.[date])
select
value / divby
,[date]
from
table1
cross join divby
To break it down a bit, the first CTE (cleverly named maxdate) gets the maximum date for the whole thing. The second CTE (divby) get the value (that you will be dividing by) for that max date. As long as you only get one row back from that, you can safely use a cross join, resulting in each row in your table being divided by that one value.
Another possible solution JOIN the the table to itself.
SQL Fiddle Example
select (t1b.value / t1a.value) as result,
t1b.date from table1 t1a
join table1 t1b on t1a.date = (select max(date) from table1)
Thanks for the fiddle, Andrew! Can be accomplished like this as well if 2008 and above (fiddle: http://sqlfiddle.com/#!3/ecda1/11):
SELECT [Value] / MIN([Value]) OVER () AS result,
[Date]
FROM Table1
I have been looking at CROSS / OUTER APPLY with a colleague and we're struggling to find real life examples of where to use them.
I've spent quite a lot of time looking at When should I use CROSS APPLY over INNER JOIN? and googling but the main (only) example seems pretty bizarre (using the rowcount from a table to determine how many rows to select from another table).
I thought this scenario may benefit from OUTER APPLY:
Contacts Table (contains 1 record for each contact)
Communication Entries Table (can contain a phone, fax, email for each contact)
But using subqueries, common table expressions, OUTER JOIN with RANK() and OUTER APPLY all seem to perform equally. I'm guessing this means the scenario isn't applicable to APPLY.
Please share some real life examples and help explain the feature!
Some uses for APPLY are...
1) Top N per group queries (can be more efficient for some cardinalities)
SELECT pr.name,
pa.name
FROM sys.procedures pr
OUTER APPLY (SELECT TOP 2 *
FROM sys.parameters pa
WHERE pa.object_id = pr.object_id
ORDER BY pr.name) pa
ORDER BY pr.name,
pa.name
2) Calling a Table Valued Function for each row in the outer query
SELECT *
FROM sys.dm_exec_query_stats AS qs
CROSS APPLY sys.dm_exec_query_plan(qs.plan_handle)
3) Reusing a column alias
SELECT number,
doubled_number,
doubled_number_plus_one
FROM master..spt_values
CROSS APPLY (SELECT 2 * CAST(number AS BIGINT)) CA1(doubled_number)
CROSS APPLY (SELECT doubled_number + 1) CA2(doubled_number_plus_one)
4) Unpivoting more than one group of columns
Assumes 1NF violating table structure....
CREATE TABLE T
(
Id INT PRIMARY KEY,
Foo1 INT, Foo2 INT, Foo3 INT,
Bar1 INT, Bar2 INT, Bar3 INT
);
Example using 2008+ VALUES syntax.
SELECT Id,
Foo,
Bar
FROM T
CROSS APPLY (VALUES(Foo1, Bar1),
(Foo2, Bar2),
(Foo3, Bar3)) V(Foo, Bar);
In 2005 UNION ALL can be used instead.
SELECT Id,
Foo,
Bar
FROM T
CROSS APPLY (SELECT Foo1, Bar1
UNION ALL
SELECT Foo2, Bar2
UNION ALL
SELECT Foo3, Bar3) V(Foo, Bar);
There are various situations where you cannot avoid CROSS APPLY or OUTER APPLY.
Consider you have two tables.
MASTER TABLE
x------x--------------------x
| Id | Name |
x------x--------------------x
| 1 | A |
| 2 | B |
| 3 | C |
x------x--------------------x
DETAILS TABLE
x------x--------------------x-------x
| Id | PERIOD | QTY |
x------x--------------------x-------x
| 1 | 2014-01-13 | 10 |
| 1 | 2014-01-11 | 15 |
| 1 | 2014-01-12 | 20 |
| 2 | 2014-01-06 | 30 |
| 2 | 2014-01-08 | 40 |
x------x--------------------x-------x
CROSS APPLY
There are many situation where we need to replace INNER JOIN with CROSS APPLY.
1. If we want to join 2 tables on TOP n results with INNER JOIN functionality
Consider if we need to select Id and Name from Master and last two dates for each Id from Details table.
SELECT M.ID,M.NAME,D.PERIOD,D.QTY
FROM MASTER M
INNER JOIN
(
SELECT TOP 2 ID, PERIOD,QTY
FROM DETAILS D
ORDER BY CAST(PERIOD AS DATE)DESC
)D
ON M.ID=D.ID
The above query generates the following result.
x------x---------x--------------x-------x
| Id | Name | PERIOD | QTY |
x------x---------x--------------x-------x
| 1 | A | 2014-01-13 | 10 |
| 1 | A | 2014-01-12 | 20 |
x------x---------x--------------x-------x
See, it generated results for last two dates with last two date's Id and then joined these records only in outer query on Id, which is wrong. To accomplish this, we need to use CROSS APPLY.
