I use SAP-HANA database. I have a simple 2 column table whose columns are number, name, noodles, fish . The rows are these:
number name noodles fish
1 tom x
1 tom x
1 jack
2 jack x
I would like to group the rows by the id, and concatenate the names into a field, and thus obtain this:
number name noodles fish
1 tom x x
2 jack x
Can you please tell me how we can perform this operation in sap-hana? Thanks in advance.
Well, you did not really concatenate the names, but instead kept the same ones (if you would have concatenated the names as well, you would get something like jackjack in your result). I guess your x's indicate some sort of ABAP-style flags.
In any case, you would do this with grouping. This is a completely non-HANA thing (you can use the same basic SQL for any DB). You can group against several columns. All other columns that you want to select must be used in an aggregated expression (e.g. a SUM, MAX, COUNT, etc.).
To get the output from your question, I wrote the following code:
SELECT "ID", "NAME", MAX("FISH"), MAX("NOODLES")
FROM #TEST GROUP BY "ID", "NAME";
And got the same output as you. I used the MAX function based on the following assumption: you would want to get X if there is any X in the "concatenated" (aggregated) rows in that column. You get nothing / space if all the "concatenated" rows have space in them.
Related
I am pulling data and when I pull in the text field my results for the "distinct ID" are sometimes being duplicated when there are multiple results for that ID. Is there a way to concatenate the results into a single column/row rather than having them duplicated?
It looks like there are ways in other SQL platforms but I have not been able to find something that works in HANA.
Example
Select
Distinct ID
From Table1
If I pull only Distinct ID I get the following:
ID
1
2
3
4
However when I pull the following:
Example
Select
Distinct ID,Text
From Table1
I get something like
ID
Text
1
Dog
2
Cat
2
Dog
3
Fish
4
Bird
4
Horse
I am trying to Concat the Text field when there is more than 1 row for each ID.
What I need the results to be (Having a "break" between results so that they are on separate lines would be even better but at least a "," would work):
ID
Text
1
Dog
2
Cat,Dog
3
Fish
4
Bird,Horse
I see Kiran has just referred to another valid answer in the comment, but in your example this would work.
SELECT ID, STRING_AGG(Text, ',')
FROM TABLE1
GROUP BY ID;
You can replace the ',' with other characters, maybe a '\n' for a line break
I would caution against the approach to concatenate rows in this way, unless you know your data well. There is no effective limit to the rows and length of the string that you will generate, but HANA will have a limit on string length, so consider that.
I have a column in PowerPivot that basically goes:
1
1
2
3
4
3
5
4
If I =AVERAGE([Column]), it's going to average all 8 values in the sample column. I just need the average of the distinct values (i.e., in the example above I want the average of (1,2,3,4,5).
Any thoughts on how to go about doing this? I tried a combination of =(DISTINCT(AVERAGE)) but it gives a formula error.
Thanks!!
Kevin
There must be a cleaner way of doing this but here is one method which uses a measure to get the sum of the values divided by the number of times it appears (to basically give the original value) then uses an iterative function to do it for each unique value.
Apologies for the uninspired measure names:
[m1] = SUM(table1[theValue]) / COUNTROWS(Table1)
[m2] = AVERAGEX(VALUES(Tables1[theValue]), [m1])
Assuming your table is caled table1 and the column is called theValue
I am using Oracle and I have a table with 1000 rows. There is a last name field and
I want to know the lengths of the name field but I don't want it for every row. I want a count of the various lengths.
Example:
lastname:
smith
smith
Johnson
Johnson
Jackson
Baggins
There are two smiths length of five. Four others, length of seven. I want my query to return
7
5
If there were 1,000 names I expect to get all kinds of lengths.
I tried,
Select count(*) as total, lastname from myNames group by total
It didn't know what total was. Grouping by lastname just groups on each individual name unless it's a different last name, which is as expected but not what I need.
Can this be done in one SQL query?
SELECT Length(lastname)
FROM MyTable
GROUP BY Length(lastname)
select distinct(LENGTH(lastname)) from mynames;
Select count(*), Length(column_name) from table_name group by Length(column_name);
This will work for the different lengths in a single column.
I'm somewhat new to SQL queries, and I'm struggling with this particular problem.
Let's say I have query that returns the following 3 records (kept to one column for simplicity):
Tom
Jack
Tom
And I want to have those results grouped by the name and also include the fraction (ratio) of the occurrence of that name out of the total records returned.
So, the desired result would be (as two columns):
Tom | 2/3
Jack | 1/3
How would I go about it? Determining the numerator is pretty easy (I can just use COUNT() and GROUP BY name), but I'm having trouble translating that into a ratio out of the total rows returned.
