MySQL: Count the distinct rows per day
SELECT DATE(timestamp) Date, COUNT(DISTINCT ipNum) totalCOunt FROM tableName GROUP BY DATE(timestamp) SQLFiddle Demo
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C++ – how to find the length of an integer
Not necessarily the most efficient, but one of the shortest and most readable using C++: std::to_string(num).length()
Select top distinct results ordered by frequency
I haven’t tested it, so the syntax might not be perfect, but what about something like this : select name, count(*) as frequency from your_table group by name order by count(*) desc Should give you unique names and the corresponding number of times each name appears in the table, ordered by that number.
SqlAlchemy: count of distinct over multiple columns
The exact query can be produced using the tuple_() construct: session.query( func.count(distinct(tuple_(Hit.ip_address, Hit.user_agent)))).scalar()
Elegant way of counting occurrences in a java collection
Now let’s try some Java 8 code: static public Map<String, Integer> toMap(List<String> lst) { return lst.stream() .collect(HashMap<String, Integer>::new, (map, str) -> { if (!map.containsKey(str)) { map.put(str, 1); } else { map.put(str, map.get(str) + 1); } }, HashMap<String, Integer>::putAll); } static public Map<String, Integer> toMap(List<String> lst) { return lst.stream().collect(Collectors.groupingBy(s -> s, Collectors.counting())); } I think this … Read more
How can I get SQL statement created by ActiveRecord#find without actually executing it?
For Rails 3: Check out the ActiveRecord::Relation docs at the Rails 3 docs. # get the relation rel = User.complex_scope.chained_complex_scope # get the SQL # this does not execute the query sql = rel.to_sql # find out how many records # this executes the query behind the scenes count = rel.size
Finding occurrences of a word in a string in python 3
If you’re going for efficiency: import re count = sum(1 for _ in re.finditer(r’\b%s\b’ % re.escape(word), input_string)) This doesn’t need to create any intermediate lists (unlike split()) and thus will work efficiently for large input_string values. It also has the benefit of working correctly with punctuation – it will properly return 1 as the count … Read more
SQL: Count() based on column value
You can use a CASE expression with your aggregate to get a total based on the outcomeId value: select companyId, sum(case when outcomeid = 36 then 1 else 0 end) SalesCount, sum(case when outcomeid <> 36 then 1 else 0 end) NonSalesCount from yourtable group by companyId; See SQL Fiddle with Demo
Counting Using Group By Linq
var noticesGrouped = notices.GroupBy(n => n.Name). Select(group => new { NoticeName = group.Key, Notices = group.ToList(), Count = group.Count() });
PowerShell: how to count number of rows in csv file?
Get-Content and Measure-Object are fine for small files, but both are super inefficient with memory. I had real problems with large files. When counting rows in a 1GB file using either method, Powershell gobbled up all available memory on the server (8GB), then started paging to disk. I left it over an hour, but it … Read more