I want to randomly pull out 3 records from a table and then order them to the field "sponsor_ranking".
My Code Reads.
$sql = "SELECT * FROM $TableSponsors ORDER BY RAND(), sponsor_ranking asc LIMIT 3";
But it is not ordering the results in order of the "sponsor_ranking" but it is randomizing the results.
Any suggestions?
Thank you.
Of course, ordering by sponsor_ranking is only useful if each of the records had the same RAND() value, which is not so likely.
You can solve it like this. Order by random, limit to 3, order again by sponsor_ranking.
SELECT * FROM
(SELECT * FROM $TableSponsors
ORDER BY RAND()
LIMIT 3) x
ORDER BY
sponsor_ranking
you could make a subtable in the for clause :
$sql = "SELECT * FROM (SELECT * FROM $TableSponsors ORDER BY RAND() LIMIT 3) Faketable ORDER BY sponsor_ranking";
This will never work. Doing an order by with multiple fields requires that the "earlier" fields have the same values for the second and subsequent fields to even be considered.
You'll have to use a subquery to do the rand() ordering, then rank by the other fields in the parent query:
SELECT *
FROM (
SELECT *
FROM $TableSponsors
ORDER BY RAND()
) as foo
ORDER BY sponsor_ranking
LIMIT 3
e.g. if your table had this:
x y
1 5
1 6
2 7
3 8
4 9
... ORDER BY x DESC, y ASC
then you'd get
x y
4 9 // only one "4", so 9 is ignored, no point in sorting a single value
3 8 // only one "3", so 8 is ignored, no point in sorting a single value
2 7 // ditto
1 5 // hey, there's two "1" values, so now the second field **IS** sorted
1 6
Related
I have a formula like this : =ArrayFormula(sort(INDEX($B$1:$B$10,MATCH(E1,$A$1:$A$10,0))))
in columns A:B:
a 1
b 2
c 3
d 4
e 5
f 6
g 7
h 8
i 9
j 10
and
the data to convert in E:H
a c f e
f a c b
b a c d
I get the following results using the above formula
in columns L:O:
1 3 6 5
6 1 3 2
2 1 3 4
My desired output is like this:
1 3 5 6
1 2 3 6
1 2 3 4
I'd like to arrange the numbers from smallest to biggest in value. I can do this with additional helper cells. but if possible i'd like to get the same result without any additional cells. can i get a little help please? thanks.
To sort by row, use SORT BYROW. But unfortunately, nested array results aren't supported in BYROW. So, we need to JOIN and SPLIT the resulting array.
=ARRAYFORMULA(SPLIT(BYROW(your_formula,LAMBDA(row,JOIN("🌆",SORT(TRANSPOSE(row))))),"🌆"))
Here's another way using Makearray with Index to get the current row and Small to get the smallest, next smallest etc. within the row:
=ArrayFormula(makearray(3,4,lambda(r,c,small(index(vlookup(E1:H3,A1:B10,2,false),r,0),c))))
Or you could change the order (might be a little faster) as you don't need to vlookup the entire array, just the current row:
=ArrayFormula(makearray(3,4,lambda(r,c,small(vlookup(index(E1:H3,r,0),A1:B10,2,false),c))))
It's interesting (to me at any rate) that you can interrogate the row and column number of the current cell using Map or Scan, so this is also possible:
=ArrayFormula(map(E1:H3,lambda(cell,small(vlookup(index(E1:H3,row(cell),0),A1:B10,2,false),column(cell)-column(E:E)+1))))
Thanks to #JvdV for this insight (which may be obvious to some but wasn't to me) shown here in Excel.
try:
=INDEX(TRIM(SPLIT(FLATTEN(QUERY(QUERY(QUERY(SPLIT(FLATTEN(E1:H3&"×​"&ROW(E1:H3)), "​"),
"select max(Col1) group by Col1 pivot Col2"), "offset 1", 0),,9^9)), "×")))
or if you want numbers:
=INDEX(IFNA(VLOOKUP(TRIM(SPLIT(FLATTEN(QUERY(QUERY(QUERY(SPLIT(FLATTEN(E1:H3&"×​"&ROW(E1:H3)), "​"),
"select max(Col1) group by Col1 pivot Col2"), "offset 1", 0),,9^9)), "×")), A:B, 2, 0)))
How do I select a random row from the database based on the probability chance assigned to each row.
Example:
Make Chance Value
ALFA ROMEO 0.0024 20000
AUDI 0.0338 35000
BMW 0.0376 40000
CHEVROLET 0.0087 15000
CITROEN 0.016 15000
........
How do I select random make name and its value based on the probability it has to be chosen.
Would a combination of rand() and ORDER BY work? If so what is the best way to do this?
You can do this by using rand() and then using a cumulative sum. Assuming they add up to 100%:
select t.*
from (select t.*, (#cumep := #cumep + chance) as cumep
from t cross join
(select #cumep := 0, #r := rand()) params
) t
where #r between cumep - chance and cumep
limit 1;
Notes:
rand() is called once in a subquery to initialize a variable. Multiple calls to rand() are not desirable.
There is a remote chance that the random number will be exactly on the boundary between two values. The limit 1 arbitrarily chooses 1.
This could be made more efficient by stopping the subquery when cumep > #r.
The values do not have to be in any particular order.
This can be modified to handle chances where the sum is not equal to 1, but that would be another question.
I have a data-set in which there are duplicate IDs in the first column. I'm hoping to obtain a single row of data for each ID based on the second column's value. The data looks like so:
ID Info_Source Prior?