SELECT name, COUNT(name)/(SELECT COUNT(1) FROM names) FROM names GROUP BY name;
Since the denominator is fixed, the "ratio" is directly proportional to the numerator. Unless you really need to show the denominator, it'll be a lot easier to just use something like:
select name, count(*) from your_table_name
group by name
order by count(*) desc
and you'll get the right data in the right order, but the number that's shown will be the count instead of the ratio.
If you really want that denominator, you'd do a count(*) on a non-grouped version of the same select -- but depending on how long the select takes, that could be pretty slow.
I am working on a pivot table query.
The schema is as follows
Sno, Name, District
The same name may appear in many districts eg take the sample data for example
1 Mike CA
2 Mike CA
3 Proctor JB
4 Luke MN
5 Luke MN
6 Mike CA
7 Mike LP
8 Proctor MN
9 Proctor JB
10 Proctor MN
11 Luke MN
As you see i have a set of 4 distinct districts (CA, JB, MN, LP). Now i wanted to get the pivot table generated for it by mapping the name against districts
Name CA JB MN LP
Mike 3 0 0 1
Proctor 0 2 2 0
Luke 0 0 3 0
i wrote the following query for this
select name,sum(if(District="CA",1,0)) as "CA",sum(if(District="JB",1,0)) as "JB",sum(if(District="MN",1,0)) as "MN",sum(if(District="LP",1,0)) as "LP" from district_details group by name
However there is a possibility that the districts may increase, in that case i will have to manually edit the query again and add the new district to it.
I want to know if there is a query which can dynamically take the names of distinct districts and run the above query. I know i can do it with a procedure and generating the script on the fly, is there any other method too?
I ask so because the output of the query "select distinct(districts) from district_details" will return me a single column having district name on each row, which i will like to be transposed to the column.
You simply cannot have a static SQL statement returning a variable number of columns. You need to build such statement each time the number of different districts changes. To do that, you execute first a
SELECT DISTINCT District FROM district_details;
This will give you the list of districts where there are details. You then build a SQL statement iterating over the previous result (pseudocode)
statement = "SELECT name "
For each row returned in d = SELECT DISTINCT District FROM district_details
statement = statement & ", SUM(IF(District=""" & d.District & """,1 ,0)) AS """ & d.District & """"
statement = statement & " FROM district_details GROUP BY name;"
And execute that query. You'll then need have to handle in your code the processing of the variable number of columns
a) "For each " is not supported in MySQL stored procedures.
b) Stored procedures cannot execute prepared statements from concatenated strings using so called dynamic SQL statements, nor can it return results with more than One distinct row.
c) Stored functions cannot execute dynamic SQL at all.
It is a nightmare to keep track of once you got a good idea and everyone seems to debunk it before they think "Why would anyone wanna..."
I hope you find your solution, I am still searching for mine.
The closes I got was
(excuse the pseudo code)
-> to stored procedure, build function that...
1) create temp table
2) load data to temp table from columns using your if statements
3) load the temp table out to INOUT or OUT parameters in a stored procedure as you would a table call... IF you can get it to return more than one row
Also another tip...
Store your districts as a table conventional style, load this and iterate by looping through the districts marked active to dynamically concatenate out a querystring that could be plain text for all the system cares
Then use;
prepare stmName from #yourqyerstring;
execute stmName;
deallocate prepare stmName;
(find much more on the stored procedures part of the mysql forum too)
to run a different set of districts every time, without having to re-design your original proc
Maybe it's easier in numerical form.
I work on plain text content in my tables and have nothing to sum, count or add up
The following assumes you want matches of distinct (name/district) pairs. I.e. Luke/CA and Duke/CA would yield two results:
SELECT name, District, count(District) AS count
FROM district_details
GROUP BY District, name
If this is not the case simply remove name from the GROUP BY clause.
Lastly, notice that I switched sum() for count() as you are trying to count all of the grouped rows rather than getting a summation of values.
Via comment by #cballou above, I was able to perform this sort of function which is not exactly what OP asked for but suited my similar situation, so adding it here to help those who come after.
Normal select statement:
SELECT d.id ID,
q.field field,
q.quota quota
FROM defaults d
JOIN quotas q ON d.id=q.default_id
Vertical results:
ID field quota
1 male 25
1 female 25
2 male 50
Select statement using group_concat:
SELECT d.id ID,
GROUP_CONCAT(q.fields SEPARATOR ",") fields,
GROUP_CONCAT(q.quotas SEPARATOR ",") quotas
FROM defaults d
JOIN quotas q ON d.id=q.default_id
Then I get comma-separated fields of "fields" and "quotas" which I can then easily process programmatically later.
Horizontal results:
ID fields quotas
1 male,female 25,25
2 male 50
Magic!