I am using a MySql table with 500,000 records. The table contains a field (abbrevName) which stores a two-character representation of the first two letters on another field, name.
For example AA AB AC and so on.
What I want to achieve is the set the value of another field (pgNo) which stores a value for page number, based on the value of that records abbrevName.
So a record with an abbrevName of 'AA' might get a page number of 1, 'AB' might get a page number of 2, and so on.
The catch is that although multiple records may have the same page number (after all multiple entities might have a name beginning with 'AA'), once the amount of records with the same page number reaches 250, the page number must increment by one. So after 250 'AA' records with a page number of 1, we must assign futher 'AA records with a page number of 2, and so on.
My Pseudocode looks something like this:
-Count distinct abbrevNames
-Count distinct abbrevNames with more than 250 records
-For the above abbrevNames count the the sum of each divided by 250
-Output a temporary table sorted by abbrevName
-Use the total number of distinct page numbers with 250 or less records to assign page numbers incrementally
I am really struggling to put anything together in a query that comes close to this, can anyone help with my logic or some code ?
Please have a try with this one:
SELECT abbrevNames, CAST(pagenumber AS signed) as pagenumber FROM (
SELECT
abbrevNames
, IF(#prev = abbrevNames, #rows_per_abbrev:=#rows_per_abbrev + 1, #pagenr:=#pagenr + 1)
, #prev:=abbrevNames
, IF(#rows_per_abbrev % 250 = 0, #pagenr:=#pagenr + 1, #pagenr) AS pagenumber
, IF(#rows_per_abbrev % 250 = 0, #rows_per_abbrev := 1, #rows_per_abbrev)
FROM
yourTable
, (SELECT #pagenr:=0, #prev:=NULL, #rows_per_abbrev:=0) variables_initialization
ORDER BY abbrevNames
) subquery_alias
UPDATE: I had misunderstood the question a bit. Now it should work
Related
I have a table with a column called "Points", the value of this column have a min value of 0, and a max value of 100.000. I have to do an analysis per range of this column, so I wrote a query like this:
select case when Points between 0 and 5000 then '0 - 5000'
when Points between 5001 and 20000 then '50001 - 20000'
when Points > 20000 then '> 20000'
else 0 end RangeP
from Sales
The problem is that the customer wants to see for each 2.000 points from 0 to 100.000
If I wrote the query using the case, the query will get really big, so I'd like one way to get dynamically this range.
It is possible? Thank you very much
You may create a table which contains the ranges, and their text labels, and then join to it, e.g.
SELECT
s.Points,
COALESCE(r.label, 'range not found') AS range
FROM Sales s
LEFT JOIN
(
SELECT 0 AS start, 2000 AS end, '0 - 2000' AS label UNION ALL
SELECT 2001, 4000, '2001 - 4000' UNION ALL
...
SELECT 98000, 100000, '98000 - 100000'
) r
ON s.Points BETWEEN r.start AND r.end;
I have inlined the table of ranges, but you may create a formal table (or maybe a temp table) instead, and then replace the above subquery with just a reference to that table.
I have a data set like that:
Data Set Contents
From To Comment
----+---+--------
0 50 Bad
50 70 Good
70 100 Excellent
If I have a value of 75, I need to get Excellent by searching the Dataset.
I know about the lookup function but it is not what I want. How can I do that?
The values should be in percentage.
Note : the value (75) is Average of a column (Calculated) it
calculate student grade from max and student mark Version SQL Server
2016
Note 2 : the dataset is from database not static values
Thank You
Assuming you only ever have a fixed number of 'grades' then this will work. However, I would strongly recommend doing this type of work on the server where possible.
Here we go...
I created two datasets
dsGradeRange with the following sql to recreate your example (more or less)
DECLARE #t TABLE (low int, high int, comment varchar(20))
INSERT INTO #t VALUES
(0,49,'Bad'),
(50,69,'Good'),
(70,100, 'Excellent')
SELECT * FROM #t
dsRandomNumbers This just creates 30 random numbers between 0 and 100
SELECT *
FROM (SELECT top 30 ABS(CHECKSUM(NEWID()) % 100) as myNumber FROM sys.objects) x
ORDER BY myNumber
I added a table to the report to show the grades (just for reference).
I then added a table to show the dsRandomNumbers
Finally I set the expression of the 2nd column to the following expression.
=SWITCH
(
Fields!myNumber.Value < LOOKUP("Bad", Fields!comment.Value, Fields!high.Value, "dsGradeRange"), "Bad",
Fields!myNumber.Value < LOOKUP("Good", Fields!comment.Value, Fields!high.Value, "dsGradeRange"), "Good",
True, "Excellent"
)
This gives the following results
As you can see we only need to compare to the high value of each case, the first match will return the correct comment.
Right click on your dataset and add a calculated field. Go to Field Properties > Fields > Add and add the following expression, which descripes your scenario:
=IIF(Fields!Number.Value < 50, "Bad", "Good")
I have a SQL table with periodic measurements. I'd like to be able to return some summary method (say SUM) over the value column, for an arbitrary number of rows at a time. So if I had
id | reading
1 10
5 14
7 10
11 12
13 18
14 16
I could sum over 2 rows at a time, getting (24, 22, 34), or I could sum 3 rows at a time and get (34, 46), if that makes sense. Note that the ID might not be contiguous -- I just want to operate by row count, in sort order.
