Number of items in Redis set
The SCARD command returns the cardinality (i.e. number of items) of a Redis set. http://redis.io/commands/scard There is a similar command (ZCARD) for sorted sets.
count
SQL count(*) performance
Mikael Eriksson has a good explanation bellow why the first query is fast: SQL server optimize it into: if exists(select * from BookChapters). So it goes looking for the presence of one row instead of counting all the rows in the table. For the other two queries, SQL Server would use the following rule. To … Read more
Getting a count of rows in a datatable that meet certain criteria
One easy way to accomplish this is combining what was posted in the original post into a single statement: int numberOfRecords = dtFoo.Select(“IsActive=”Y””).Length; Another way to accomplish this is using Linq methods: int numberOfRecords = dtFoo.AsEnumerable().Where(x => x[“IsActive”].ToString() == “Y”).ToList().Count; Note this requires including System.Linq.
How to get the row count of a query in Android using SQLite?
Cursor.getCount()
Trying to get the average of a count resultset
You just can put your query as a subquery: SELECT avg(count) FROM ( SELECT COUNT (*) AS Count FROM Table T WHERE T.Update_time = (SELECT MAX (B.Update_time ) FROM Table B WHERE (B.Id = T.Id)) GROUP BY T.Grouping ) as counts Edit: I think this should be the same: SELECT count(*) / count(distinct T.Grouping) FROM … Read more
Getting the size of an array in an object
Javascript arrays have a length property. Use it like this: st.itemb.length
How to count each digit in a range of integers?
There’s a clear mathematical solution to a problem like this. Let’s assume the value is zero-padded to the maximum number of digits (it’s not, but we’ll compensate for that later), and reason through it: From 0-9, each digit occurs once From 0-99, each digit occurs 20 times (10x in position 1 and 10x in position … Read more
How to count differences between two files on linux?
If you want to count the number of lines that are different use this: diff -U 0 file1 file2 | grep ^@ | wc -l Doesn’t John’s answer double count the different lines?