[Gambas-bugtracker] Bug #2994: retrieve error gb.db2

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http://gambaswiki.org/bugtracker/edit?object=BUG.2994&from=L21haW4-

ROBERTO CARUSO reported a new bug.

Summary
-------

retrieve error gb.db2

Type             : Bug
Priority         : High
Gambas version   : 3.20
Product          : Unknown


Description
-----------

Hi to all,

This error appeared with gb.db2, with the previous version everything was ok.

sql query : SELECT COLUMN_NAME, DATA_TYPE, CHARACTER_MAXIMUM_LENGTH AS MAX_LENGTH, numeric_precision, numeric_scale FROM INFORMATION_SCHEMA.COLUMNS WHERE TABLE_SCHEMA = 'dbmaster' AND TABLE_NAME = 'list_commesse'

where res as Result, with res.count = 23

the instruction: 

MAX_LENGTH = res.All("MAX_LENGTH") ' or simply PRINT res.All("MAX_LENGTH")

where Dim MAX_LENGTH As New STRING[] ' also try with Variant[]

raise an error "Tipo non corrispondente: cercato Long, ottenuto NULL a suo posto"

The error is caused by NULL results of some rows in the MAX_LENGTH (AS) column ( view attachment)

But reading the data for each row everything is ok

For i = 0 To res.Max
    MAX_LENGTH.Add(res["MAX_LENGTH"]) 
    res.MoveNext
Next


System information
------------------

[System]
Gambas=3.20.0 6fff986 (master)
OperatingSystem=Linux
Distribution=Ubuntu 22.04.5 LTS (Jammy Jellyfish)
Kernel=6.8.0-52-generic
Architecture=x86_64
Cores=4
Memory=15976M
Language=it_IT.UTF-8
Platform=x11
Desktop=UBUNTU
DesktopResolution=96
DesktopScale=9
WidgetTheme=yaru
Font=Ubuntu,12
[Programs]
clang=Ubuntu clang version 14.0.0-1ubuntu1.1
dpkg=Debian "dpkg", programma di gestione dei pacchetti versione 1.21.1 (amd64).
gcc=gcc (Ubuntu 12.3.0-1ubuntu1~22.04) 12.3.0
git=git version 2.34.1
msgmerge=msgmerge (GNU gettext-tools) 0.21
rpmbuild=RPM version 4.17.0
[Libraries]
Cairo=libcairo.so.2.11600.0
Curl=libcurl.so.4.7.0
DBus=libdbus-1.so.3.19.13
GDK2=libgdk-x11-2.0.so.0.2400.33
GDK3=libgdk-3.so.0.2404.29
GStreamer=libgstreamer-1.0.so.0.2003.0
GTK+2=libgtk-x11-2.0.so.0.2400.33
GTK+3=libgtk-3.so.0.2404.29
OpenGL=libGL.so.1.7.0
Poppler=libpoppler.so.118.0.0
QT5=libQt5Core.so.5.15.3
QT6=libQt6Core.so.6.2.4
QT6=libQt6Core.so.6.5.3
RSvg=librsvg-2.so.2.48.0
SDL=libSDL2-2.0.so.0.18.2
SQLite3=libsqlite3.so.0.8.6
[Environment]
DBUS_SESSION_BUS_ADDRESS=unix:path=/run/user/1000/bus
DEFAULTS_PATH=/usr/share/gconf/ubuntu.default.path
DESKTOP_SESSION=ubuntu
DISPLAY=:1
GB_GUI=gb.gtk3
GDMSESSION=ubuntu
GIO_LAUNCHED_DESKTOP_FILE=/usr/share/applications/gambas3.desktop
GIO_LAUNCHED_DESKTOP_FILE_PID=6236
GJS_DEBUG_OUTPUT=stderr
GJS_DEBUG_TOPICS=JS ERROR;JS LOG
GNOME_DESKTOP_SESSION_ID=this-is-deprecated
GNOME_SHELL_SESSION_MODE=ubuntu
GPG_AGENT_INFO=/run/user/1000/gnupg/S.gpg-agent:0:1
GTK3_MODULES=xapp-gtk3-module
GTK_IM_MODULE=ibus
GTK_MODULES=gail:atk-bridge
HOME=<home>
INVOCATION_ID=269408d74448413f9ccab3a5298b197f
JOURNAL_STREAM=8:21122
LANG=it_IT.UTF-8
LANGUAGE=it_IT.UTF-8
LOGNAME=<user>
MANAGERPID=3941
MANDATORY_PATH=/usr/share/gconf/ubuntu.mandatory.path
PATH=<home>/.local/bin:/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin:/usr/games:/usr/local/games:/snap/bin:/snap/bin:<home>/.local/share/JetBrains/Toolbox/scripts
PWD=<home>
QT_ACCESSIBILITY=1
QT_IM_MODULE=ibus
QT_LOGGING_RULES=*.debug=false
QT_QPA_PLATFORMTHEME=qt5ct
SESSION_MANAGER=local/<hostname>:@/tmp/.ICE-unix/4205,unix/<hostname>:/tmp/.ICE-unix/4205
SHELL=/bin/bash
SHLVL=0
SSH_AGENT_LAUNCHER=openssh
SSH_AUTH_SOCK=/run/user/1000/openssh_agent
SYSTEMD_EXEC_PID=4226
TZ=:/etc/localtime
USER=<user>
USERNAME=<user>
WINDOWPATH=2
XAUTHORITY=/run/user/1000/gdm/Xauthority
XDG_CONFIG_DIRS=/etc/xdg/xdg-ubuntu:/etc/xdg
XDG_CURRENT_DESKTOP=ubuntu:GNOME
XDG_DATA_DIRS=/usr/share/ubuntu:/usr/share/gnome:/usr/local/share/:/usr/share/:/var/lib/snapd/desktop
XDG_MENU_PREFIX=gnome-
XDG_RUNTIME_DIR=/run/user/1000
XDG_SESSION_CLASS=user
XDG_SESSION_DESKTOP=ubuntu
XDG_SESSION_TYPE=x11
XMODIFIERS=@im=ibus


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