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Forum Update on Monday, May 27th 2025

SQLite create table does not work when inserting variable into query

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  • I Offline
    I Offline
    iwoithe
    wrote on 18 Dec 2021, 00:22 last edited by
    #1

    I am attempting to insert a variable into a query using QSqlQuery::prepare(). The code is the following.

    QSqlQuery query;
    // value.at(2).toString() returns the ID of the profile as a QString
    QString profilePropTable = "profile_" + value.at(2).toString() + "_properties";
    query.prepare("create table if not exists ? (name TEXT, type TEXT, display_item TEXT");
    query.bindValue(0, profilePropTable);
    query.exec();
    

    The error I get (using query.lastError().text()) is "Parameter count mismatch". I have also used named placeholders with the same error.

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    0
    • C Offline
      C Offline
      ChrisW67
      wrote on 18 Dec 2021, 02:43 last edited by
      #2

      You cannot use a placeholder and bind variable in place of the table name, only for binding values to columns.

      Something like this:

      QString strQuery = QString(
        "create table if not exists profile_%1_properties name TEXT, type TEXT, display_item TEXT"
       ).arg(value.at(2).toString());
      query.exec(strQuery);
      

      but only if you are 100% certain the value in value.at(2) cannot be subverted by the user (security risk).

      I 1 Reply Last reply 18 Dec 2021, 03:49
      2
      • C ChrisW67
        18 Dec 2021, 02:43

        You cannot use a placeholder and bind variable in place of the table name, only for binding values to columns.

        Something like this:

        QString strQuery = QString(
          "create table if not exists profile_%1_properties name TEXT, type TEXT, display_item TEXT"
         ).arg(value.at(2).toString());
        query.exec(strQuery);
        

        but only if you are 100% certain the value in value.at(2) cannot be subverted by the user (security risk).

        I Offline
        I Offline
        iwoithe
        wrote on 18 Dec 2021, 03:49 last edited by
        #3

        @ChrisW67 It works. Thank you. :)

        but only if you are 100% certain the value in value.at(2) cannot be subverted by the user (security risk).

        The id (value.at(2)) is set in C++ and there is no way for the user to adjust this value.

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        18 Dec 2021, 00:22

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