concatenation

问题 I have a table like this: title part desc Blah This 1 This begins the Blah This 2 example table. Some Record 1 Hello Another 1 This text extends a bit Another 2 further so it is in Another 3 another record in the Another 4 table In Access, I am looking to build a query/SQL to GROUP BY title and concatenate the desc field so it looks like this: title desc Blah This This begins the example table. Some Record Hello Another This text extends a bit further so it is in another record in the table

问题 i have two arrays given below Array ( [0] => 2013-07-09 [1] => 2013-07-16 [2] => 2013-07-23 [3] => 2013-07-30 ) Array ( [0] => 2013-07-16 [1] => 2013-07-23 [2] => 2013-07-30 [3] => 2013-08-06 ) i want to concatenate two array element values by special character.given output below: Array ( [0] => 2013-07-09 : 2013-07-16 [1] => 2013-07-16 : 2013-07-23 [2] => 2013-07-23 : 2013-08-30 [3] => 2013-08-30 : 2013-08-06 ) 回答1: Try with array_map like this $combined = array_map(function($a, $b) { return

问题 I want to save a changing set of ggplot is different files. To do this I use a for-loop looking something like this: save = c("plot1","plot2") for (i in 1:length(save)){ ggsave(cat(save[i],"\n"), file="i.pdf") } "plot1" and "plot2" are working ggplots (=names of the plot objects). Because I got the following error: Error in ggsave(cat(save[i], "\n"), file = "i.pdf") : plot should be a ggplot2 plot I tried the cat-function. It returns the same error with or without the function. If I enter the

问题 I am trying to concatenate a few fields into a single one, but only keep unique values in the resulting string. Example: title_orig | title_fr | title_de | title_it --------------------------------------------------------------------- KANDAHAR | KANDAHAR | REISE NACH KANDAHAR | VIAGGO A KANDAHAR SCREAM 2 | SCREAM 2 | SCREAM 2 | SCREAM 2 With CONCAT_WS(', ', title_orig, title_fr, title_de, title_it) AS titles I would get titles ------------------------------------------------------------

问题 I am trying to concatenate a few fields into a single one, but only keep unique values in the resulting string. Example: title_orig | title_fr | title_de | title_it --------------------------------------------------------------------- KANDAHAR | KANDAHAR | REISE NACH KANDAHAR | VIAGGO A KANDAHAR SCREAM 2 | SCREAM 2 | SCREAM 2 | SCREAM 2 With CONCAT_WS(', ', title_orig, title_fr, title_de, title_it) AS titles I would get titles ------------------------------------------------------------

问题 Is there any simple univesal way to add 2 arrays into one? In the case below it is not possible simply use C := A + B statement... I would like to avoid making algorhytm for it everytime . TPerson = record Birthday: Tdate; Name, Surname:string; end; Tpeople = array of TPerson; var A, B, C:Tpeople; C:=A+B; // it is not possible thanx 回答1: Due to the two string fields in each TPerson record, you can't just use binary "move", since you'll mess the reference counting of string - especially in a

问题 I have a Person model and I am using a django form to edit another object with a foreign key to Person . The person model has first_name and last_name fields. I want to run a method to filter results for the drop down box of the foreign reference. I am trying to use values_list() to override the form field options (choices property) like so: data.form.fields['person'].choices = GetPersons().values_list('id', 'first_name') GetPersons() just filters the Person class like return Person.objects

问题 $variable = 'for linebreak add 2 spaces at end'; Value of this variable everytime changes. How to add some text or html before and after this string? E.g. if we want to add '<div>' before and '</div>' after, string should look like: $variable = '<div>for linebreak add 2 spaces at end</div>'; 回答1: Marko's solution is the way to go for simple cases. If you need to concatenate many strings, it is said that joining arrays is much faster. $string[]='<div>'; $string[]= $variable; $string[]='</div>'

问题 tl:dr How can I concatenate const char* with std::string , neatly and elegantly, without multiple function calls. Ideally in one function call and have the output be a const char* . Is this impossible, what is an optimum solution? Initial Problem The biggest barrier I have experienced with C++ so far is how it handles strings. In my opinion, of all the widely used languages, it handles strings the most poorly. I've seen other questions similar to this that either have an answer saying "use

问题 tl:dr How can I concatenate const char* with std::string , neatly and elegantly, without multiple function calls. Ideally in one function call and have the output be a const char* . Is this impossible, what is an optimum solution? Initial Problem The biggest barrier I have experienced with C++ so far is how it handles strings. In my opinion, of all the widely used languages, it handles strings the most poorly. I've seen other questions similar to this that either have an answer saying "use