I'm creating an aggregate from a anstime column in a view table in Denodo and I'm using a Cast to convert it to float and it works only for those numbers with period (example 123.123) but does not work for the numbers without period (example 123). Here's my code which only works for those numbers with period:
SELECT row_date,
case
when sum(cast(anstime as float)) is null or sum(cast(anstime as float)) = 0
then 0
else sum(cast(anstime as float))
end as xans
FROM table where anstime like '%.%'
group by row_date
Can someone please help me how to handle those without period?
My guess is you've got values in anstime which are are not numeric, hence why not having the where anstime like '%.%' predicate causes a failure, as has been mentioned in other comments.
You could try adding in an intermediate view before this one which strips out any non numeric values (leaving the decimal point character of course) and this might then allow you to not have to use the where anstime like '%.%' filter.
Perhaps the REGEXP function which would possibly help there
Your where anstime like '%.%' clause is going to restrict possible responses to places where anstime has a period in it. Remove that if you want to allow all values.
I appreciate those who responded to my concern. In the end we had to reach out to our developers to fix the data type of the column from varchar to float rather than doing a workaround.
Related
I am trying to bulk insert multiple records simultaneously into a KDB+ database:
> trades:([]time:`datetime$();side:`symbol$();qty:`float$();price:`float$();exch:`symbol$();sym:`symbol$())
> t: .z.z / intentionally the same time
> `trades insert (t t;`buy `sell;10 10;10 10;`exch `exch;`sym `sym)
However It raises an error at the sym column
'sym
[0] `depths insert (t t;`buy `sell;10 10;10 10; `exch `exch;`sym `sym)
^
Have no Idea what I could be doing wrong here, but it seems to be value invariant i.e. it always raises an error on the last column irrespective of the value provided.
Could someone please advise me how I should go about inserting bulk records into kdb+ with an time index as depicted above.
Thanks
In your original insert statement, you had spaces between
`sym `sym
,
`exch `exch
and `buy `sell. The spaces between the symbols makes it an apply or index instead of a list which you desire.
Additionally, because you have specified your qty and price as
float
, you would have to specify the numbers as float when you are inserting to the
trades
table.
The following line should accomplish what you are intending to do:
`trades insert (2#t;`buy`sell;10 10f;10 10f;`exch`exch;`sym`sym)
Lastly, I would recommend changing the schema for the qtycolumn to int/long, as quantity generally does not require decimal points.
Hope this helps!
Daniel is on the money. To expand on his answer, q will collate space-separated lists into a single object for numeric values, and even then the type specification must be only present for the last item. Further details on list creation can be found here.
q)a:10f 10f
'10f
q)a:10 10f
Secondly, it's common for those learning kdb to often encounter type errors when appending to tables. The problem in this case is that kdb is not promoting a list of homogeneous atoms to a wider type (which is expected behaviour). The following is a useful little lambda for letting you know where you are going wrong when performing insert or upsert operations:
q)trades:([]time:`datetime$();side:`symbol$();qty:`float$();price:`float$();exch:`symbol$();sym:`symbol$())
q)rows:(t,t;`buy`sell;10 10;10 10;`exch`exch;`sym`sym)
q)insertTest:{[tab;rows] m:0!meta tab; wh: where not m[`t] ~' rt:.Q.ty each rows; #[flip;;enlist] `item`currType`expectedType!(m[`c] wh;rt wh; m[`t] wh)}
item currType expectedType
---------------------------
qty j f
price j f
I am currently using this formula to get all the data from everyone whose first name is "Peter", but my problem is that if someone is called "Simon Peter" this data is gonna show up on the formula output.
=QUERY('Data'!1:1000,"select * where B contains 'Peter'")
I know that for the other formulas if I add an * to the String this issue is resolved. But in this situation for the QUERY formula the same logic do not applies.
Do someone knows the correct syntax or a workaround?
How about classic SQL syntax
=QUERY('Data'!1:1000,"select * where B like 'Peter %'")
The LIKE keyword allows use of wildcard % to represent characters relative to the known parts of the searched string.
