about QSqlQuery ,how can i get columns

[tsuibin]

QSqlQuery query;
query.exec("select * from table");



how to know
number of columns

i see the help

int QSqlQuery::size () const
Returns the size of the result (number of rows returned), or -1 if the size cannot be determined or if the database does not support reporting information about query sizes. Note that for non-SELECT statements (isSelect() returns false), size() will return -1. If the query is not active (isActive() returns false), -1 is returned.


but it return -1, i use sqlite database

is there other ways to do

[Lykurg]

QSqlQuery::record() and QSqlRecord::count():

query->record()->count();

query->record()->count();

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(Assuming record is valid!)

[waynew]

If you created the table, you already know the number of columns. What is it you are trying to do?

[sparticus_37]

to find the column id tto use QSqlQuery::value() then look here
QSqlQuery Reference
your looking for QSqlQuery::record()

now for finding the number of records return by you query you can do something like this

QSqlQuery q;
q.exec("SELECT Count(*) FROM tablename WHERE condition");
q.next();
int numRows = q.value(0).toInt();
//if you expect this query to return a massive number of records don use int for this purpose
 
//now run your original query

QSqlQuery q;
q.exec("SELECT Count(*) FROM tablename WHERE condition");
q.next();
int numRows = q.value(0).toInt();
//if you expect this query to return a massive number of records don use int for this purpose

//now run your original query

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hope this helps