Re: Question about mysql-d Object

[Martin Tschierschke via Digitalmars-d-learn]

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?

Re: Question about mysql-d Object

[Daniel Kozak via Digitalmars-d-learn]

V Tue, 08 Dec 2015 14:34:53 +
Martin Tschierschke via Digitalmars-d-learn
 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();

Re: Question about mysql-d Object

[Daniel Kozak via Digitalmars-d-learn]

V Tue, 08 Dec 2015 14:34:53 +
Martin Tschierschke via Digitalmars-d-learn
 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[]

Re: Question about mysql-d Object

[Martin Tschierschke via Digitalmars-d-learn]

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!!!

Question about mysql-d Object

[Martin Tschierschke via Digitalmars-d-learn]

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!

Re: Question about mysql-d Object

[Daniel Kozak via Digitalmars-d-learn]

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;

Re: Question about mysql-d Object

[Márcio Martins via Digitalmars-d-learn]

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.