SELECT M.ID,M.NAME,D.PERIOD,D.QTY
FROM MASTER M
CROSS APPLY
(
SELECT TOP 2 ID, PERIOD,QTY
FROM DETAILS D
WHERE M.ID=D.ID
ORDER BY CAST(PERIOD AS DATE)DESC
)D
and forms he following result.
x------x---------x--------------x-------x
| Id | Name | PERIOD | QTY |
x------x---------x--------------x-------x
| 1 | A | 2014-01-13 | 10 |
| 1 | A | 2014-01-12 | 20 |
| 2 | B | 2014-01-08 | 40 |
| 2 | B | 2014-01-06 | 30 |
x------x---------x--------------x-------x
Here is the working. The query inside CROSS APPLY can reference the outer table, where INNER JOIN cannot do this(throws compile error). When finding the last two dates, joining is done inside CROSS APPLY ie, WHERE M.ID=D.ID.
2. When we need INNER JOIN functionality using functions.
CROSS APPLY can be used as a replacement with INNER JOIN when we need to get result from Master table and a function.
SELECT M.ID,M.NAME,C.PERIOD,C.QTY
FROM MASTER M
CROSS APPLY dbo.FnGetQty(M.ID) C
And here is the function
CREATE FUNCTION FnGetQty
(
#Id INT
)
RETURNS TABLE
AS
RETURN
(
SELECT ID,PERIOD,QTY
FROM DETAILS
WHERE ID=#Id
)
which generated the following result
x------x---------x--------------x-------x
| Id | Name | PERIOD | QTY |
x------x---------x--------------x-------x
| 1 | A | 2014-01-13 | 10 |
| 1 | A | 2014-01-11 | 15 |
| 1 | A | 2014-01-12 | 20 |
| 2 | B | 2014-01-06 | 30 |
| 2 | B | 2014-01-08 | 40 |
x------x---------x--------------x-------x
OUTER APPLY
1. If we want to join 2 tables on TOP n results with LEFT JOIN functionality
Consider if we need to select Id and Name from Master and last two dates for each Id from Details table.
SELECT M.ID,M.NAME,D.PERIOD,D.QTY
FROM MASTER M
LEFT JOIN
(
SELECT TOP 2 ID, PERIOD,QTY
FROM DETAILS D
ORDER BY CAST(PERIOD AS DATE)DESC
)D
ON M.ID=D.ID
which forms the following result
x------x---------x--------------x-------x
| Id | Name | PERIOD | QTY |
x------x---------x--------------x-------x
| 1 | A | 2014-01-13 | 10 |
| 1 | A | 2014-01-12 | 20 |
| 2 | B | NULL | NULL |
| 3 | C | NULL | NULL |
x------x---------x--------------x-------x
This will bring wrong results ie, it will bring only latest two dates data from Details table irrespective of Id even though we join with Id. So the proper solution is using OUTER APPLY.
SELECT M.ID,M.NAME,D.PERIOD,D.QTY
FROM MASTER M
OUTER APPLY
(
SELECT TOP 2 ID, PERIOD,QTY
FROM DETAILS D
WHERE M.ID=D.ID
ORDER BY CAST(PERIOD AS DATE)DESC
)D
which forms the following desired result
x------x---------x--------------x-------x
| Id | Name | PERIOD | QTY |
x------x---------x--------------x-------x
| 1 | A | 2014-01-13 | 10 |
| 1 | A | 2014-01-12 | 20 |
| 2 | B | 2014-01-08 | 40 |
| 2 | B | 2014-01-06 | 30 |
| 3 | C | NULL | NULL |
x------x---------x--------------x-------x
2. When we need LEFT JOIN functionality using functions.
OUTER APPLY can be used as a replacement with LEFT JOIN when we need to get result from Master table and a function.
SELECT M.ID,M.NAME,C.PERIOD,C.QTY
FROM MASTER M
OUTER APPLY dbo.FnGetQty(M.ID) C
And the function goes here.
CREATE FUNCTION FnGetQty
(
#Id INT
)
RETURNS TABLE
AS
RETURN
(
SELECT ID,PERIOD,QTY
FROM DETAILS
WHERE ID=#Id
)
which generated the following result
x------x---------x--------------x-------x
| Id | Name | PERIOD | QTY |
x------x---------x--------------x-------x
| 1 | A | 2014-01-13 | 10 |
| 1 | A | 2014-01-11 | 15 |
| 1 | A | 2014-01-12 | 20 |
| 2 | B | 2014-01-06 | 30 |
| 2 | B | 2014-01-08 | 40 |
| 3 | C | NULL | NULL |
x------x---------x--------------x-------x
Common feature of CROSS APPLY and OUTER APPLY
CROSS APPLY or OUTER APPLY can be used to retain NULL values when unpivoting, which are interchangeable.