In the real world, the identifier is a timestamp, but I figure that (maybe after applying a unix_timestamp() call) anything that works for the simple case above should be applicable. If it matters, I'm trying to gracefully scale the number of results returned for a plot query -- maybe there's a smarter way to do this? I'd like the solution to be general, and not impose a particular storage mechanism/schema on the data.
You may resequense query result and then group it
SET #seq = 0;
SELECT SUM(data), ts FROM (
SELECT #seq := #seq + 1 AS seq, data, ts FROM table ORDER BY ts LIMIT 50
) AS tmp GROUP BY floor(tmp.seq / 3);
I'm having trouble with this SQL:
$sql = mysql_query("SELECT $menucompare ,
(COUNT($menucompare ) * 100 / (SELECT COUNT( $menucompare )
FROM data WHERE $ww = $button )) AS percentday FROM data WHERE $ww >0 ");
$menucompare is table fields names what ever field is selected and contains data bellow
$button is the week number selected (lets say week '6')
$ww table field name with row who have the number of week '6'
For example, I have data in $menucompare like that:
123456bool
521478bool
122555heel
147788itoo
and I want to select those, who have same word in the last of the data and make percentage.
The output should be like that:
bool -- 50% (2 entries)
heel -- 25% (1 entry)
itoo -- 25% (1 entry)
Any clearness to my SQL will be very appreciated.
I didn't find anything like that around.
Well, keeping data in such format probably not the best way, if possible, split the field into 2 separate ones.
First, you need to extract the string part from the end of the field.
if the length of the string / numeric parts is fixed, then it's quite easy;
if not, you should use regular expressions which, unfortunately, are not there by default with MySQL. There's a solution, check this question: How to do a regular expression replace in MySQL?
I'll assume, that numeric part is fixed:
SELECT s.str, CAST(count(s.str) AS decimal) / t.cnt * 100 AS pct
FROM (SELECT substr(entry, 7) AS str FROM data) AS s
JOIN (SELECT count(*) AS cnt FROM data) AS t ON 1=1
GROUP BY s.str, t.cnt;
If you'll have regexp_replace function, then substr(entry, 7) should be replaced to regexp_replace(entry, '^[0-9]*', '') to achieve the required result.
Variant with substr can be tested here.
When sorting out problems like this, I would do it in two steps:
Sort out the SQL independently of the presentation language (PHP?).
Sort out the parameterization of the query and the presentation of the results after you know you've got the correct query.
Since this question is tagged 'SQL', I'm only going to address the first question.
The first step is to unclutter the query:
SELECT menucompare,
(COUNT(menucompare) * 100 / (SELECT COUNT(menucompare) FROM data WHERE ww = 6))
AS percentday
FROM data
WHERE ww > 0;
This removes the $ signs from most of the variable bits, and substitutes 6 for the button value. That makes it a bit easier to understand.
Your desired output seems to need the last four characters of the string held in menucompare for grouping and counting purposes.
The data to be aggregated would be selected by:
SELECT SUBSTR(MenuCompare, -4) AS Last4
FROM Data
WHERE ww = 6
The divisor in the percentage is the count of such rows, but the sub-stringing isn't necessary to count them, so we can write:
SELECT COUNT(*) FROM Data WHERE ww = 6
This is exactly what you have anyway.
The divdend in the percentage will be the group count of each substring.
SELECT Last4, COUNT(Last4) * 100.0 / (SELECT COUNT(*) FROM Data WHERE ww = 6)
FROM (SELECT SUBSTR(MenuCompare, -4) AS Last4
FROM Data
WHERE ww = 6
) AS Week6
GROUP BY Last4
ORDER BY Last4;
When you've demonstrated that this works, you can re-parameterize the query and deal with the presentation of the results.
Brain is not working today and my google skills are failing me.
I have a column of numbers ranging from 1 - 1000. I want to dump the min and max values for 100 (or whatever I chose) record ranges into a temp table. The plan is to use this temp table to process ranges of records (in this example 100 at a time) in a larger table.
Swear I have done this before with a CTE but then I had something to group on. Here I just want to break up a single list of numbers into ranges of X.
The output from the temp table should look like:
Min Max
0 99
100 199
200 299
300 399
etc.
Thanks!
You can use this trick from Stuart Ainsworth:
http://codegumbo.com/index.php/2009/01/25/building-ranges-using-a-dynamically-generated-numbers-table/
Numbers tables are awesome, but he uses a dynamically generated numbers table, which is even awesome...r.
If you know all numbers are present in the source table, you can use a recursive CTE to generate the number ranges:
; with numbers as
(
select 0 as a
, 99 as b
union all
select a+100
, b+100
from numbers
where a < 900
)
select *
from numbers
If the source table is sparsely populated, you can limit it to numbers that are actually present like:
... insert CTE from above here ...
select min(ot.NumberColumn)
, max(ot.NumberColumn)
from numbers
left join
OtherTable ot
on ot.NumberColumn between numbers.a and numbers.b
group by
numbers.a
enter code hereI have been having a play with a CTE after you posted this and came up with the following, I would be interested to hear if it works for you at all.
DECLARE #segment int = 100
;
WITH _CTE
(rowNum, value)
AS
(
SELECT ROW_NUMBER() OVER(ORDER BY col01) -1, col01
FROM dbo.testTable
)
SELECT rowNum/#segment AS Bucket, MIN(Value) AS MinVal, MAX(Value) AS MaxVal
FROM _CTE
group by rowNum/#segment
ORDER BY Bucket
;
col01 in this case is the column that you want the min/max range values from, as is TestTable.