A 1 Y
A 3 N
A 2 Y
B 1 N
B 1 N
B 2 Y
C 2 N
C 3 Y
C 1 N
Specifically the criteria would call for prioritizing based on the second column's value (3 highest priority; then 1; and lastly 2): if the 'Info_Source' column has a value of 3, return that row; if there is no 3 in the second column for a given ID, look for a 1 and if found return that row; and finally if there is no 3 or 1 associated with the ID, search for 2 and return that row for the ID.
The desired results would be a single row for each ID, and the resulting data would be:
ID Info_Source Prior?
A 3 N
B 1 N
C 3 Y
row_number() over() usually solves these needs nicely and efficiently e.g.
select ID, Info_Source, Prior
from (
select ID, Info_Source, Prior
, row_number() over(partition by id order by Info_source DESC) as rn
)
where rn = 1
For prioritizing the second column's value (3 ; then 1, then 2) use a case expression to alter the raw value into an order that you need.
select ID, Info_Source, Prior
from (
select ID, Info_Source, Prior
, row_number() over(partition by id
order by case when Info_source = 3 then 3
when Infor_source = 1 then 2
else 1 end DESC) as rn
)
where rn = 1
I have following 2 recordsets :
Recordset 1:
Id isVal isVal1
1 Y N
2 Y N
Recordset 2:
Id isVal isVal1
2 N Y
3 N Y
Actual recordset required is:
Id isVal isVal1
1 Y N
2 Y Y
3 N Y
Should I use join? Can you please advice me how can I solve this?
No, you want to place the records on top of each other so you would need to use union.
select id, max(isval) as isval, max(isval1) as isval1
from ( select id, isval, isval1
from recordset1
union all
select id, isval, isval1
from recordset1
)
group by id
I use union all as you don't need to remove duplicates, for which you would remove the all.
The max works because 'Y' is "greater" than 'N'.
I'm assuming that 'Y' takes precedence over 'N' rather than values from the first record-set are less important than values from the second.
I had the following query:
SELECT nvl(sum(adjust1),0)
FROM (
SELECT
ManyOperationsOnFieldX adjust1,
a, b, c, d, e
FROM (
SELECT
a, b, c, d, e,
SubStr(balance, INSTR(balance, '[&&2~', 1, 1)) X
FROM
table
WHERE
a >= To_Date('&&1','YYYYMMDD')
AND a < To_Date('&&1','YYYYMMDD')+1
)
)
WHERE
b LIKE ...
AND e IS NULL
AND adjust1>0
AND (b NOT IN ('...','...','...'))
OR (b = '... AND c <> NULL)
I tried to change it to this:
SELECT nvl(sum(adjust1),0)
FROM (
SELECT
ManyOperationsOnFieldX adjust1
FROM (
SELECT
SubStr(balance, INSTR(balance, '[&&2~', 1, 1)) X
FROM
table
WHERE
a >= To_Date('&&1','YYYYMMDD')
AND a < To_Date('&&1','YYYYMMDD')+1
AND b LIKE '..'
AND e IS NULL
AND (b NOT IN ('..','..','..'))
OR (b='..' AND c <> NULL)
)
)
WHERE
adjust1>0
Mi intention was to have all the filtering in the innermost query, and only give to the outer ones the field X which is the one I have to operate a lot. However, the firts (original) query takes a couple of seconds to execute, while the second one won't even finish. I waited for almost 20 minutes and still I wouldn't get the answer.
Is there an obvious reason for this to happen that I might be overlooking?
These are the plans for each of them:
SELECT STATEMENT optimizer=all_rows (cost = 973 Card = 1 bytes = 288)
SORT (aggregate)
PARTITION RANGE (single) (cost=973 Card = 3 bytes = 864)
TABLE ACCESS (full) OF "table" #3 TABLE Optimizer = analyzed(cost=973 Card = 3 bytes=564)
SELECT STATEMENT optimizer=all_rows (cost = 750.354 Card = 1 bytes = 288)
SORT (aggregate)
PARTITION RANGE (ALL) (cost=759.354 Cart = 64.339 bytes = 18.529.632)
TABLE ACCESS (full) OF "table" #3 TABLE Optimizer = analyzed(cost=750.354 Card = 64.339 bytes=18.529.632)
Your two queries are not identical.
the logical operator AND is evaluated before the operator OR:
SQL> WITH data AS
2 (SELECT rownum id
3 FROM dual
4 CONNECT BY level <= 10)
5 SELECT *
6 FROM data
7 WHERE id = 2
8 AND id = 3
9 OR id = 5;
ID
----------
5
So your first query means: Give me the big SUM over this partition when the data is this way.
Your second query means: give me the big SUM over (this partition when the data is this way) or (when the data is this other way [no partition elimination hence big full scan])
Be careful when mixing the logical operators AND and OR. My advice would be to use brackets so as to avoid any confusion.
It is all about your OR... Try this:
SELECT nvl(sum(adjust1),0)
FROM (
SELECT
ManyOperationsOnFieldX adjust1
FROM (
SELECT
SubStr(balance, INSTR(balance, '[&&2~', 1, 1)) X
FROM
table
WHERE
a >= To_Date('&&1','YYYYMMDD')
AND a < To_Date('&&1','YYYYMMDD')+1
AND (
b LIKE '..'
AND e IS NULL
AND (b NOT IN ('..','..','..'))
OR (b='..' AND c <> NULL)
)
)
)
WHERE
adjust1>0
Because you have the OR inline with the rest of your AND statements with no parenthesis, the 2nd version isn't limiting the data checked to just the rows that fall in the date filter. For more info, see the documentation of Condition Precedence