See the query reference: developers.google.com/chart/interactive/docs/querylanguage You could split firstname and lastname into separate columns, then only search for firstnames exactly equal to 'Peter'. Though you may want to also check if lowercase/uppercase where lower(B) contains 'peter' or whitespaces are present in unexpected places (e.g., trim()). You could also search only for values that start with Peter by using starts with instead of contains, or a regular expression using matches. – Brian D
It seems that for my case using 'starts with' is a perfect fit. Thank you!
I have a project model. Projects have a code attribute, which is in AAXXXX-YY format like "AA0001-18", "ZA0012-19", where AA is two characters, XXXX is a progressive number, and YY is the last two digits of the year of its creation.
I need to define a default scope that orders projects by code in a way that the year takes precedence over the other part. Supposing I have the codes "ZZ0001-17", "AA0001-18", and "ZZ002-17", "ZZ001-17" is first, "ZZ002-17" is second, and "AA001-18" is third.
I tried:
default_scope { order(:code) }
but I get "AA001-18" first.
Short answer
order("substring(code from '..$') ASC, code ASC")
Wait but why?
So as you said, you want to basically sort by 2 things:
the last 2 characters in the code string. YY
the rest of the code AAXXXX-
So first things first,
the order function as per Rails documentation will take the arguments you added and use them in the ORDER BY clause of the query.
Then, the substring function according to the documentation of PostgreSQL is:
substring(string from pattern)
If we want 2 characters .. from the end of the string $ we use ..$
Hence, substring(code from '..$')
For more information about pattern matching please refer to the documentation here.
Now finally, with the second part of our ordering the code which already will act as a sorter for all the preceding characters AAXXXX-.
I need to write a query that finds a number that can be less than, less than or equal, greater than, greater than or equal clause combined with a regex.
Is there a way to include the less than or greater than clause in the query, instead of rewriting the regex?
I need to get all the answers that contain a number less than or greater than a value depending on certain conditions.
So far I have this:
my_regex = "(^|;)([#{value}])($|;)"
Model.where("answer ~* ?", my_regex)
This will return the records that contain the value but not if I need greater than the value of the regex.
For example, if I need a value greater than 2:
if answer is "1;3;5;6;7;10" I would like to avoid rewriting the regexp to "(^|;)([#{value}-9]|1[0-9])($|;)" is that possible?
The format of your answer column is unfortunate but not hopeless. The ~* operator you're currently using tells me that this is PostgreSQL so you could unpack answer into an SQL array:
regexp_split_to_array(answer, ';')::int[]
and then use any to look for your desired value:
...where("? < any(regexp_split_to_array(answer, ';')::int[])", 2)
The ::int[] is a type cast to convert the array of strings that regexp_split_to_array gives you into the numbers that you want for the comparison. Then you check if any of the array elements are greater than two.
You could also change the format of the answer column to be an actual array of integers and say the much simpler:
...where('? < any(answer)', 2)
ActiveRecord knows how to work with PostgreSQL arrays too so model.answer would be a Ruby array over in Rails-land without any extra mucking about.
I have a table with 1 million+ records that contain names. I would like to be able to sort the list by the first letter in the name.
.. ABCDEFGHIJKLMNOPQRSTUVWXYZ
What is the most efficient way to setup the db table to allow for searching by the first character in the table.name field?
The best idea right now is to add an extra field which stores the first character of the name as an observer, index that field and then sort by that field. Problem is it's no longer necessarily alphabetical.
Any suggestions?
You said in a comment:
so lets ignore the first letter part. How can I all records that start with A? All A's no B...z ? Thanks – AnApprentice Feb 21 at 15:30
I issume you meant How can I RETURN all records...
This is the answer:
select * from t
where substr(name, 1, 1) = 'A'
I agree with the questions above as to why you would want to do this -- a regular index on the whole field is functionally equivalent. PostgreSQL (with some new ones in v. 9) has some rather powerful indexing capabilities for special cases which you might want to read about here http://www.postgresql.org/docs/9.1/interactive/sql-createindex.html