When I do the following:

auto mysql = new Mysql("localhost", 3306, "mt", "", "verwaltung");
auto rows = mysql.query("select field from my_table limit 50");

foreach(row;rows){
 writeln(row["field"]);}

// second time same loop

foreach(row;rows){
 writeln(row["field"]);}

I only get the output of the first loop (50 lines), probably this is a feature
not a bug, but what kind of Object is rows?

A nested loop, did not worked either:

foreach(row;rows){
 foreach(field;row){
 writeln(field);}
}

Which other ways to access the elements of rows do I have?

Sorry, but I am very new on D, (it may be the best language available, I don't know yet, but it is really the most interesting!) thank you!

On Monday, 7 December 2015 at 14:40:12 UTC, Martin Tschierschke wrote:
> When I do the following:
>
> auto mysql = new Mysql("localhost", 3306, "mt", "", "verwaltung");
> auto rows = mysql.query("select field from my_table limit 50");
>
> foreach(row;rows){
>  writeln(row["field"]);}
>
> // second time same loop
>
> foreach(row;rows){
>  writeln(row["field"]);}
>
> I only get the output of the first loop (50 lines), probably this is a feature
> not a bug, but what kind of Object is rows?
>
> A nested loop, did not worked either:
>
> foreach(row;rows){
>  foreach(field;row){
>  writeln(field);}
> }
>
> Which other ways to access the elements of rows do I have?
>
> Sorry, but I am very new on D, (it may be the best language available, I don't know yet, but it is really the most interesting!) thank you!

I suppose that's because the rows object is a mysql cursor, which means you can only iterate it once, and only forward (Not sure how it is implemented in mysql-d). It seems like your inner loop is exhausting it.

If you need random access or multiple iterations, you first need to copy your rows into another array/structure, and then you can do whatever you want with it.

On Monday, 7 December 2015 at 14:40:12 UTC, Martin Tschierschke wrote:
> When I do the following:
>
> auto mysql = new Mysql("localhost", 3306, "mt", "", "verwaltung");
> auto rows = mysql.query("select field from my_table limit 50");
>
> foreach(row;rows){
>  writeln(row["field"]);}
>
> // second time same loop
>
> foreach(row;rows){
>  writeln(row["field"]);}
>
> I only get the output of the first loop (50 lines), probably this is a feature
> not a bug, but what kind of Object is rows?
>
> A nested loop, did not worked either:
>
> foreach(row;rows){
>  foreach(field;row){
>  writeln(field);}
> }
>
> Which other ways to access the elements of rows do I have?
>
> Sorry, but I am very new on D, (it may be the best language available, I don't know yet, but it is really the most interesting!) thank you!

what if you make array from it:
import std.array: array;
auto rows = mysql.query("select field from my_table limit 50").array;

On Monday, 7 December 2015 at 16:11:19 UTC, Daniel Kozak wrote:
> On Monday, 7 December 2015 at 14:40:12 UTC, Martin Tschierschke wrote:
>> When I do the following:
>>
>> auto mysql = new Mysql("localhost", 3306, "mt", "", "verwaltung");
>> auto rows = mysql.query("select field from my_table limit 50");
>>
>> foreach(row;rows){
>>  writeln(row["field"]);}
>>
>> // second time same loop
>>
>> foreach(row;rows){
>>  writeln(row["field"]);}
>>
[...]
>> A nested loop, did not worked either:
>>
>> foreach(row;rows){
>>  foreach(field;row){
>>  writeln(field);}
>> }
>>
>> Which other ways to access the elements of rows do I have?
>>
[...]
> what if you make array from it:
> import std.array: array;
> auto rows = mysql.query("select field from my_table limit 50").array;
Thank you both for your answers!
This worked, for the first part of my question.
Now I took a work around, getting the field names in a separate mysql-request,
but they should be available in the row object, too?

V Tue, 08 Dec 2015 14:34:53 +0000
Martin Tschierschke via Digitalmars-d-learn
<digitalmars-d-learn@puremagic.com> napsáno:

> On Monday, 7 December 2015 at 16:11:19 UTC, Daniel Kozak wrote:
> > On Monday, 7 December 2015 at 14:40:12 UTC, Martin Tschierschke wrote:
> >> When I do the following:
> >>
> >> auto mysql = new Mysql("localhost", 3306, "mt", "",
> >> "verwaltung");
> >> auto rows = mysql.query("select field from my_table limit 50");
> >>
> >> foreach(row;rows){
> >>  writeln(row["field"]);}
> >>
> >> // second time same loop
> >>
> >> foreach(row;rows){
> >>  writeln(row["field"]);}
> >> 
> [...]
> >> A nested loop, did not worked either:
> >>
> >> foreach(row;rows){
> >>  foreach(field;row){
> >>  writeln(field);}
> >> }
> >>
> >> Which other ways to access the elements of rows do I have?
> >> 
> [...]
> > what if you make array from it:
> > import std.array: array;
> > auto rows = mysql.query("select field from my_table limit
> > 50").array;
> Thank you both for your answers!
> This worked, for the first part of my question.
> Now I took a work around, getting the field names in a separate
> mysql-request,
> but they should be available in the row object, too?
> 
rows.fields();

V Tue, 08 Dec 2015 14:34:53 +0000
Martin Tschierschke via Digitalmars-d-learn
<digitalmars-d-learn@puremagic.com> napsáno:

> On Monday, 7 December 2015 at 16:11:19 UTC, Daniel Kozak wrote:
> > On Monday, 7 December 2015 at 14:40:12 UTC, Martin Tschierschke wrote:
> >> When I do the following:
> >>
> >> auto mysql = new Mysql("localhost", 3306, "mt", "",
> >> "verwaltung");
> >> auto rows = mysql.query("select field from my_table limit 50");
> >>
> >> foreach(row;rows){
> >>  writeln(row["field"]);}
> >>
> >> // second time same loop
> >>
> >> foreach(row;rows){
> >>  writeln(row["field"]);}
> >> 
> [...]
> >> A nested loop, did not worked either:
> >>
> >> foreach(row;rows){
> >>  foreach(field;row){
> >>  writeln(field);}
> >> }
> >>
> >> Which other ways to access the elements of rows do I have?
> >> 
> [...]
> > what if you make array from it:
> > import std.array: array;
> > auto rows = mysql.query("select field from my_table limit
> > 50").array;
> Thank you both for your answers!
> This worked, for the first part of my question.
> Now I took a work around, getting the field names in a separate
> mysql-request,
> but they should be available in the row object, too?
> 

rows.fieldNames() this one is better result type is string[]

On Tuesday, 8 December 2015 at 15:14:06 UTC, Daniel Kozak wrote:
[...]
>> >> A nested loop, did not worked either:
>> >>
>> >> foreach(row;rows){
>> >>  foreach(field;row){
>> >>  writeln(field);}
>> >> }
[...]
>> Now I took a work around, getting the field names in a separate
>> mysql-request,
>> but they should be available in the row object, too?
>> 
>
> rows.fieldNames() this one is better result type is string[]
Thank you!!!