Consider you have the below table
x------x-------------x--------------x
| Id | FROMDATE | TODATE |
x------x-------------x--------------x
| 1 | 2014-01-11 | 2014-01-13 |
| 1 | 2014-02-23 | 2014-02-27 |
| 2 | 2014-05-06 | 2014-05-30 |
| 3 | NULL | NULL |
x------x-------------x--------------x
When you use UNPIVOT to bring FROMDATE AND TODATE to one column, it will eliminate NULL values by default.
SELECT ID,DATES
FROM MYTABLE
UNPIVOT (DATES FOR COLS IN (FROMDATE,TODATE)) P
which generates the below result. Note that we have missed the record of Id number 3
x------x-------------x
| Id | DATES |
x------x-------------x
| 1 | 2014-01-11 |
| 1 | 2014-01-13 |
| 1 | 2014-02-23 |
| 1 | 2014-02-27 |
| 2 | 2014-05-06 |
| 2 | 2014-05-30 |
x------x-------------x
In such cases a CROSS APPLY or OUTER APPLY will be useful
SELECT DISTINCT ID,DATES
FROM MYTABLE
OUTER APPLY(VALUES (FROMDATE),(TODATE))
COLUMNNAMES(DATES)
which forms the following result and retains Id where its value is 3
x------x-------------x
| Id | DATES |
x------x-------------x
| 1 | 2014-01-11 |
| 1 | 2014-01-13 |
| 1 | 2014-02-23 |
| 1 | 2014-02-27 |
| 2 | 2014-05-06 |
| 2 | 2014-05-30 |
| 3 | NULL |
x------x-------------x
One real life example would be if you had a scheduler and wanted to see what the most recent log entry was for each scheduled task.
select t.taskName, lg.logResult, lg.lastUpdateDate
from task t
cross apply (select top 1 taskID, logResult, lastUpdateDate
from taskLog l
where l.taskID = t.taskID
order by lastUpdateDate desc) lg
To answer the point above knock up an example:
create table #task (taskID int identity primary key not null, taskName varchar(50) not null)
create table #log (taskID int not null, reportDate datetime not null, result varchar(50) not null, primary key(reportDate, taskId))
insert #task select 'Task 1'
insert #task select 'Task 2'
insert #task select 'Task 3'
insert #task select 'Task 4'
insert #task select 'Task 5'
insert #task select 'Task 6'
insert #log
select taskID, 39951 + number, 'Result text...'
from #task
cross join (
select top 1000 row_number() over (order by a.id) as number from syscolumns a cross join syscolumns b cross join syscolumns c) n
And now run the two queries with a execution plan.
select t.taskID, t.taskName, lg.reportDate, lg.result
from #task t
left join (select taskID, reportDate, result, rank() over (partition by taskID order by reportDate desc) rnk from #log) lg
on lg.taskID = t.taskID and lg.rnk = 1
select t.taskID, t.taskName, lg.reportDate, lg.result
from #task t
outer apply ( select top 1 l.*
from #log l
where l.taskID = t.taskID
order by reportDate desc) lg
You can see that the outer apply query is more efficient. (Couldn't attach the plan as I'm a new user... Doh.)
Here is an example as it is pretty difficult to explain:
Table one:
| Date | Place ID |
==========================
| 01-Feb-2013 | 1 |
| 21-Jun-2015 | 2 |
Table two:
| Place ID | Date Ranked | Score |
==================================
| 1 | 01-Jan-2012 | 2 |
| 1 | 01-Jan-2014 | 1 |
| 1 | 01-Jan-2010 | 3 |
| 2 | 01-Jan-2016 | 1 |
What I want to happen is with SQL (MS) is when the first record of table one is returned I want whatever the score at that time to be returned from the second table. So in this example the score should be 2 as it is after 01-Jan-2012 but before 01-Jan-2014. And when the second record from table 1 is returned it should return NULL or blank from table 2 as no score existed for that time chosen.
Hope that makes sense!!
In SQL Server, you can use outer apply:
select t1.*, t2.score
from table1 t1 outer apply
(select top 1 t2.*
from table2 t2
where t2.placeid = t1.placeid and
t2.dateranked <= t1.dateranked
order by t2.dateranked desc
) t2;
In this case, you can do the same thing with a correlated subquery as well.