Question about mysql-d Object
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
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.
Re: Question about mysql-d Object
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
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
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
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
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!!!