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Thread: QSqlQuery not working

  1. #1
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    Question QSqlQuery not working

    I'm stucked at this problem since a very long time ( about one day or more ), I just can't find what's wrong! it looks so simple and until now everything in the project did work fine, relational tables, and etc, well, I isolated it in a function, may I explain first, I've loaded a QComboBox with a QSqlQueryModel with this query: "SELECT name FROM Categories", ok. Then I need to insert the id of the selected item in another table (for using as relation), I made this function:

    Qt Code:
    1. int ProductsForm::categoryIdByName(const QString& name)
    2. {
    3. QSqlQuery categories = QSqlQuery(model->database());
    4. categories.prepare("SELECT id FROM Categories "
    5. "WHERE name=:name)");
    6. categories.bindValue(":name",name);
    7. categories.exec();
    8. if(categories.size()==-1)
    9. {
    10. qDebug() << "error";
    11. return 1;
    12. }
    13. return cate
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    I call it with QComboBox::currentText(), BUT, as you see my concern there, query size aways return -1, no item! i've tried a lot of other querys, like "SELECT * FROM Categories", but nothing! I'm SURE the database, tables and items where created and inserted respectively, the program did work fine until this, I hope you guys can enlight-me and help me kick off this meaningless error. thanks in advance, sorry my bad english.
    Last edited by BrainStorm; 15th August 2010 at 00:59. Reason: spelling corrections

  2. #2
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    Default Re: QSqlQuery not working

    Try to identify the problem using QSqlQuery::lastError().
    Last edited by saa7_go; 15th August 2010 at 01:10. Reason: updated contents

  3. #3
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    Default Re: QSqlQuery not working

    Quote Originally Posted by saa7_go View Post
    Try to identify the problem using QSqlQuery::lastError().
    it returns -1, no error =T

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    Default Re: QSqlQuery not working

    If you modify your codes to the following:
    Qt Code:
    1. int ProductsForm::categoryIdByName(const QString& name)
    2. {
    3. QSqlQuery categories(model->database());
    4. categories.exec(QString("SELECT id FROM Categories WHERE name='%1'").arg(name));
    5. if(categories.size()==-1)
    6. {
    7. qDebug() << "error";
    8. return 1;
    9. }
    10. .....
    11. }
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    is categories.size() value still -1 ?

  5. The following user says thank you to saa7_go for this useful post:

    BrainStorm (15th August 2010)

  6. #5
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    Default Re: QSqlQuery not working

    Quote Originally Posted by saa7_go View Post
    If you modify your codes to the following:
    Qt Code:
    1. int ProductsForm::categoryIdByName(const QString& name)
    2. {
    3. QSqlQuery categories(model->database());
    4. categories.exec(QString("SELECT id FROM Categories WHERE name='%1'").arg(name));
    5. if(categories.size()==-1)
    6. {
    7. qDebug() << "error";
    8. return 1;
    9. }
    10. .....
    11. }
    To copy to clipboard, switch view to plain text mode 

    is categories.size() value still -1 ?
    yesss...

  7. #6
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    Default Re: QSqlQuery not working

    Qt Code:
    1. int ProductsForm::categoryIdByName(const QString& name)
    2. {
    3. QSqlQuery categories = QSqlQuery(model->database());
    4. categories.exec(QString("SELECT id FROM Categories WHERE name='%1'").arg(name));
    5. categories.first();
    6. return categories.value(0).toInt();
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    it works now, and i still don't know why! ^^" but thanks anyway

  8. #7
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    Default Re: QSqlQuery not working

    Are you using sqlite database? If you are using sqlite, it doesn't support reporting information about query sizes. So, this is why you always get -1.

  9. #8
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    Default Re: QSqlQuery not working

    Quote Originally Posted by saa7_go View Post
    Are you using sqlite database? If you are using sqlite, it doesn't support reporting information about query sizes. So, this is why you always get -1.
    yes, i'm using sqlite

  10. #9
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    Default Re: QSqlQuery not working

    Quote Originally Posted by BrainStorm View Post
    yes, i'm using sqlite
    then you can check via
    Qt Code:
    1. QSqlQuery categories = QSqlQuery(model->database());
    2. categories.prepare("SELECT id FROM Categories "
    3. "WHERE name=:name)");
    4. categories.bindValue(":name",name);
    5. categories.exec();
    6. if (!categories.next())
    7. {
    8. // error and return;
    9. }
    10.  
    11. categories.value(0)/*...*/
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  11. #10
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    Default Re: QSqlQuery not working

    Is this code "copy and paste" ? If YES, You have an error in line 2. Signe ) after :name.

  12. #11
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    Default Re: QSqlQuery not working

    Quote Originally Posted by Lykurg View Post
    then you can check via
    Qt Code:
    1. QSqlQuery categories = QSqlQuery(model->database());
    2. categories.prepare("SELECT id FROM Categories "
    3. "WHERE name=:name)");
    4. categories.bindValue(":name",name);
    5. categories.exec();
    6. if (!categories.next())
    7. {
    8. // error and return;
    9. }
    10.  
    11. categories.value(0)/*...*/
    To copy to clipboard, switch view to plain text mode 
    i see.. but i think using QSqlQuery::next(); once is the same as using QSqlQuery::first();

  13. #12
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    Default Re: QSqlQuery not working

    By the way, does anyone knows how to create a button (flat would be nice) that drops a drop menu?
    Last edited by BrainStorm; 16th August 2010 at 00:43. Reason: spelling corrections

  14. #13
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    Default Re: QSqlQuery not working

    Quote Originally Posted by BrainStorm View Post
    i see.. but i think using QSqlQuery::next(); once is the same as using QSqlQuery::first();
    Yes, missed that, since in the code snippet the return was not checked if it is valid.

    Quote Originally Posted by BrainStorm View Post
    By the way, does anyone knows how to create a button (flat would be nice) that drops a drop menu?
    Use a normal buttun and set a menu via QPushButton::setMenu(). for flat use QPushButton::setFlat().

  15. The following user says thank you to Lykurg for this useful post:

    BrainStorm (16th August 2010)

  16. #14
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    Default Re: QSqlQuery not working

    Quote Originally Posted by Lykurg View Post
    Use a normal buttun and set a menu via QPushButton::setMenu(). for flat use QPushButton::setFlat().
    Ohh.. i see ^^ thanks, i was using QMenu::popup() with QPushButton::pos() :p

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