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Detect if SQLite UPDATE statement does not actually update anything

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sqlsqliteqsqlquery
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  • K Offline
    K Offline
    Kofr
    wrote on last edited by Kofr
    #1

    I use statement like this

    QString queryContent = "UPDATE \'" + parentName + "\' SET " + column + " = :value WHERE row = " + QString::number(t_row);
    
    

    Row is the Primary Index.
    When I execute query with for example t_row = 60 and such table contains 55 row, the UPDATE statement is executed successfully with no errors, but does not updait anything.
    How to make SQL query fail in such case, so I can detect the incorrect data?
    ps. UPDATE OR FAIL does not help in case with WHERE filtering.

    Paul ColbyP 1 Reply Last reply
    0
    • K Kofr

      I use statement like this

      QString queryContent = "UPDATE \'" + parentName + "\' SET " + column + " = :value WHERE row = " + QString::number(t_row);
      
      

      Row is the Primary Index.
      When I execute query with for example t_row = 60 and such table contains 55 row, the UPDATE statement is executed successfully with no errors, but does not updait anything.
      How to make SQL query fail in such case, so I can detect the incorrect data?
      ps. UPDATE OR FAIL does not help in case with WHERE filtering.

      Paul ColbyP Offline
      Paul ColbyP Offline
      Paul Colby
      wrote on last edited by
      #2

      Hi @Kofr,

      ... the UPDATE statement is executed successfully with no errors, but does not updait anything.
      How to make SQL query fail in such case, so I can detect the incorrect data?

      You can use QSqlQuery::numRowsAffected(), eg:

      if (query.numRowsAffected() < 1) {
          // no rows were updated - handle this however you like.
      }
      

      Cheers.

      K 1 Reply Last reply
      1
      • Paul ColbyP Paul Colby

        Hi @Kofr,

        ... the UPDATE statement is executed successfully with no errors, but does not updait anything.
        How to make SQL query fail in such case, so I can detect the incorrect data?

        You can use QSqlQuery::numRowsAffected(), eg:

        if (query.numRowsAffected() < 1) {
            // no rows were updated - handle this however you like.
        }
        

        Cheers.

        K Offline
        K Offline
        Kofr
        wrote on last edited by
        #3

        @Paul-Colby thx for the answer. QSqlQuery::numRowsAffected() does not work with SQLite

        1 Reply Last reply
        0
        • SGaistS Offline
          SGaistS Offline
          SGaist
          Lifetime Qt Champion
          wrote on last edited by
          #4

          Hi,

          Strange, this is implemented in the plugin. Which version of Qt are you using ?

          Interested in AI ? www.idiap.ch
          Please read the Qt Code of Conduct - https://forum.qt.io/topic/113070/qt-code-of-conduct

          K 1 Reply Last reply
          1
          • SGaistS SGaist

            Hi,

            Strange, this is implemented in the plugin. Which version of Qt are you using ?

            K Offline
            K Offline
            Kofr
            wrote on last edited by
            #5

            @SGaist I use Qt 5.7.0
            query.numRowsAffected() returns -1
            and driver.hasFeature(QSqlDriver::QuerySize) returns false

            1 Reply Last reply
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            • SGaistS Offline
              SGaistS Offline
              SGaist
              Lifetime Qt Champion
              wrote on last edited by
              #6

              QuerySize is not the same thing as numRowsAffected.

              QuerySize is for whether the driver is able to give the number of rows returned by a query.

              Interested in AI ? www.idiap.ch
              Please read the Qt Code of Conduct - https://forum.qt.io/topic/113070/qt-code-of-conduct

              K 1 Reply Last reply
              0
              • SGaistS SGaist

                QuerySize is not the same thing as numRowsAffected.

                QuerySize is for whether the driver is able to give the number of rows returned by a query.

                K Offline
                K Offline
                Kofr
                wrote on last edited by
                #7

                @SGaist there is no other argument in hasFeature(QSqlDriver::???) for checking for numRowsAffected()
                and query.numRowsAffected() returns -1 all the time even if UPDATE's succesful. So far in my case.

                1 Reply Last reply
                0
                • SGaistS Offline
                  SGaistS Offline
                  SGaist
                  Lifetime Qt Champion
                  wrote on last edited by
                  #8

                  Can you show how you setup and run your query ?

                  Interested in AI ? www.idiap.ch
                  Please read the Qt Code of Conduct - https://forum.qt.io/topic/113070/qt-code-of-conduct

                  1 Reply Last reply
                  1

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