Count distinct case when postgresql

The query returns the unique combination of bcolor and fcolor from the ttable. Subject: Re: select count of distinct rows. I need to compare all fields. Well, in this case it does not. I use a CASE statement to perform a COUNT all the time.

Usually I do this to set a condition, usually time based. Wondering if I could have a bit of help. I have a dataset which has duplicated order numbers in it. Historically the expression ought to have been defined as count (). Further, certain use cases you may not be able to get by with close enough counts–you may have to be perfectly accurate.

Count distinct or HyperLogLog. For this case count distinct in a distributed fashion will still be faster than a single node for very large datasets. But, if you can get by with close counts HyperLogLog is your friend. So, couple of days ago, some guy, from Periscope company wrote a blogpost about getting number of distinct elements, per group, faster using subqueries.

The COALESCE function tells SAS to replace missing values with and then sum the returned values of both the conditions. SQL Server gives you the ability to store mixed case data in your databases, but depending on how you create your databases SQL Server will ignore the case when you issue T-SQL commands. One of the problems you may be faced with is that you want to get a distinct list of values from a table to show. The charts track duration of queries in milliseconds, so lower values are better. On the other han count (1) takes an argument.

Or a user could be active days in a row, but should only be counted once when the window covers any part of that date range. SAS SQL : Use Distinct in CASE WHEN. NOT NULL, ip_address inet, offence text, count. Stack Exchange Network Stack Exchange network consists of 1QA communities including Stack Overflow , the largest, most trusted online community for developers to learn, share their knowledge, and build their careers. First things first: If you have a huge dataset and can tolerate some imprecision, a probabilistic counter like HyperLogLog can be your best bet.

In postgres, distinct aggregates are a blind spot in the planner. But the distinct aggregates are not really seen by the planner, and they are always implemented with a sort. So this is a peculiar case for postgres. There may be a situation when you have multiple duplicate records in a table.

While fetching such records, it makes more sense to fetch only unique records instead of fetching duplicate records. The following says get the name and year from ceos for the set of rows where name is distinct. Determining different data in tables. USING (foo,bar,baz) is just a macro for: t1.

DISTINCT itself is handled well, e. The task because slightly more verbose and daunting when joining a table,. We can count during aggregation using GROUP BY to make distinct when needed after the select statement to show the data with counts. Remember that you must include the columns that are before the count in GROUP BY: SELECT lt;columngt;, COUNT (lt;columngt;).