I feel like to comment here on "because it can't use indexes for such things".  This is not a serious reply IMO. It is just another way or saying "Please shut up!"

How many existing string functions (http://dev.mysql.com/doc/refman/5.6/en/string-functions.html) use an index? Does "select concat('a','b');" do for instance? I cannot think of any. And why do we have 'stored programs' if a database server should only do things that uses indexes? Does a WHILE-loop inside a stroed program use an index? 

Unlike most other RDBMS, MySQL has a tradition to do things in the application thet other RDBMS would do in the database. But that traditions is/was because of lack of functionality in the server before 5.0 (what is still the case in some respects.  Try compare a MySQL TRIGGER with an Oracle or SQL Server same, for instance).

That said: this functionality can be implemented in a stored function using existing string functions (or in the application, as sugggested) quite easily. It is not possible (or desirable) to add build-in functions for everything.  And I have no clue is such string function exists in other RDBMS. 


-- Peter
-- Webyog


On Wed, Mar 19, 2014 at 4:03 PM, Reindl Harald <h.reindl@thelounge.net> wrote:


Am 19.03.2014 15:51, schrieb Roberto Spadim:
> hi guys, i'm not finding a function to return how many character i have, for example:
>
> "banana"
>
> i want a function that return 2 "n" characters, example:
> substr_count("banana","n") => 2
>
> sorry it a begginners question, but i didn't found it in mysql/mariadb manual

that is not the job of the database server because it
can't use indexes for such things - just iterate
the result and do it in the application


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